aboutsummaryrefslogtreecommitdiff
path: root/kernel
diff options
context:
space:
mode:
authorLinus Torvalds <torvalds@linux-foundation.org>2017-11-13 13:37:52 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2017-11-13 13:37:52 -0800
commit3e2014637c50e5d6a77cd63d5db6c209fe29d1b1 (patch)
treea672ed603262aeddda4490056b27b09791d0cbbb /kernel
parentf2be8bd52e7410c70145f73511a2e80f4797e1a5 (diff)
parent765cc3a4b224e22bf524fabe40284a524f37cdd0 (diff)
download96b-common-3e2014637c50e5d6a77cd63d5db6c209fe29d1b1.tar.gz
Merge branch 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull scheduler updates from Ingo Molnar: "The main updates in this cycle were: - Group balancing enhancements and cleanups (Brendan Jackman) - Move CPU isolation related functionality into its separate kernel/sched/isolation.c file, with related 'housekeeping_*()' namespace and nomenclature et al. (Frederic Weisbecker) - Improve the interactive/cpu-intense fairness calculation (Josef Bacik) - Improve the PELT code and related cleanups (Peter Zijlstra) - Improve the logic of pick_next_task_fair() (Uladzislau Rezki) - Improve the RT IPI based balancing logic (Steven Rostedt) - Various micro-optimizations: - better !CONFIG_SCHED_DEBUG optimizations (Patrick Bellasi) - better idle loop (Cheng Jian) - ... plus misc fixes, cleanups and updates" * 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (54 commits) sched/core: Optimize sched_feat() for !CONFIG_SCHED_DEBUG builds sched/sysctl: Fix attributes of some extern declarations sched/isolation: Document isolcpus= boot parameter flags, mark it deprecated sched/isolation: Add basic isolcpus flags sched/isolation: Move isolcpus= handling to the housekeeping code sched/isolation: Handle the nohz_full= parameter sched/isolation: Introduce housekeeping flags sched/isolation: Split out new CONFIG_CPU_ISOLATION=y config from CONFIG_NO_HZ_FULL sched/isolation: Rename is_housekeeping_cpu() to housekeeping_cpu() sched/isolation: Use its own static key sched/isolation: Make the housekeeping cpumask private sched/isolation: Provide a dynamic off-case to housekeeping_any_cpu() sched/isolation, watchdog: Use housekeeping_cpumask() instead of ad-hoc version sched/isolation: Move housekeeping related code to its own file sched/idle: Micro-optimize the idle loop sched/isolcpus: Fix "isolcpus=" boot parameter handling when !CONFIG_CPUMASK_OFFSTACK x86/tsc: Append the 'tsc=' description for the 'tsc=unstable' boot parameter sched/rt: Simplify the IPI based RT balancing logic block/ioprio: Use a helper to check for RT prio sched/rt: Add a helper to test for a RT task ...
Diffstat (limited to 'kernel')
-rw-r--r--kernel/cgroup/cpuset.c15
-rw-r--r--kernel/rcu/tree_plugin.h3
-rw-r--r--kernel/rcu/update.c3
-rw-r--r--kernel/sched/Makefile1
-rw-r--r--kernel/sched/core.c56
-rw-r--r--kernel/sched/deadline.c21
-rw-r--r--kernel/sched/debug.c18
-rw-r--r--kernel/sched/fair.c1049
-rw-r--r--kernel/sched/idle.c4
-rw-r--r--kernel/sched/isolation.c155
-rw-r--r--kernel/sched/rt.c316
-rw-r--r--kernel/sched/sched.h73
-rw-r--r--kernel/sched/topology.c49
-rw-r--r--kernel/time/tick-sched.c33
-rw-r--r--kernel/trace/trace_output.c12
-rw-r--r--kernel/trace/trace_sched_wakeup.c8
-rw-r--r--kernel/watchdog.c13
17 files changed, 1123 insertions, 706 deletions
diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c
index 4657e2924ecb..f7efa7b4d825 100644
--- a/kernel/cgroup/cpuset.c
+++ b/kernel/cgroup/cpuset.c
@@ -57,7 +57,7 @@
#include <linux/backing-dev.h>
#include <linux/sort.h>
#include <linux/oom.h>
-
+#include <linux/sched/isolation.h>
#include <linux/uaccess.h>
#include <linux/atomic.h>
#include <linux/mutex.h>
@@ -656,7 +656,6 @@ static int generate_sched_domains(cpumask_var_t **domains,
int csn; /* how many cpuset ptrs in csa so far */
int i, j, k; /* indices for partition finding loops */
cpumask_var_t *doms; /* resulting partition; i.e. sched domains */
- cpumask_var_t non_isolated_cpus; /* load balanced CPUs */
struct sched_domain_attr *dattr; /* attributes for custom domains */
int ndoms = 0; /* number of sched domains in result */
int nslot; /* next empty doms[] struct cpumask slot */
@@ -666,10 +665,6 @@ static int generate_sched_domains(cpumask_var_t **domains,
dattr = NULL;
csa = NULL;
- if (!alloc_cpumask_var(&non_isolated_cpus, GFP_KERNEL))
- goto done;
- cpumask_andnot(non_isolated_cpus, cpu_possible_mask, cpu_isolated_map);
-
/* Special case for the 99% of systems with one, full, sched domain */
if (is_sched_load_balance(&top_cpuset)) {
ndoms = 1;
@@ -683,7 +678,7 @@ static int generate_sched_domains(cpumask_var_t **domains,
update_domain_attr_tree(dattr, &top_cpuset);
}
cpumask_and(doms[0], top_cpuset.effective_cpus,
- non_isolated_cpus);
+ housekeeping_cpumask(HK_FLAG_DOMAIN));
goto done;
}
@@ -707,7 +702,8 @@ static int generate_sched_domains(cpumask_var_t **domains,
*/
if (!cpumask_empty(cp->cpus_allowed) &&
!(is_sched_load_balance(cp) &&
- cpumask_intersects(cp->cpus_allowed, non_isolated_cpus)))
+ cpumask_intersects(cp->cpus_allowed,
+ housekeeping_cpumask(HK_FLAG_DOMAIN))))
continue;
if (is_sched_load_balance(cp))
@@ -789,7 +785,7 @@ restart:
if (apn == b->pn) {
cpumask_or(dp, dp, b->effective_cpus);
- cpumask_and(dp, dp, non_isolated_cpus);
+ cpumask_and(dp, dp, housekeeping_cpumask(HK_FLAG_DOMAIN));
if (dattr)
update_domain_attr_tree(dattr + nslot, b);
@@ -802,7 +798,6 @@ restart:
BUG_ON(nslot != ndoms);
done:
- free_cpumask_var(non_isolated_cpus);
kfree(csa);
/*
diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h
index dd4d0d390e5b..910405dc6e5c 100644
--- a/kernel/rcu/tree_plugin.h
+++ b/kernel/rcu/tree_plugin.h
@@ -29,6 +29,7 @@
#include <linux/oom.h>
#include <linux/sched/debug.h>
#include <linux/smpboot.h>
+#include <linux/sched/isolation.h>
#include <uapi/linux/sched/types.h>
#include "../time/tick-internal.h"
@@ -2587,7 +2588,7 @@ static void rcu_bind_gp_kthread(void)
if (!tick_nohz_full_enabled())
return;
- housekeeping_affine(current);
+ housekeeping_affine(current, HK_FLAG_RCU);
}
/* Record the current task on dyntick-idle entry. */
diff --git a/kernel/rcu/update.c b/kernel/rcu/update.c
index 27694561f769..fbd56d6e575b 100644
--- a/kernel/rcu/update.c
+++ b/kernel/rcu/update.c
@@ -51,6 +51,7 @@
#include <linux/kthread.h>
#include <linux/tick.h>
#include <linux/rcupdate_wait.h>
+#include <linux/sched/isolation.h>
#define CREATE_TRACE_POINTS
@@ -714,7 +715,7 @@ static int __noreturn rcu_tasks_kthread(void *arg)
LIST_HEAD(rcu_tasks_holdouts);
/* Run on housekeeping CPUs by default. Sysadm can move if desired. */
- housekeeping_affine(current);
+ housekeeping_affine(current, HK_FLAG_RCU);
/*
* Each pass through the following loop makes one check for
diff --git a/kernel/sched/Makefile b/kernel/sched/Makefile
index a9ee16bbc693..e2f9d4feff40 100644
--- a/kernel/sched/Makefile
+++ b/kernel/sched/Makefile
@@ -27,3 +27,4 @@ obj-$(CONFIG_CGROUP_CPUACCT) += cpuacct.o
obj-$(CONFIG_CPU_FREQ) += cpufreq.o
obj-$(CONFIG_CPU_FREQ_GOV_SCHEDUTIL) += cpufreq_schedutil.o
obj-$(CONFIG_MEMBARRIER) += membarrier.o
+obj-$(CONFIG_CPU_ISOLATION) += isolation.o
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 9446b2e5eac5..5b82a0073532 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -26,6 +26,7 @@
#include <linux/profile.h>
#include <linux/security.h>
#include <linux/syscalls.h>
+#include <linux/sched/isolation.h>
#include <asm/switch_to.h>
#include <asm/tlb.h>
@@ -42,18 +43,21 @@
DEFINE_PER_CPU_SHARED_ALIGNED(struct rq, runqueues);
+#if defined(CONFIG_SCHED_DEBUG) && defined(HAVE_JUMP_LABEL)
/*
* Debugging: various feature bits
+ *
+ * If SCHED_DEBUG is disabled, each compilation unit has its own copy of
+ * sysctl_sched_features, defined in sched.h, to allow constants propagation
+ * at compile time and compiler optimization based on features default.
*/
-
#define SCHED_FEAT(name, enabled) \
(1UL << __SCHED_FEAT_##name) * enabled |
-
const_debug unsigned int sysctl_sched_features =
#include "features.h"
0;
-
#undef SCHED_FEAT
+#endif
/*
* Number of tasks to iterate in a single balance run.
@@ -83,9 +87,6 @@ __read_mostly int scheduler_running;
*/
int sysctl_sched_rt_runtime = 950000;
-/* CPUs with isolated domains */
-cpumask_var_t cpu_isolated_map;
-
/*
* __task_rq_lock - lock the rq @p resides on.
*/
@@ -525,7 +526,7 @@ int get_nohz_timer_target(void)
int i, cpu = smp_processor_id();
struct sched_domain *sd;
- if (!idle_cpu(cpu) && is_housekeeping_cpu(cpu))
+ if (!idle_cpu(cpu) && housekeeping_cpu(cpu, HK_FLAG_TIMER))
return cpu;
rcu_read_lock();
@@ -534,15 +535,15 @@ int get_nohz_timer_target(void)
if (cpu == i)
continue;
- if (!idle_cpu(i) && is_housekeeping_cpu(i)) {
+ if (!idle_cpu(i) && housekeeping_cpu(i, HK_FLAG_TIMER)) {
cpu = i;
goto unlock;
}
}
}
- if (!is_housekeeping_cpu(cpu))
- cpu = housekeeping_any_cpu();
+ if (!housekeeping_cpu(cpu, HK_FLAG_TIMER))
+ cpu = housekeeping_any_cpu(HK_FLAG_TIMER);
unlock:
rcu_read_unlock();
return cpu;
@@ -732,7 +733,7 @@ int tg_nop(struct task_group *tg, void *data)
}
#endif
-static void set_load_weight(struct task_struct *p)
+static void set_load_weight(struct task_struct *p, bool update_load)
{
int prio = p->static_prio - MAX_RT_PRIO;
struct load_weight *load = &p->se.load;
@@ -746,8 +747,16 @@ static void set_load_weight(struct task_struct *p)
return;
}
- load->weight = scale_load(sched_prio_to_weight[prio]);
- load->inv_weight = sched_prio_to_wmult[prio];
+ /*
+ * SCHED_OTHER tasks have to update their load when changing their
+ * weight
+ */
+ if (update_load && p->sched_class == &fair_sched_class) {
+ reweight_task(p, prio);
+ } else {
+ load->weight = scale_load(sched_prio_to_weight[prio]);
+ load->inv_weight = sched_prio_to_wmult[prio];
+ }
}
static inline void enqueue_task(struct rq *rq, struct task_struct *p, int flags)
@@ -2357,7 +2366,7 @@ int sched_fork(unsigned long clone_flags, struct task_struct *p)
p->static_prio = NICE_TO_PRIO(0);
p->prio = p->normal_prio = __normal_prio(p);
- set_load_weight(p);
+ set_load_weight(p, false);
/*
* We don't need the reset flag anymore after the fork. It has
@@ -3804,7 +3813,7 @@ void set_user_nice(struct task_struct *p, long nice)
put_prev_task(rq, p);
p->static_prio = NICE_TO_PRIO(nice);
- set_load_weight(p);
+ set_load_weight(p, true);
old_prio = p->prio;
p->prio = effective_prio(p);
delta = p->prio - old_prio;
@@ -3961,7 +3970,7 @@ static void __setscheduler_params(struct task_struct *p,
*/
p->rt_priority = attr->sched_priority;
p->normal_prio = normal_prio(p);
- set_load_weight(p);
+ set_load_weight(p, true);
}
/* Actually do priority change: must hold pi & rq lock. */
@@ -5727,10 +5736,6 @@ static inline void sched_init_smt(void) { }
void __init sched_init_smp(void)
{
- cpumask_var_t non_isolated_cpus;
-
- alloc_cpumask_var(&non_isolated_cpus, GFP_KERNEL);
-
sched_init_numa();
/*
@@ -5740,16 +5745,12 @@ void __init sched_init_smp(void)
*/
mutex_lock(&sched_domains_mutex);
sched_init_domains(cpu_active_mask);
- cpumask_andnot(non_isolated_cpus, cpu_possible_mask, cpu_isolated_map);
- if (cpumask_empty(non_isolated_cpus))
- cpumask_set_cpu(smp_processor_id(), non_isolated_cpus);
mutex_unlock(&sched_domains_mutex);
/* Move init over to a non-isolated CPU */
- if (set_cpus_allowed_ptr(current, non_isolated_cpus) < 0)
+ if (set_cpus_allowed_ptr(current, housekeeping_cpumask(HK_FLAG_DOMAIN)) < 0)
BUG();
sched_init_granularity();
- free_cpumask_var(non_isolated_cpus);
init_sched_rt_class();
init_sched_dl_class();
@@ -5934,7 +5935,7 @@ void __init sched_init(void)
atomic_set(&rq->nr_iowait, 0);
}
- set_load_weight(&init_task);
+ set_load_weight(&init_task, false);
/*
* The boot idle thread does lazy MMU switching as well:
@@ -5953,9 +5954,6 @@ void __init sched_init(void)
calc_load_update = jiffies + LOAD_FREQ;
#ifdef CONFIG_SMP
- /* May be allocated at isolcpus cmdline parse time */
- if (cpu_isolated_map == NULL)
- zalloc_cpumask_var(&cpu_isolated_map, GFP_NOWAIT);
idle_thread_set_boot_cpu();
set_cpu_rq_start_time(smp_processor_id());
#endif
diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c
index 4ae5c1ea90e2..f349f7e98dec 100644
--- a/kernel/sched/deadline.c
+++ b/kernel/sched/deadline.c
@@ -243,7 +243,7 @@ static void task_non_contending(struct task_struct *p)
if (p->state == TASK_DEAD)
sub_rq_bw(p->dl.dl_bw, &rq->dl);
raw_spin_lock(&dl_b->lock);
- __dl_clear(dl_b, p->dl.dl_bw, dl_bw_cpus(task_cpu(p)));
+ __dl_sub(dl_b, p->dl.dl_bw, dl_bw_cpus(task_cpu(p)));
__dl_clear_params(p);
raw_spin_unlock(&dl_b->lock);
}
@@ -1210,7 +1210,7 @@ static enum hrtimer_restart inactive_task_timer(struct hrtimer *timer)
}
raw_spin_lock(&dl_b->lock);
- __dl_clear(dl_b, p->dl.dl_bw, dl_bw_cpus(task_cpu(p)));
+ __dl_sub(dl_b, p->dl.dl_bw, dl_bw_cpus(task_cpu(p)));
raw_spin_unlock(&dl_b->lock);
__dl_clear_params(p);
@@ -1365,6 +1365,10 @@ enqueue_dl_entity(struct sched_dl_entity *dl_se,
update_dl_entity(dl_se, pi_se);
} else if (flags & ENQUEUE_REPLENISH) {
replenish_dl_entity(dl_se, pi_se);
+ } else if ((flags & ENQUEUE_RESTORE) &&
+ dl_time_before(dl_se->deadline,
+ rq_clock(rq_of_dl_rq(dl_rq_of_se(dl_se))))) {
+ setup_new_dl_entity(dl_se);
}
__enqueue_dl_entity(dl_se);
@@ -2167,7 +2171,7 @@ static void set_cpus_allowed_dl(struct task_struct *p,
* until we complete the update.
*/
raw_spin_lock(&src_dl_b->lock);
- __dl_clear(src_dl_b, p->dl.dl_bw, dl_bw_cpus(task_cpu(p)));
+ __dl_sub(src_dl_b, p->dl.dl_bw, dl_bw_cpus(task_cpu(p)));
raw_spin_unlock(&src_dl_b->lock);
}
@@ -2256,13 +2260,6 @@ static void switched_to_dl(struct rq *rq, struct task_struct *p)
return;
}
- /*
- * If p is boosted we already updated its params in
- * rt_mutex_setprio()->enqueue_task(..., ENQUEUE_REPLENISH),
- * p's deadline being now already after rq_clock(rq).
- */
- if (dl_time_before(p->dl.deadline, rq_clock(rq)))
- setup_new_dl_entity(&p->dl);
if (rq->curr != p) {
#ifdef CONFIG_SMP
@@ -2452,7 +2449,7 @@ int sched_dl_overflow(struct task_struct *p, int policy,
if (dl_policy(policy) && !task_has_dl_policy(p) &&
!__dl_overflow(dl_b, cpus, 0, new_bw)) {
if (hrtimer_active(&p->dl.inactive_timer))
- __dl_clear(dl_b, p->dl.dl_bw, cpus);
+ __dl_sub(dl_b, p->dl.dl_bw, cpus);
__dl_add(dl_b, new_bw, cpus);
err = 0;
} else if (dl_policy(policy) && task_has_dl_policy(p) &&
@@ -2464,7 +2461,7 @@ int sched_dl_overflow(struct task_struct *p, int policy,
* But this would require to set the task's "inactive
* timer" when the task is not inactive.
*/
- __dl_clear(dl_b, p->dl.dl_bw, cpus);
+ __dl_sub(dl_b, p->dl.dl_bw, cpus);
__dl_add(dl_b, new_bw, cpus);
dl_change_utilization(p, new_bw);
err = 0;
diff --git a/kernel/sched/debug.c b/kernel/sched/debug.c
index 2f93e4a2d9f6..1ca0130ed4f9 100644
--- a/kernel/sched/debug.c
+++ b/kernel/sched/debug.c
@@ -441,9 +441,11 @@ static void print_cfs_group_stats(struct seq_file *m, int cpu, struct task_group
P_SCHEDSTAT(se->statistics.wait_count);
}
P(se->load.weight);
+ P(se->runnable_weight);
#ifdef CONFIG_SMP
P(se->avg.load_avg);
P(se->avg.util_avg);
+ P(se->avg.runnable_load_avg);
#endif
#undef PN_SCHEDSTAT
@@ -558,16 +560,19 @@ void print_cfs_rq(struct seq_file *m, int cpu, struct cfs_rq *cfs_rq)
SEQ_printf(m, " .%-30s: %d\n", "nr_running", cfs_rq->nr_running);
SEQ_printf(m, " .%-30s: %ld\n", "load", cfs_rq->load.weight);
#ifdef CONFIG_SMP
+ SEQ_printf(m, " .%-30s: %ld\n", "runnable_weight", cfs_rq->runnable_weight);
SEQ_printf(m, " .%-30s: %lu\n", "load_avg",
cfs_rq->avg.load_avg);
SEQ_printf(m, " .%-30s: %lu\n", "runnable_load_avg",
- cfs_rq->runnable_load_avg);
+ cfs_rq->avg.runnable_load_avg);
SEQ_printf(m, " .%-30s: %lu\n", "util_avg",
cfs_rq->avg.util_avg);
- SEQ_printf(m, " .%-30s: %ld\n", "removed_load_avg",
- atomic_long_read(&cfs_rq->removed_load_avg));
- SEQ_printf(m, " .%-30s: %ld\n", "removed_util_avg",
- atomic_long_read(&cfs_rq->removed_util_avg));
+ SEQ_printf(m, " .%-30s: %ld\n", "removed.load_avg",
+ cfs_rq->removed.load_avg);
+ SEQ_printf(m, " .%-30s: %ld\n", "removed.util_avg",
+ cfs_rq->removed.util_avg);
+ SEQ_printf(m, " .%-30s: %ld\n", "removed.runnable_sum",
+ cfs_rq->removed.runnable_sum);
#ifdef CONFIG_FAIR_GROUP_SCHED
SEQ_printf(m, " .%-30s: %lu\n", "tg_load_avg_contrib",
cfs_rq->tg_load_avg_contrib);
@@ -1004,10 +1009,13 @@ void proc_sched_show_task(struct task_struct *p, struct pid_namespace *ns,
"nr_involuntary_switches", (long long)p->nivcsw);
P(se.load.weight);
+ P(se.runnable_weight);
#ifdef CONFIG_SMP
P(se.avg.load_sum);
+ P(se.avg.runnable_load_sum);
P(se.avg.util_sum);
P(se.avg.load_avg);
+ P(se.avg.runnable_load_avg);
P(se.avg.util_avg);
P(se.avg.last_update_time);
#endif
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 5c09ddf8c832..0989676c50e9 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -33,6 +33,7 @@
#include <linux/mempolicy.h>
#include <linux/migrate.h>
#include <linux/task_work.h>
+#include <linux/sched/isolation.h>
#include <trace/events/sched.h>
@@ -717,13 +718,8 @@ void init_entity_runnable_average(struct sched_entity *se)
{
struct sched_avg *sa = &se->avg;
- sa->last_update_time = 0;
- /*
- * sched_avg's period_contrib should be strictly less then 1024, so
- * we give it 1023 to make sure it is almost a period (1024us), and
- * will definitely be update (after enqueue).
- */
- sa->period_contrib = 1023;
+ memset(sa, 0, sizeof(*sa));
+
/*
* Tasks are intialized with full load to be seen as heavy tasks until
* they get a chance to stabilize to their real load level.
@@ -731,13 +727,10 @@ void init_entity_runnable_average(struct sched_entity *se)
* nothing has been attached to the task group yet.
*/
if (entity_is_task(se))
- sa->load_avg = scale_load_down(se->load.weight);
- sa->load_sum = sa->load_avg * LOAD_AVG_MAX;
- /*
- * At this point, util_avg won't be used in select_task_rq_fair anyway
- */
- sa->util_avg = 0;
- sa->util_sum = 0;
+ sa->runnable_load_avg = sa->load_avg = scale_load_down(se->load.weight);
+
+ se->runnable_weight = se->load.weight;
+
/* when this task enqueue'ed, it will contribute to its cfs_rq's load_avg */
}
@@ -785,7 +778,6 @@ void post_init_entity_util_avg(struct sched_entity *se)
} else {
sa->util_avg = cap;
}
- sa->util_sum = sa->util_avg * LOAD_AVG_MAX;
}
if (entity_is_task(se)) {
@@ -2026,7 +2018,7 @@ static u64 numa_get_avg_runtime(struct task_struct *p, u64 *period)
delta = runtime - p->last_sum_exec_runtime;
*period = now - p->last_task_numa_placement;
} else {
- delta = p->se.avg.load_sum / p->se.load.weight;
+ delta = p->se.avg.load_sum;
*period = LOAD_AVG_MAX;
}
@@ -2693,18 +2685,226 @@ account_entity_dequeue(struct cfs_rq *cfs_rq, struct sched_entity *se)
cfs_rq->nr_running--;
}
+/*
+ * Signed add and clamp on underflow.
+ *
+ * Explicitly do a load-store to ensure the intermediate value never hits
+ * memory. This allows lockless observations without ever seeing the negative
+ * values.
+ */
+#define add_positive(_ptr, _val) do { \
+ typeof(_ptr) ptr = (_ptr); \
+ typeof(_val) val = (_val); \
+ typeof(*ptr) res, var = READ_ONCE(*ptr); \
+ \
+ res = var + val; \
+ \
+ if (val < 0 && res > var) \
+ res = 0; \
+ \
+ WRITE_ONCE(*ptr, res); \
+} while (0)
+
+/*
+ * Unsigned subtract and clamp on underflow.
+ *
+ * Explicitly do a load-store to ensure the intermediate value never hits
+ * memory. This allows lockless observations without ever seeing the negative
+ * values.
+ */
+#define sub_positive(_ptr, _val) do { \
+ typeof(_ptr) ptr = (_ptr); \
+ typeof(*ptr) val = (_val); \
+ typeof(*ptr) res, var = READ_ONCE(*ptr); \
+ res = var - val; \
+ if (res > var) \
+ res = 0; \
+ WRITE_ONCE(*ptr, res); \
+} while (0)
+
+#ifdef CONFIG_SMP
+/*
+ * XXX we want to get rid of these helpers and use the full load resolution.
+ */
+static inline long se_weight(struct sched_entity *se)
+{
+ return scale_load_down(se->load.weight);
+}
+
+static inline long se_runnable(struct sched_entity *se)
+{
+ return scale_load_down(se->runnable_weight);
+}
+
+static inline void
+enqueue_runnable_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se)
+{
+ cfs_rq->runnable_weight += se->runnable_weight;
+
+ cfs_rq->avg.runnable_load_avg += se->avg.runnable_load_avg;
+ cfs_rq->avg.runnable_load_sum += se_runnable(se) * se->avg.runnable_load_sum;
+}
+
+static inline void
+dequeue_runnable_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se)
+{
+ cfs_rq->runnable_weight -= se->runnable_weight;
+
+ sub_positive(&cfs_rq->avg.runnable_load_avg, se->avg.runnable_load_avg);
+ sub_positive(&cfs_rq->avg.runnable_load_sum,
+ se_runnable(se) * se->avg.runnable_load_sum);
+}
+
+static inline void
+enqueue_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se)
+{
+ cfs_rq->avg.load_avg += se->avg.load_avg;
+ cfs_rq->avg.load_sum += se_weight(se) * se->avg.load_sum;
+}
+
+static inline void
+dequeue_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se)
+{
+ sub_positive(&cfs_rq->avg.load_avg, se->avg.load_avg);
+ sub_positive(&cfs_rq->avg.load_sum, se_weight(se) * se->avg.load_sum);
+}
+#else
+static inline void
+enqueue_runnable_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se) { }
+static inline void
+dequeue_runnable_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se) { }
+static inline void
+enqueue_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se) { }
+static inline void
+dequeue_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se) { }
+#endif
+
+static void reweight_entity(struct cfs_rq *cfs_rq, struct sched_entity *se,
+ unsigned long weight, unsigned long runnable)
+{
+ if (se->on_rq) {
+ /* commit outstanding execution time */
+ if (cfs_rq->curr == se)
+ update_curr(cfs_rq);
+ account_entity_dequeue(cfs_rq, se);
+ dequeue_runnable_load_avg(cfs_rq, se);
+ }
+ dequeue_load_avg(cfs_rq, se);
+
+ se->runnable_weight = runnable;
+ update_load_set(&se->load, weight);
+
+#ifdef CONFIG_SMP
+ do {
+ u32 divider = LOAD_AVG_MAX - 1024 + se->avg.period_contrib;
+
+ se->avg.load_avg = div_u64(se_weight(se) * se->avg.load_sum, divider);
+ se->avg.runnable_load_avg =
+ div_u64(se_runnable(se) * se->avg.runnable_load_sum, divider);
+ } while (0);
+#endif
+
+ enqueue_load_avg(cfs_rq, se);
+ if (se->on_rq) {
+ account_entity_enqueue(cfs_rq, se);
+ enqueue_runnable_load_avg(cfs_rq, se);
+ }
+}
+
+void reweight_task(struct task_struct *p, int prio)
+{
+ struct sched_entity *se = &p->se;
+ struct cfs_rq *cfs_rq = cfs_rq_of(se);
+ struct load_weight *load = &se->load;
+ unsigned long weight = scale_load(sched_prio_to_weight[prio]);
+
+ reweight_entity(cfs_rq, se, weight, weight);
+ load->inv_weight = sched_prio_to_wmult[prio];
+}
+
#ifdef CONFIG_FAIR_GROUP_SCHED
# ifdef CONFIG_SMP
-static long calc_cfs_shares(struct cfs_rq *cfs_rq, struct task_group *tg)
+/*
+ * All this does is approximate the hierarchical proportion which includes that
+ * global sum we all love to hate.
+ *
+ * That is, the weight of a group entity, is the proportional share of the
+ * group weight based on the group runqueue weights. That is:
+ *
+ * tg->weight * grq->load.weight
+ * ge->load.weight = ----------------------------- (1)
+ * \Sum grq->load.weight
+ *
+ * Now, because computing that sum is prohibitively expensive to compute (been
+ * there, done that) we approximate it with this average stuff. The average
+ * moves slower and therefore the approximation is cheaper and more stable.
+ *
+ * So instead of the above, we substitute:
+ *
+ * grq->load.weight -> grq->avg.load_avg (2)
+ *
+ * which yields the following:
+ *
+ * tg->weight * grq->avg.load_avg
+ * ge->load.weight = ------------------------------ (3)
+ * tg->load_avg
+ *
+ * Where: tg->load_avg ~= \Sum grq->avg.load_avg
+ *
+ * That is shares_avg, and it is right (given the approximation (2)).
+ *
+ * The problem with it is that because the average is slow -- it was designed
+ * to be exactly that of course -- this leads to transients in boundary
+ * conditions. In specific, the case where the group was idle and we start the
+ * one task. It takes time for our CPU's grq->avg.load_avg to build up,
+ * yielding bad latency etc..
+ *
+ * Now, in that special case (1) reduces to:
+ *
+ * tg->weight * grq->load.weight
+ * ge->load.weight = ----------------------------- = tg->weight (4)
+ * grp->load.weight
+ *
+ * That is, the sum collapses because all other CPUs are idle; the UP scenario.
+ *
+ * So what we do is modify our approximation (3) to approach (4) in the (near)
+ * UP case, like:
+ *
+ * ge->load.weight =
+ *
+ * tg->weight * grq->load.weight
+ * --------------------------------------------------- (5)
+ * tg->load_avg - grq->avg.load_avg + grq->load.weight
+ *
+ * But because grq->load.weight can drop to 0, resulting in a divide by zero,
+ * we need to use grq->avg.load_avg as its lower bound, which then gives:
+ *
+ *
+ * tg->weight * grq->load.weight
+ * ge->load.weight = ----------------------------- (6)
+ * tg_load_avg'
+ *
+ * Where:
+ *
+ * tg_load_avg' = tg->load_avg - grq->avg.load_avg +
+ * max(grq->load.weight, grq->avg.load_avg)
+ *
+ * And that is shares_weight and is icky. In the (near) UP case it approaches
+ * (4) while in the normal case it approaches (3). It consistently
+ * overestimates the ge->load.weight and therefore:
+ *
+ * \Sum ge->load.weight >= tg->weight
+ *
+ * hence icky!
+ */
+static long calc_group_shares(struct cfs_rq *cfs_rq)
{
- long tg_weight, load, shares;
+ long tg_weight, tg_shares, load, shares;
+ struct task_group *tg = cfs_rq->tg;
- /*
- * This really should be: cfs_rq->avg.load_avg, but instead we use
- * cfs_rq->load.weight, which is its upper bound. This helps ramp up
- * the shares for small weight interactive tasks.
- */
- load = scale_load_down(cfs_rq->load.weight);
+ tg_shares = READ_ONCE(tg->shares);
+
+ load = max(scale_load_down(cfs_rq->load.weight), cfs_rq->avg.load_avg);
tg_weight = atomic_long_read(&tg->load_avg);
@@ -2712,7 +2912,7 @@ static long calc_cfs_shares(struct cfs_rq *cfs_rq, struct task_group *tg)
tg_weight -= cfs_rq->tg_load_avg_contrib;
tg_weight += load;
- shares = (tg->shares * load);
+ shares = (tg_shares * load);
if (tg_weight)
shares /= tg_weight;
@@ -2728,63 +2928,86 @@ static long calc_cfs_shares(struct cfs_rq *cfs_rq, struct task_group *tg)
* case no task is runnable on a CPU MIN_SHARES=2 should be returned
* instead of 0.
*/
- if (shares < MIN_SHARES)
- shares = MIN_SHARES;
- if (shares > tg->shares)
- shares = tg->shares;
-
- return shares;
-}
-# else /* CONFIG_SMP */
-static inline long calc_cfs_shares(struct cfs_rq *cfs_rq, struct task_group *tg)
-{
- return tg->shares;
+ return clamp_t(long, shares, MIN_SHARES, tg_shares);
}
-# endif /* CONFIG_SMP */
-static void reweight_entity(struct cfs_rq *cfs_rq, struct sched_entity *se,
- unsigned long weight)
+/*
+ * This calculates the effective runnable weight for a group entity based on
+ * the group entity weight calculated above.
+ *
+ * Because of the above approximation (2), our group entity weight is
+ * an load_avg based ratio (3). This means that it includes blocked load and
+ * does not represent the runnable weight.
+ *
+ * Approximate the group entity's runnable weight per ratio from the group
+ * runqueue:
+ *
+ * grq->avg.runnable_load_avg
+ * ge->runnable_weight = ge->load.weight * -------------------------- (7)
+ * grq->avg.load_avg
+ *
+ * However, analogous to above, since the avg numbers are slow, this leads to
+ * transients in the from-idle case. Instead we use:
+ *
+ * ge->runnable_weight = ge->load.weight *
+ *
+ * max(grq->avg.runnable_load_avg, grq->runnable_weight)
+ * ----------------------------------------------------- (8)
+ * max(grq->avg.load_avg, grq->load.weight)
+ *
+ * Where these max() serve both to use the 'instant' values to fix the slow
+ * from-idle and avoid the /0 on to-idle, similar to (6).
+ */
+static long calc_group_runnable(struct cfs_rq *cfs_rq, long shares)
{
- if (se->on_rq) {
- /* commit outstanding execution time */
- if (cfs_rq->curr == se)
- update_curr(cfs_rq);
- account_entity_dequeue(cfs_rq, se);
- }
+ long runnable, load_avg;
- update_load_set(&se->load, weight);
+ load_avg = max(cfs_rq->avg.load_avg,
+ scale_load_down(cfs_rq->load.weight));
- if (se->on_rq)
- account_entity_enqueue(cfs_rq, se);
+ runnable = max(cfs_rq->avg.runnable_load_avg,
+ scale_load_down(cfs_rq->runnable_weight));
+
+ runnable *= shares;
+ if (load_avg)
+ runnable /= load_avg;
+
+ return clamp_t(long, runnable, MIN_SHARES, shares);
}
+# endif /* CONFIG_SMP */
static inline int throttled_hierarchy(struct cfs_rq *cfs_rq);
-static void update_cfs_shares(struct sched_entity *se)
+/*
+ * Recomputes the group entity based on the current state of its group
+ * runqueue.
+ */
+static void update_cfs_group(struct sched_entity *se)
{
- struct cfs_rq *cfs_rq = group_cfs_rq(se);
- struct task_group *tg;
- long shares;
+ struct cfs_rq *gcfs_rq = group_cfs_rq(se);
+ long shares, runnable;
- if (!cfs_rq)
+ if (!gcfs_rq)
return;
- if (throttled_hierarchy(cfs_rq))
+ if (throttled_hierarchy(gcfs_rq))
return;
- tg = cfs_rq->tg;
-
#ifndef CONFIG_SMP
- if (likely(se->load.weight == tg->shares))
+ runnable = shares = READ_ONCE(gcfs_rq->tg->shares);
+
+ if (likely(se->load.weight == shares))
return;
+#else
+ shares = calc_group_shares(gcfs_rq);
+ runnable = calc_group_runnable(gcfs_rq, shares);
#endif
- shares = calc_cfs_shares(cfs_rq, tg);
- reweight_entity(cfs_rq_of(se), se, shares);
+ reweight_entity(cfs_rq_of(se), se, shares, runnable);
}
#else /* CONFIG_FAIR_GROUP_SCHED */
-static inline void update_cfs_shares(struct sched_entity *se)
+static inline void update_cfs_group(struct sched_entity *se)
{
}
#endif /* CONFIG_FAIR_GROUP_SCHED */
@@ -2893,7 +3116,7 @@ static u32 __accumulate_pelt_segments(u64 periods, u32 d1, u32 d3)
*/
static __always_inline u32
accumulate_sum(u64 delta, int cpu, struct sched_avg *sa,
- unsigned long weight, int running, struct cfs_rq *cfs_rq)
+ unsigned long load, unsigned long runnable, int running)
{
unsigned long scale_freq, scale_cpu;
u32 contrib = (u32)delta; /* p == 0 -> delta < 1024 */
@@ -2910,10 +3133,8 @@ accumulate_sum(u64 delta, int cpu, struct sched_avg *sa,
*/
if (periods) {
sa->load_sum = decay_load(sa->load_sum, periods);
- if (cfs_rq) {
- cfs_rq->runnable_load_sum =
- decay_load(cfs_rq->runnable_load_sum, periods);
- }
+ sa->runnable_load_sum =
+ decay_load(sa->runnable_load_sum, periods);
sa->util_sum = decay_load((u64)(sa->util_sum), periods);
/*
@@ -2926,11 +3147,10 @@ accumulate_sum(u64 delta, int cpu, struct sched_avg *sa,
sa->period_contrib = delta;
contrib = cap_scale(contrib, scale_freq);
- if (weight) {
- sa->load_sum += weight * contrib;
- if (cfs_rq)
- cfs_rq->runnable_load_sum += weight * contrib;
- }
+ if (load)
+ sa->load_sum += load * contrib;
+ if (runnable)
+ sa->runnable_load_sum += runnable * contrib;
if (running)
sa->util_sum += contrib * scale_cpu;
@@ -2966,8 +3186,8 @@ accumulate_sum(u64 delta, int cpu, struct sched_avg *sa,
* = u_0 + u_1*y + u_2*y^2 + ... [re-labeling u_i --> u_{i+1}]
*/
static __always_inline int
-___update_load_avg(u64 now, int cpu, struct sched_avg *sa,
- unsigned long weight, int running, struct cfs_rq *cfs_rq)
+___update_load_sum(u64 now, int cpu, struct sched_avg *sa,
+ unsigned long load, unsigned long runnable, int running)
{
u64 delta;
@@ -3000,8 +3220,8 @@ ___update_load_avg(u64 now, int cpu, struct sched_avg *sa,
* this happens during idle_balance() which calls
* update_blocked_averages()
*/
- if (!weight)
- running = 0;
+ if (!load)
+ runnable = running = 0;
/*
* Now we know we crossed measurement unit boundaries. The *_avg
@@ -3010,63 +3230,96 @@ ___update_load_avg(u64 now, int cpu, struct sched_avg *sa,
* Step 1: accumulate *_sum since last_update_time. If we haven't
* crossed period boundaries, finish.
*/
- if (!accumulate_sum(delta, cpu, sa, weight, running, cfs_rq))
+ if (!accumulate_sum(delta, cpu, sa, load, runnable, running))
return 0;
+ return 1;
+}
+
+static __always_inline void
+___update_load_avg(struct sched_avg *sa, unsigned long load, unsigned long runnable)
+{
+ u32 divider = LOAD_AVG_MAX - 1024 + sa->period_contrib;
+
/*
* Step 2: update *_avg.
*/
- sa->load_avg = div_u64(sa->load_sum, LOAD_AVG_MAX - 1024 + sa->period_contrib);
- if (cfs_rq) {
- cfs_rq->runnable_load_avg =
- div_u64(cfs_rq->runnable_load_sum, LOAD_AVG_MAX - 1024 + sa->period_contrib);
- }
- sa->util_avg = sa->util_sum / (LOAD_AVG_MAX - 1024 + sa->period_contrib);
-
- return 1;
+ sa->load_avg = div_u64(load * sa->load_sum, divider);
+ sa->runnable_load_avg = div_u64(runnable * sa->runnable_load_sum, divider);
+ sa->util_avg = sa->util_sum / divider;
}
+/*
+ * sched_entity:
+ *
+ * task:
+ * se_runnable() == se_weight()
+ *
+ * group: [ see update_cfs_group() ]
+ * se_weight() = tg->weight * grq->load_avg / tg->load_avg
+ * se_runnable() = se_weight(se) * grq->runnable_load_avg / grq->load_avg
+ *
+ * load_sum := runnable_sum
+ * load_avg = se_weight(se) * runnable_avg
+ *
+ * runnable_load_sum := runnable_sum
+ * runnable_load_avg = se_runnable(se) * runnable_avg
+ *
+ * XXX collapse load_sum and runnable_load_sum
+ *
+ * cfq_rs:
+ *
+ * load_sum = \Sum se_weight(se) * se->avg.load_sum
+ * load_avg = \Sum se->avg.load_avg
+ *
+ * runnable_load_sum = \Sum se_runnable(se) * se->avg.runnable_load_sum
+ * runnable_load_avg = \Sum se->avg.runable_load_avg
+ */
+
static int
__update_load_avg_blocked_se(u64 now, int cpu, struct sched_entity *se)
{
- return ___update_load_avg(now, cpu, &se->avg, 0, 0, NULL);
+ if (entity_is_task(se))
+ se->runnable_weight = se->load.weight;
+
+ if (___update_load_sum(now, cpu, &se->avg, 0, 0, 0)) {
+ ___update_load_avg(&se->avg, se_weight(se), se_runnable(se));
+ return 1;
+ }
+
+ return 0;
}
static int
__update_load_avg_se(u64 now, int cpu, struct cfs_rq *cfs_rq, struct sched_entity *se)
{
- return ___update_load_avg(now, cpu, &se->avg,
- se->on_rq * scale_load_down(se->load.weight),
- cfs_rq->curr == se, NULL);
+ if (entity_is_task(se))
+ se->runnable_weight = se->load.weight;
+
+ if (___update_load_sum(now, cpu, &se->avg, !!se->on_rq, !!se->on_rq,
+ cfs_rq->curr == se)) {
+
+ ___update_load_avg(&se->avg, se_weight(se), se_runnable(se));
+ return 1;
+ }
+
+ return 0;
}
static int
__update_load_avg_cfs_rq(u64 now, int cpu, struct cfs_rq *cfs_rq)
{
- return ___update_load_avg(now, cpu, &cfs_rq->avg,
- scale_load_down(cfs_rq->load.weight),
- cfs_rq->curr != NULL, cfs_rq);
-}
+ if (___update_load_sum(now, cpu, &cfs_rq->avg,
+ scale_load_down(cfs_rq->load.weight),
+ scale_load_down(cfs_rq->runnable_weight),
+ cfs_rq->curr != NULL)) {
-/*
- * Signed add and clamp on underflow.
- *
- * Explicitly do a load-store to ensure the intermediate value never hits
- * memory. This allows lockless observations without ever seeing the negative
- * values.
- */
-#define add_positive(_ptr, _val) do { \
- typeof(_ptr) ptr = (_ptr); \
- typeof(_val) val = (_val); \
- typeof(*ptr) res, var = READ_ONCE(*ptr); \
- \
- res = var + val; \
- \
- if (val < 0 && res > var) \
- res = 0; \
- \
- WRITE_ONCE(*ptr, res); \
-} while (0)
+ ___update_load_avg(&cfs_rq->avg, 1, 1);
+ return 1;
+ }
+
+ return 0;
+}
#ifdef CONFIG_FAIR_GROUP_SCHED
/**
@@ -3149,11 +3402,77 @@ void set_task_rq_fair(struct sched_entity *se,
se->avg.last_update_time = n_last_update_time;
}
-/* Take into account change of utilization of a child task group */
+
+/*
+ * When on migration a sched_entity joins/leaves the PELT hierarchy, we need to
+ * propagate its contribution. The key to this propagation is the invariant
+ * that for each group:
+ *
+ * ge->avg == grq->avg (1)
+ *
+ * _IFF_ we look at the pure running and runnable sums. Because they
+ * represent the very same entity, just at different points in the hierarchy.
+ *
+ *
+ * Per the above update_tg_cfs_util() is trivial (and still 'wrong') and
+ * simply copies the running sum over.
+ *
+ * However, update_tg_cfs_runnable() is more complex. So we have:
+ *
+ * ge->avg.load_avg = ge->load.weight * ge->avg.runnable_avg (2)
+ *
+ * And since, like util, the runnable part should be directly transferable,
+ * the following would _appear_ to be the straight forward approach:
+ *
+ * grq->avg.load_avg = grq->load.weight * grq->avg.running_avg (3)
+ *
+ * And per (1) we have:
+ *
+ * ge->avg.running_avg == grq->avg.running_avg
+ *
+ * Which gives:
+ *
+ * ge->load.weight * grq->avg.load_avg
+ * ge->avg.load_avg = ----------------------------------- (4)
+ * grq->load.weight
+ *
+ * Except that is wrong!
+ *
+ * Because while for entities historical weight is not important and we
+ * really only care about our future and therefore can consider a pure
+ * runnable sum, runqueues can NOT do this.
+ *
+ * We specifically want runqueues to have a load_avg that includes
+ * historical weights. Those represent the blocked load, the load we expect
+ * to (shortly) return to us. This only works by keeping the weights as
+ * integral part of the sum. We therefore cannot decompose as per (3).
+ *
+ * OK, so what then?
+ *
+ *
+ * Another way to look at things is:
+ *
+ * grq->avg.load_avg = \Sum se->avg.load_avg
+ *
+ * Therefore, per (2):
+ *
+ * grq->avg.load_avg = \Sum se->load.weight * se->avg.runnable_avg
+ *
+ * And the very thing we're propagating is a change in that sum (someone
+ * joined/left). So we can easily know the runnable change, which would be, per
+ * (2) the already tracked se->load_avg divided by the corresponding
+ * se->weight.
+ *
+ * Basically (4) but in differential form:
+ *
+ * d(runnable_avg) += se->avg.load_avg / se->load.weight
+ * (5)
+ * ge->avg.load_avg += ge->load.weight * d(runnable_avg)
+ */
+
static inline void
-update_tg_cfs_util(struct cfs_rq *cfs_rq, struct sched_entity *se)
+update_tg_cfs_util(struct cfs_rq *cfs_rq, struct sched_entity *se, struct cfs_rq *gcfs_rq)
{
- struct cfs_rq *gcfs_rq = group_cfs_rq(se);
long delta = gcfs_rq->avg.util_avg - se->avg.util_avg;
/* Nothing to update */
@@ -3169,102 +3488,65 @@ update_tg_cfs_util(struct cfs_rq *cfs_rq, struct sched_entity *se)
cfs_rq->avg.util_sum = cfs_rq->avg.util_avg * LOAD_AVG_MAX;
}
-/* Take into account change of load of a child task group */
static inline void
-update_tg_cfs_load(struct cfs_rq *cfs_rq, struct sched_entity *se)
+update_tg_cfs_runnable(struct cfs_rq *cfs_rq, struct sched_entity *se, struct cfs_rq *gcfs_rq)
{
- struct cfs_rq *gcfs_rq = group_cfs_rq(se);
- long delta, load = gcfs_rq->avg.load_avg;
+ long runnable_sum = gcfs_rq->prop_runnable_sum;
+ long runnable_load_avg, load_avg;
+ s64 runnable_load_sum, load_sum;
- /*
- * If the load of group cfs_rq is null, the load of the
- * sched_entity will also be null so we can skip the formula
- */
- if (load) {
- long tg_load;
+ if (!runnable_sum)
+ return;
- /* Get tg's load and ensure tg_load > 0 */
- tg_load = atomic_long_read(&gcfs_rq->tg->load_avg) + 1;
+ gcfs_rq->prop_runnable_sum = 0;
- /* Ensure tg_load >= load and updated with current load*/
- tg_load -= gcfs_rq->tg_load_avg_contrib;
- tg_load += load;
+ load_sum = (s64)se_weight(se) * runnable_sum;
+ load_avg = div_s64(load_sum, LOAD_AVG_MAX);
- /*
- * We need to compute a correction term in the case that the
- * task group is consuming more CPU than a task of equal
- * weight. A task with a weight equals to tg->shares will have
- * a load less or equal to scale_load_down(tg->shares).
- * Similarly, the sched_entities that represent the task group
- * at parent level, can't have a load higher than
- * scale_load_down(tg->shares). And the Sum of sched_entities'
- * load must be <= scale_load_down(tg->shares).
- */
- if (tg_load > scale_load_down(gcfs_rq->tg->shares)) {
- /* scale gcfs_rq's load into tg's shares*/
- load *= scale_load_down(gcfs_rq->tg->shares);
- load /= tg_load;
- }
- }
+ add_positive(&se->avg.load_sum, runnable_sum);
+ add_positive(&se->avg.load_avg, load_avg);
- delta = load - se->avg.load_avg;
+ add_positive(&cfs_rq->avg.load_avg, load_avg);
+ add_positive(&cfs_rq->avg.load_sum, load_sum);
- /* Nothing to update */
- if (!delta)
- return;
-
- /* Set new sched_entity's load */
- se->avg.load_avg = load;
- se->avg.load_sum = se->avg.load_avg * LOAD_AVG_MAX;
+ runnable_load_sum = (s64)se_runnable(se) * runnable_sum;
+ runnable_load_avg = div_s64(runnable_load_sum, LOAD_AVG_MAX);
- /* Update parent cfs_rq load */
- add_positive(&cfs_rq->avg.load_avg, delta);
- cfs_rq->avg.load_sum = cfs_rq->avg.load_avg * LOAD_AVG_MAX;
+ add_positive(&se->avg.runnable_load_sum, runnable_sum);
+ add_positive(&se->avg.runnable_load_avg, runnable_load_avg);
- /*
- * If the sched_entity is already enqueued, we also have to update the
- * runnable load avg.
- */
if (se->on_rq) {
- /* Update parent cfs_rq runnable_load_avg */
- add_positive(&cfs_rq->runnable_load_avg, delta);
- cfs_rq->runnable_load_sum = cfs_rq->runnable_load_avg * LOAD_AVG_MAX;
+ add_positive(&cfs_rq->avg.runnable_load_avg, runnable_load_avg);
+ add_positive(&cfs_rq->avg.runnable_load_sum, runnable_load_sum);
}
}
-static inline void set_tg_cfs_propagate(struct cfs_rq *cfs_rq)
-{
- cfs_rq->propagate_avg = 1;
-}
-
-static inline int test_and_clear_tg_cfs_propagate(struct sched_entity *se)
+static inline void add_tg_cfs_propagate(struct cfs_rq *cfs_rq, long runnable_sum)
{
- struct cfs_rq *cfs_rq = group_cfs_rq(se);
-
- if (!cfs_rq->propagate_avg)
- return 0;
-
- cfs_rq->propagate_avg = 0;
- return 1;
+ cfs_rq->propagate = 1;
+ cfs_rq->prop_runnable_sum += runnable_sum;
}
/* Update task and its cfs_rq load average */
static inline int propagate_entity_load_avg(struct sched_entity *se)
{
- struct cfs_rq *cfs_rq;
+ struct cfs_rq *cfs_rq, *gcfs_rq;
if (entity_is_task(se))
return 0;
- if (!test_and_clear_tg_cfs_propagate(se))
+ gcfs_rq = group_cfs_rq(se);
+ if (!gcfs_rq->propagate)
return 0;
+ gcfs_rq->propagate = 0;
+
cfs_rq = cfs_rq_of(se);
- set_tg_cfs_propagate(cfs_rq);
+ add_tg_cfs_propagate(cfs_rq, gcfs_rq->prop_runnable_sum);
- update_tg_cfs_util(cfs_rq, se);
- update_tg_cfs_load(cfs_rq, se);
+ update_tg_cfs_util(cfs_rq, se, gcfs_rq);
+ update_tg_cfs_runnable(cfs_rq, se, gcfs_rq);
return 1;
}
@@ -3288,7 +3570,7 @@ static inline bool skip_blocked_update(struct sched_entity *se)
* If there is a pending propagation, we have to update the load and
* the utilization of the sched_entity:
*/
- if (gcfs_rq->propagate_avg)
+ if (gcfs_rq->propagate)
return false;
/*
@@ -3308,27 +3590,10 @@ static inline int propagate_entity_load_avg(struct sched_entity *se)
return 0;
}
-static inline void set_tg_cfs_propagate(struct cfs_rq *cfs_rq) {}
+static inline void add_tg_cfs_propagate(struct cfs_rq *cfs_rq, long runnable_sum) {}
#endif /* CONFIG_FAIR_GROUP_SCHED */
-/*
- * Unsigned subtract and clamp on underflow.
- *
- * Explicitly do a load-store to ensure the intermediate value never hits
- * memory. This allows lockless observations without ever seeing the negative
- * values.
- */
-#define sub_positive(_ptr, _val) do { \
- typeof(_ptr) ptr = (_ptr); \
- typeof(*ptr) val = (_val); \
- typeof(*ptr) res, var = READ_ONCE(*ptr); \
- res = var - val; \
- if (res > var) \
- res = 0; \
- WRITE_ONCE(*ptr, res); \
-} while (0)
-
/**
* update_cfs_rq_load_avg - update the cfs_rq's load/util averages
* @now: current time, as per cfs_rq_clock_task()
@@ -3348,65 +3613,45 @@ static inline void set_tg_cfs_propagate(struct cfs_rq *cfs_rq) {}
static inline int
update_cfs_rq_load_avg(u64 now, struct cfs_rq *cfs_rq)
{
+ unsigned long removed_load = 0, removed_util = 0, removed_runnable_sum = 0;
struct sched_avg *sa = &cfs_rq->avg;
- int decayed, removed_load = 0, removed_util = 0;
+ int decayed = 0;
- if (atomic_long_read(&cfs_rq->removed_load_avg)) {
- s64 r = atomic_long_xchg(&cfs_rq->removed_load_avg, 0);
+ if (cfs_rq->removed.nr) {
+ unsigned long r;
+ u32 divider = LOAD_AVG_MAX - 1024 + sa->period_contrib;
+
+ raw_spin_lock(&cfs_rq->removed.lock);
+ swap(cfs_rq->removed.util_avg, removed_util);
+ swap(cfs_rq->removed.load_avg, removed_load);
+ swap(cfs_rq->removed.runnable_sum, removed_runnable_sum);
+ cfs_rq->removed.nr = 0;
+ raw_spin_unlock(&cfs_rq->removed.lock);
+
+ r = removed_load;
sub_positive(&sa->load_avg, r);
- sub_positive(&sa->load_sum, r * LOAD_AVG_MAX);
- removed_load = 1;
- set_tg_cfs_propagate(cfs_rq);
- }
+ sub_positive(&sa->load_sum, r * divider);
- if (atomic_long_read(&cfs_rq->removed_util_avg)) {
- long r = atomic_long_xchg(&cfs_rq->removed_util_avg, 0);
+ r = removed_util;
sub_positive(&sa->util_avg, r);
- sub_positive(&sa->util_sum, r * LOAD_AVG_MAX);
- removed_util = 1;
- set_tg_cfs_propagate(cfs_rq);
+ sub_positive(&sa->util_sum, r * divider);
+
+ add_tg_cfs_propagate(cfs_rq, -(long)removed_runnable_sum);
+
+ decayed = 1;
}
- decayed = __update_load_avg_cfs_rq(now, cpu_of(rq_of(cfs_rq)), cfs_rq);
+ decayed |= __update_load_avg_cfs_rq(now, cpu_of(rq_of(cfs_rq)), cfs_rq);
#ifndef CONFIG_64BIT
smp_wmb();
cfs_rq->load_last_update_time_copy = sa->last_update_time;
#endif
- if (decayed || removed_util)
+ if (decayed)
cfs_rq_util_change(cfs_rq);
- return decayed || removed_load;
-}
-
-/*
- * Optional action to be done while updating the load average
- */
-#define UPDATE_TG 0x1
-#define SKIP_AGE_LOAD 0x2
-
-/* Update task and its cfs_rq load average */
-static inline void update_load_avg(struct sched_entity *se, int flags)
-{
- struct cfs_rq *cfs_rq = cfs_rq_of(se);
- u64 now = cfs_rq_clock_task(cfs_rq);
- struct rq *rq = rq_of(cfs_rq);
- int cpu = cpu_of(rq);
- int decayed;
-
- /*
- * Track task load average for carrying it to new CPU after migrated, and
- * track group sched_entity load average for task_h_load calc in migration
- */
- if (se->avg.last_update_time && !(flags & SKIP_AGE_LOAD))
- __update_load_avg_se(now, cpu, cfs_rq, se);
-
- decayed = update_cfs_rq_load_avg(now, cfs_rq);
- decayed |= propagate_entity_load_avg(se);
-
- if (decayed && (flags & UPDATE_TG))
- update_tg_load_avg(cfs_rq, 0);
+ return decayed;
}
/**
@@ -3419,12 +3664,39 @@ static inline void update_load_avg(struct sched_entity *se, int flags)
*/
static void attach_entity_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se)
{
+ u32 divider = LOAD_AVG_MAX - 1024 + cfs_rq->avg.period_contrib;
+
+ /*
+ * When we attach the @se to the @cfs_rq, we must align the decay
+ * window because without that, really weird and wonderful things can
+ * happen.
+ *
+ * XXX illustrate
+ */
se->avg.last_update_time = cfs_rq->avg.last_update_time;
- cfs_rq->avg.load_avg += se->avg.load_avg;
- cfs_rq->avg.load_sum += se->avg.load_sum;
+ se->avg.period_contrib = cfs_rq->avg.period_contrib;
+
+ /*
+ * Hell(o) Nasty stuff.. we need to recompute _sum based on the new
+ * period_contrib. This isn't strictly correct, but since we're
+ * entirely outside of the PELT hierarchy, nobody cares if we truncate
+ * _sum a little.
+ */
+ se->avg.util_sum = se->avg.util_avg * divider;
+
+ se->avg.load_sum = divider;
+ if (se_weight(se)) {
+ se->avg.load_sum =
+ div_u64(se->avg.load_avg * se->avg.load_sum, se_weight(se));
+ }
+
+ se->avg.runnable_load_sum = se->avg.load_sum;
+
+ enqueue_load_avg(cfs_rq, se);
cfs_rq->avg.util_avg += se->avg.util_avg;
cfs_rq->avg.util_sum += se->avg.util_sum;
- set_tg_cfs_propagate(cfs_rq);
+
+ add_tg_cfs_propagate(cfs_rq, se->avg.load_sum);
cfs_rq_util_change(cfs_rq);
}
@@ -3439,39 +3711,47 @@ static void attach_entity_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *s
*/
static void detach_entity_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se)
{
-
- sub_positive(&cfs_rq->avg.load_avg, se->avg.load_avg);
- sub_positive(&cfs_rq->avg.load_sum, se->avg.load_sum);
+ dequeue_load_avg(cfs_rq, se);
sub_positive(&cfs_rq->avg.util_avg, se->avg.util_avg);
sub_positive(&cfs_rq->avg.util_sum, se->avg.util_sum);
- set_tg_cfs_propagate(cfs_rq);
+
+ add_tg_cfs_propagate(cfs_rq, -se->avg.load_sum);
cfs_rq_util_change(cfs_rq);
}
-/* Add the load generated by se into cfs_rq's load average */
-static inline void
-enqueue_entity_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se)
+/*
+ * Optional action to be done while updating the load average
+ */
+#define UPDATE_TG 0x1
+#define SKIP_AGE_LOAD 0x2
+#define DO_ATTACH 0x4
+
+/* Update task and its cfs_rq load average */
+static inline void update_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se, int flags)
{
- struct sched_avg *sa = &se->avg;
+ u64 now = cfs_rq_clock_task(cfs_rq);
+ struct rq *rq = rq_of(cfs_rq);
+ int cpu = cpu_of(rq);
+ int decayed;
+
+ /*
+ * Track task load average for carrying it to new CPU after migrated, and
+ * track group sched_entity load average for task_h_load calc in migration
+ */
+ if (se->avg.last_update_time && !(flags & SKIP_AGE_LOAD))
+ __update_load_avg_se(now, cpu, cfs_rq, se);
- cfs_rq->runnable_load_avg += sa->load_avg;
- cfs_rq->runnable_load_sum += sa->load_sum;
+ decayed = update_cfs_rq_load_avg(now, cfs_rq);
+ decayed |= propagate_entity_load_avg(se);
+
+ if (!se->avg.last_update_time && (flags & DO_ATTACH)) {
- if (!sa->last_update_time) {
attach_entity_load_avg(cfs_rq, se);
update_tg_load_avg(cfs_rq, 0);
- }
-}
-/* Remove the runnable load generated by se from cfs_rq's runnable load average */
-static inline void
-dequeue_entity_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se)
-{
- cfs_rq->runnable_load_avg =
- max_t(long, cfs_rq->runnable_load_avg - se->avg.load_avg, 0);
- cfs_rq->runnable_load_sum =
- max_t(s64, cfs_rq->runnable_load_sum - se->avg.load_sum, 0);
+ } else if (decayed && (flags & UPDATE_TG))
+ update_tg_load_avg(cfs_rq, 0);
}
#ifndef CONFIG_64BIT
@@ -3515,6 +3795,7 @@ void sync_entity_load_avg(struct sched_entity *se)
void remove_entity_load_avg(struct sched_entity *se)
{
struct cfs_rq *cfs_rq = cfs_rq_of(se);
+ unsigned long flags;
/*
* tasks cannot exit without having gone through wake_up_new_task() ->
@@ -3527,13 +3808,18 @@ void remove_entity_load_avg(struct sched_entity *se)
*/
sync_entity_load_avg(se);
- atomic_long_add(se->avg.load_avg, &cfs_rq->removed_load_avg);
- atomic_long_add(se->avg.util_avg, &cfs_rq->removed_util_avg);
+
+ raw_spin_lock_irqsave(&cfs_rq->removed.lock, flags);
+ ++cfs_rq->removed.nr;
+ cfs_rq->removed.util_avg += se->avg.util_avg;
+ cfs_rq->removed.load_avg += se->avg.load_avg;
+ cfs_rq->removed.runnable_sum += se->avg.load_sum; /* == runnable_sum */
+ raw_spin_unlock_irqrestore(&cfs_rq->removed.lock, flags);
}
static inline unsigned long cfs_rq_runnable_load_avg(struct cfs_rq *cfs_rq)
{
- return cfs_rq->runnable_load_avg;
+ return cfs_rq->avg.runnable_load_avg;
}
static inline unsigned long cfs_rq_load_avg(struct cfs_rq *cfs_rq)
@@ -3553,16 +3839,13 @@ update_cfs_rq_load_avg(u64 now, struct cfs_rq *cfs_rq)
#define UPDATE_TG 0x0
#define SKIP_AGE_LOAD 0x0
+#define DO_ATTACH 0x0
-static inline void update_load_avg(struct sched_entity *se, int not_used1)
+static inline void update_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se, int not_used1)
{
- cfs_rq_util_change(cfs_rq_of(se));
+ cfs_rq_util_change(cfs_rq);
}
-static inline void
-enqueue_entity_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se) {}
-static inline void
-dequeue_entity_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se) {}
static inline void remove_entity_load_avg(struct sched_entity *se) {}
static inline void
@@ -3707,9 +3990,9 @@ enqueue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int flags)
* its group cfs_rq
* - Add its new weight to cfs_rq->load.weight
*/
- update_load_avg(se, UPDATE_TG);
- enqueue_entity_load_avg(cfs_rq, se);
- update_cfs_shares(se);
+ update_load_avg(cfs_rq, se, UPDATE_TG | DO_ATTACH);
+ update_cfs_group(se);
+ enqueue_runnable_load_avg(cfs_rq, se);
account_entity_enqueue(cfs_rq, se);
if (flags & ENQUEUE_WAKEUP)
@@ -3791,8 +4074,8 @@ dequeue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int flags)
* - For group entity, update its weight to reflect the new share
* of its group cfs_rq.
*/
- update_load_avg(se, UPDATE_TG);
- dequeue_entity_load_avg(cfs_rq, se);
+ update_load_avg(cfs_rq, se, UPDATE_TG);
+ dequeue_runnable_load_avg(cfs_rq, se);
update_stats_dequeue(cfs_rq, se, flags);
@@ -3815,7 +4098,7 @@ dequeue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int flags)
/* return excess runtime on last dequeue */
return_cfs_rq_runtime(cfs_rq);
- update_cfs_shares(se);
+ update_cfs_group(se);
/*
* Now advance min_vruntime if @se was the entity holding it back,
@@ -3879,7 +4162,7 @@ set_next_entity(struct cfs_rq *cfs_rq, struct sched_entity *se)
*/
update_stats_wait_end(cfs_rq, se);
__dequeue_entity(cfs_rq, se);
- update_load_avg(se, UPDATE_TG);
+ update_load_avg(cfs_rq, se, UPDATE_TG);
}
update_stats_curr_start(cfs_rq, se);
@@ -3981,7 +4264,7 @@ static void put_prev_entity(struct cfs_rq *cfs_rq, struct sched_entity *prev)
/* Put 'current' back into the tree. */
__enqueue_entity(cfs_rq, prev);
/* in !on_rq case, update occurred at dequeue */
- update_load_avg(prev, 0);
+ update_load_avg(cfs_rq, prev, 0);
}
cfs_rq->curr = NULL;
}
@@ -3997,8 +4280,8 @@ entity_tick(struct cfs_rq *cfs_rq, struct sched_entity *curr, int queued)
/*
* Ensure that runnable average is periodically updated.
*/
- update_load_avg(curr, UPDATE_TG);
- update_cfs_shares(curr);
+ update_load_avg(cfs_rq, curr, UPDATE_TG);
+ update_cfs_group(curr);
#ifdef CONFIG_SCHED_HRTICK
/*
@@ -4915,8 +5198,8 @@ enqueue_task_fair(struct rq *rq, struct task_struct *p, int flags)
if (cfs_rq_throttled(cfs_rq))
break;
- update_load_avg(se, UPDATE_TG);
- update_cfs_shares(se);
+ update_load_avg(cfs_rq, se, UPDATE_TG);
+ update_cfs_group(se);
}
if (!se)
@@ -4974,8 +5257,8 @@ static void dequeue_task_fair(struct rq *rq, struct task_struct *p, int flags)
if (cfs_rq_throttled(cfs_rq))
break;
- update_load_avg(se, UPDATE_TG);
- update_cfs_shares(se);
+ update_load_avg(cfs_rq, se, UPDATE_TG);
+ update_cfs_group(se);
}
if (!se)
@@ -5449,6 +5732,8 @@ static unsigned long capacity_spare_wake(int cpu, struct task_struct *p)
/*
* find_idlest_group finds and returns the least busy CPU group within the
* domain.
+ *
+ * Assumes p is allowed on at least one CPU in sd.
*/
static struct sched_group *
find_idlest_group(struct sched_domain *sd, struct task_struct *p,
@@ -5456,8 +5741,9 @@ find_idlest_group(struct sched_domain *sd, struct task_struct *p,
{
struct sched_group *idlest = NULL, *group = sd->groups;
struct sched_group *most_spare_sg = NULL;
- unsigned long min_runnable_load = ULONG_MAX, this_runnable_load = 0;
- unsigned long min_avg_load = ULONG_MAX, this_avg_load = 0;
+ unsigned long min_runnable_load = ULONG_MAX;
+ unsigned long this_runnable_load = ULONG_MAX;
+ unsigned long min_avg_load = ULONG_MAX, this_avg_load = ULONG_MAX;
unsigned long most_spare = 0, this_spare = 0;
int load_idx = sd->forkexec_idx;
int imbalance_scale = 100 + (sd->imbalance_pct-100)/2;
@@ -5578,10 +5864,10 @@ skip_spare:
}
/*
- * find_idlest_cpu - find the idlest cpu among the cpus in group.
+ * find_idlest_group_cpu - find the idlest cpu among the cpus in group.
*/
static int
-find_idlest_cpu(struct sched_group *group, struct task_struct *p, int this_cpu)
+find_idlest_group_cpu(struct sched_group *group, struct task_struct *p, int this_cpu)
{
unsigned long load, min_load = ULONG_MAX;
unsigned int min_exit_latency = UINT_MAX;
@@ -5630,6 +5916,53 @@ find_idlest_cpu(struct sched_group *group, struct task_struct *p, int this_cpu)
return shallowest_idle_cpu != -1 ? shallowest_idle_cpu : least_loaded_cpu;
}
+static inline int find_idlest_cpu(struct sched_domain *sd, struct task_struct *p,
+ int cpu, int prev_cpu, int sd_flag)
+{
+ int new_cpu = cpu;
+
+ if (!cpumask_intersects(sched_domain_span(sd), &p->cpus_allowed))
+ return prev_cpu;
+
+ while (sd) {
+ struct sched_group *group;
+ struct sched_domain *tmp;
+ int weight;
+
+ if (!(sd->flags & sd_flag)) {
+ sd = sd->child;
+ continue;
+ }
+
+ group = find_idlest_group(sd, p, cpu, sd_flag);
+ if (!group) {
+ sd = sd->child;
+ continue;
+ }
+
+ new_cpu = find_idlest_group_cpu(group, p, cpu);
+ if (new_cpu == cpu) {
+ /* Now try balancing at a lower domain level of cpu */
+ sd = sd->child;
+ continue;
+ }
+
+ /* Now try balancing at a lower domain level of new_cpu */
+ cpu = new_cpu;
+ weight = sd->span_weight;
+ sd = NULL;
+ for_each_domain(cpu, tmp) {
+ if (weight <= tmp->span_weight)
+ break;
+ if (tmp->flags & sd_flag)
+ sd = tmp;
+ }
+ /* while loop will break here if sd == NULL */
+ }
+
+ return new_cpu;
+}
+
#ifdef CONFIG_SCHED_SMT
static inline void set_idle_cores(int cpu, int val)
@@ -5982,50 +6315,30 @@ select_task_rq_fair(struct task_struct *p, int prev_cpu, int sd_flag, int wake_f
new_cpu = cpu;
}
+ if (sd && !(sd_flag & SD_BALANCE_FORK)) {
+ /*
+ * We're going to need the task's util for capacity_spare_wake
+ * in find_idlest_group. Sync it up to prev_cpu's
+ * last_update_time.
+ */
+ sync_entity_load_avg(&p->se);
+ }
+
if (!sd) {
- pick_cpu:
+pick_cpu:
if (sd_flag & SD_BALANCE_WAKE) /* XXX always ? */
new_cpu = select_idle_sibling(p, prev_cpu, new_cpu);
- } else while (sd) {
- struct sched_group *group;
- int weight;
-
- if (!(sd->flags & sd_flag)) {
- sd = sd->child;
- continue;
- }
-
- group = find_idlest_group(sd, p, cpu, sd_flag);
- if (!group) {
- sd = sd->child;
- continue;
- }
-
- new_cpu = find_idlest_cpu(group, p, cpu);
- if (new_cpu == -1 || new_cpu == cpu) {
- /* Now try balancing at a lower domain level of cpu */
- sd = sd->child;
- continue;
- }
-
- /* Now try balancing at a lower domain level of new_cpu */
- cpu = new_cpu;
- weight = sd->span_weight;
- sd = NULL;
- for_each_domain(cpu, tmp) {
- if (weight <= tmp->span_weight)
- break;
- if (tmp->flags & sd_flag)
- sd = tmp;
- }
- /* while loop will break here if sd == NULL */
+ } else {
+ new_cpu = find_idlest_cpu(sd, p, cpu, prev_cpu, sd_flag);
}
rcu_read_unlock();
return new_cpu;
}
+static void detach_entity_cfs_rq(struct sched_entity *se);
+
/*
* Called immediately before a task is migrated to a new cpu; task_cpu(p) and
* cfs_rq_of(p) references at time of call are still valid and identify the
@@ -6059,14 +6372,25 @@ static void migrate_task_rq_fair(struct task_struct *p)
se->vruntime -= min_vruntime;
}
- /*
- * We are supposed to update the task to "current" time, then its up to date
- * and ready to go to new CPU/cfs_rq. But we have difficulty in getting
- * what current time is, so simply throw away the out-of-date time. This
- * will result in the wakee task is less decayed, but giving the wakee more
- * load sounds not bad.
- */
- remove_entity_load_avg(&p->se);
+ if (p->on_rq == TASK_ON_RQ_MIGRATING) {
+ /*
+ * In case of TASK_ON_RQ_MIGRATING we in fact hold the 'old'
+ * rq->lock and can modify state directly.
+ */
+ lockdep_assert_held(&task_rq(p)->lock);
+ detach_entity_cfs_rq(&p->se);
+
+ } else {
+ /*
+ * We are supposed to update the task to "current" time, then
+ * its up to date and ready to go to new CPU/cfs_rq. But we
+ * have difficulty in getting what current time is, so simply
+ * throw away the out-of-date time. This will result in the
+ * wakee task is less decayed, but giving the wakee more load
+ * sounds not bad.
+ */
+ remove_entity_load_avg(&p->se);
+ }
/* Tell new CPU we are migrated */
p->se.avg.last_update_time = 0;
@@ -6334,10 +6658,7 @@ again:
set_next_entity(cfs_rq, se);
}
- if (hrtick_enabled(rq))
- hrtick_start_fair(rq, p);
-
- return p;
+ goto done;
simple:
#endif
@@ -6351,6 +6672,16 @@ simple:
p = task_of(se);
+done: __maybe_unused
+#ifdef CONFIG_SMP
+ /*
+ * Move the next running task to the front of
+ * the list, so our cfs_tasks list becomes MRU
+ * one.
+ */
+ list_move(&p->se.group_node, &rq->cfs_tasks);
+#endif
+
if (hrtick_enabled(rq))
hrtick_start_fair(rq, p);
@@ -6786,11 +7117,12 @@ static void detach_task(struct task_struct *p, struct lb_env *env)
*/
static struct task_struct *detach_one_task(struct lb_env *env)
{
- struct task_struct *p, *n;
+ struct task_struct *p;
lockdep_assert_held(&env->src_rq->lock);
- list_for_each_entry_safe(p, n, &env->src_rq->cfs_tasks, se.group_node) {
+ list_for_each_entry_reverse(p,
+ &env->src_rq->cfs_tasks, se.group_node) {
if (!can_migrate_task(p, env))
continue;
@@ -6836,7 +7168,7 @@ static int detach_tasks(struct lb_env *env)
if (env->idle != CPU_NOT_IDLE && env->src_rq->nr_running <= 1)
break;
- p = list_first_entry(tasks, struct task_struct, se.group_node);
+ p = list_last_entry(tasks, struct task_struct, se.group_node);
env->loop++;
/* We've more or less seen every task there is, call it quits */
@@ -6886,7 +7218,7 @@ static int detach_tasks(struct lb_env *env)
continue;
next:
- list_move_tail(&p->se.group_node, tasks);
+ list_move(&p->se.group_node, tasks);
}
/*
@@ -6962,7 +7294,7 @@ static inline bool cfs_rq_is_decayed(struct cfs_rq *cfs_rq)
if (cfs_rq->avg.util_sum)
return false;
- if (cfs_rq->runnable_load_sum)
+ if (cfs_rq->avg.runnable_load_sum)
return false;
return true;
@@ -6994,7 +7326,7 @@ static void update_blocked_averages(int cpu)
/* Propagate pending load changes to the parent, if any: */
se = cfs_rq->tg->se[cpu];
if (se && !skip_blocked_update(se))
- update_load_avg(se, 0);
+ update_load_avg(cfs_rq_of(se), se, 0);
/*
* There can be a lot of idle CPU cgroups. Don't let fully
@@ -7875,8 +8207,11 @@ static struct sched_group *find_busiest_group(struct lb_env *env)
if (busiest->group_type == group_imbalanced)
goto force_balance;
- /* SD_BALANCE_NEWIDLE trumps SMP nice when underutilized */
- if (env->idle == CPU_NEWLY_IDLE && group_has_capacity(env, local) &&
+ /*
+ * When dst_cpu is idle, prevent SMP nice and/or asymmetric group
+ * capacities from resulting in underutilization due to avg_load.
+ */
+ if (env->idle != CPU_NOT_IDLE && group_has_capacity(env, local) &&
busiest->group_no_capacity)
goto force_balance;
@@ -8693,7 +9028,7 @@ void nohz_balance_enter_idle(int cpu)
return;
/* Spare idle load balancing on CPUs that don't want to be disturbed: */
- if (!is_housekeeping_cpu(cpu))
+ if (!housekeeping_cpu(cpu, HK_FLAG_SCHED))
return;
if (test_bit(NOHZ_TICK_STOPPED, nohz_flags(cpu)))
@@ -9158,7 +9493,7 @@ static void propagate_entity_cfs_rq(struct sched_entity *se)
if (cfs_rq_throttled(cfs_rq))
break;
- update_load_avg(se, UPDATE_TG);
+ update_load_avg(cfs_rq, se, UPDATE_TG);
}
}
#else
@@ -9170,7 +9505,7 @@ static void detach_entity_cfs_rq(struct sched_entity *se)
struct cfs_rq *cfs_rq = cfs_rq_of(se);
/* Catch up with the cfs_rq and remove our load when we leave */
- update_load_avg(se, 0);
+ update_load_avg(cfs_rq, se, 0);
detach_entity_load_avg(cfs_rq, se);
update_tg_load_avg(cfs_rq, false);
propagate_entity_cfs_rq(se);
@@ -9189,7 +9524,7 @@ static void attach_entity_cfs_rq(struct sched_entity *se)
#endif
/* Synchronize entity with its cfs_rq */
- update_load_avg(se, sched_feat(ATTACH_AGE_LOAD) ? 0 : SKIP_AGE_LOAD);
+ update_load_avg(cfs_rq, se, sched_feat(ATTACH_AGE_LOAD) ? 0 : SKIP_AGE_LOAD);
attach_entity_load_avg(cfs_rq, se);
update_tg_load_avg(cfs_rq, false);
propagate_entity_cfs_rq(se);
@@ -9271,11 +9606,7 @@ void init_cfs_rq(struct cfs_rq *cfs_rq)
cfs_rq->min_vruntime_copy = cfs_rq->min_vruntime;
#endif
#ifdef CONFIG_SMP
-#ifdef CONFIG_FAIR_GROUP_SCHED
- cfs_rq->propagate_avg = 0;
-#endif
- atomic_long_set(&cfs_rq->removed_load_avg, 0);
- atomic_long_set(&cfs_rq->removed_util_avg, 0);
+ raw_spin_lock_init(&cfs_rq->removed.lock);
#endif
}
@@ -9473,8 +9804,8 @@ int sched_group_set_shares(struct task_group *tg, unsigned long shares)
rq_lock_irqsave(rq, &rf);
update_rq_clock(rq);
for_each_sched_entity(se) {
- update_load_avg(se, UPDATE_TG);
- update_cfs_shares(se);
+ update_load_avg(cfs_rq_of(se), se, UPDATE_TG);
+ update_cfs_group(se);
}
rq_unlock_irqrestore(rq, &rf);
}
diff --git a/kernel/sched/idle.c b/kernel/sched/idle.c
index 257f4f0b4532..7dae9eb8c042 100644
--- a/kernel/sched/idle.c
+++ b/kernel/sched/idle.c
@@ -209,6 +209,7 @@ exit_idle:
*/
static void do_idle(void)
{
+ int cpu = smp_processor_id();
/*
* If the arch has a polling bit, we maintain an invariant:
*
@@ -219,14 +220,13 @@ static void do_idle(void)
*/
__current_set_polling();
- quiet_vmstat();
tick_nohz_idle_enter();
while (!need_resched()) {
check_pgt_cache();
rmb();
- if (cpu_is_offline(smp_processor_id())) {
+ if (cpu_is_offline(cpu)) {
cpuhp_report_idle_dead();
arch_cpu_idle_dead();
}
diff --git a/kernel/sched/isolation.c b/kernel/sched/isolation.c
new file mode 100644
index 000000000000..b71b436f59f2
--- /dev/null
+++ b/kernel/sched/isolation.c
@@ -0,0 +1,155 @@
+/*
+ * Housekeeping management. Manage the targets for routine code that can run on
+ * any CPU: unbound workqueues, timers, kthreads and any offloadable work.
+ *
+ * Copyright (C) 2017 Red Hat, Inc., Frederic Weisbecker
+ *
+ */
+
+#include <linux/sched/isolation.h>
+#include <linux/tick.h>
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/static_key.h>
+#include <linux/ctype.h>
+
+DEFINE_STATIC_KEY_FALSE(housekeeping_overriden);
+EXPORT_SYMBOL_GPL(housekeeping_overriden);
+static cpumask_var_t housekeeping_mask;
+static unsigned int housekeeping_flags;
+
+int housekeeping_any_cpu(enum hk_flags flags)
+{
+ if (static_branch_unlikely(&housekeeping_overriden))
+ if (housekeeping_flags & flags)
+ return cpumask_any_and(housekeeping_mask, cpu_online_mask);
+ return smp_processor_id();
+}
+EXPORT_SYMBOL_GPL(housekeeping_any_cpu);
+
+const struct cpumask *housekeeping_cpumask(enum hk_flags flags)
+{
+ if (static_branch_unlikely(&housekeeping_overriden))
+ if (housekeeping_flags & flags)
+ return housekeeping_mask;
+ return cpu_possible_mask;
+}
+EXPORT_SYMBOL_GPL(housekeeping_cpumask);
+
+void housekeeping_affine(struct task_struct *t, enum hk_flags flags)
+{
+ if (static_branch_unlikely(&housekeeping_overriden))
+ if (housekeeping_flags & flags)
+ set_cpus_allowed_ptr(t, housekeeping_mask);
+}
+EXPORT_SYMBOL_GPL(housekeeping_affine);
+
+bool housekeeping_test_cpu(int cpu, enum hk_flags flags)
+{
+ if (static_branch_unlikely(&housekeeping_overriden))
+ if (housekeeping_flags & flags)
+ return cpumask_test_cpu(cpu, housekeeping_mask);
+ return true;
+}
+EXPORT_SYMBOL_GPL(housekeeping_test_cpu);
+
+void __init housekeeping_init(void)
+{
+ if (!housekeeping_flags)
+ return;
+
+ static_branch_enable(&housekeeping_overriden);
+
+ /* We need at least one CPU to handle housekeeping work */
+ WARN_ON_ONCE(cpumask_empty(housekeeping_mask));
+}
+
+static int __init housekeeping_setup(char *str, enum hk_flags flags)
+{
+ cpumask_var_t non_housekeeping_mask;
+ int err;
+
+ alloc_bootmem_cpumask_var(&non_housekeeping_mask);
+ err = cpulist_parse(str, non_housekeeping_mask);
+ if (err < 0 || cpumask_last(non_housekeeping_mask) >= nr_cpu_ids) {
+ pr_warn("Housekeeping: nohz_full= or isolcpus= incorrect CPU range\n");
+ free_bootmem_cpumask_var(non_housekeeping_mask);
+ return 0;
+ }
+
+ if (!housekeeping_flags) {
+ alloc_bootmem_cpumask_var(&housekeeping_mask);
+ cpumask_andnot(housekeeping_mask,
+ cpu_possible_mask, non_housekeeping_mask);
+ if (cpumask_empty(housekeeping_mask))
+ cpumask_set_cpu(smp_processor_id(), housekeeping_mask);
+ } else {
+ cpumask_var_t tmp;
+
+ alloc_bootmem_cpumask_var(&tmp);
+ cpumask_andnot(tmp, cpu_possible_mask, non_housekeeping_mask);
+ if (!cpumask_equal(tmp, housekeeping_mask)) {
+ pr_warn("Housekeeping: nohz_full= must match isolcpus=\n");
+ free_bootmem_cpumask_var(tmp);
+ free_bootmem_cpumask_var(non_housekeeping_mask);
+ return 0;
+ }
+ free_bootmem_cpumask_var(tmp);
+ }
+
+ if ((flags & HK_FLAG_TICK) && !(housekeeping_flags & HK_FLAG_TICK)) {
+ if (IS_ENABLED(CONFIG_NO_HZ_FULL)) {
+ tick_nohz_full_setup(non_housekeeping_mask);
+ } else {
+ pr_warn("Housekeeping: nohz unsupported."
+ " Build with CONFIG_NO_HZ_FULL\n");
+ free_bootmem_cpumask_var(non_housekeeping_mask);
+ return 0;
+ }
+ }
+
+ housekeeping_flags |= flags;
+
+ free_bootmem_cpumask_var(non_housekeeping_mask);
+
+ return 1;
+}
+
+static int __init housekeeping_nohz_full_setup(char *str)
+{
+ unsigned int flags;
+
+ flags = HK_FLAG_TICK | HK_FLAG_TIMER | HK_FLAG_RCU | HK_FLAG_MISC;
+
+ return housekeeping_setup(str, flags);
+}
+__setup("nohz_full=", housekeeping_nohz_full_setup);
+
+static int __init housekeeping_isolcpus_setup(char *str)
+{
+ unsigned int flags = 0;
+
+ while (isalpha(*str)) {
+ if (!strncmp(str, "nohz,", 5)) {
+ str += 5;
+ flags |= HK_FLAG_TICK;
+ continue;
+ }
+
+ if (!strncmp(str, "domain,", 7)) {
+ str += 7;
+ flags |= HK_FLAG_DOMAIN;
+ continue;
+ }
+
+ pr_warn("isolcpus: Error, unknown flag\n");
+ return 0;
+ }
+
+ /* Default behaviour for isolcpus without flags */
+ if (!flags)
+ flags |= HK_FLAG_DOMAIN;
+
+ return housekeeping_setup(str, flags);
+}
+__setup("isolcpus=", housekeeping_isolcpus_setup);
diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c
index 3c96c80e0992..d8c43d73e078 100644
--- a/kernel/sched/rt.c
+++ b/kernel/sched/rt.c
@@ -74,10 +74,6 @@ static void start_rt_bandwidth(struct rt_bandwidth *rt_b)
raw_spin_unlock(&rt_b->rt_runtime_lock);
}
-#if defined(CONFIG_SMP) && defined(HAVE_RT_PUSH_IPI)
-static void push_irq_work_func(struct irq_work *work);
-#endif
-
void init_rt_rq(struct rt_rq *rt_rq)
{
struct rt_prio_array *array;
@@ -97,13 +93,6 @@ void init_rt_rq(struct rt_rq *rt_rq)
rt_rq->rt_nr_migratory = 0;
rt_rq->overloaded = 0;
plist_head_init(&rt_rq->pushable_tasks);
-
-#ifdef HAVE_RT_PUSH_IPI
- rt_rq->push_flags = 0;
- rt_rq->push_cpu = nr_cpu_ids;
- raw_spin_lock_init(&rt_rq->push_lock);
- init_irq_work(&rt_rq->push_work, push_irq_work_func);
-#endif
#endif /* CONFIG_SMP */
/* We start is dequeued state, because no RT tasks are queued */
rt_rq->rt_queued = 0;
@@ -1876,241 +1865,166 @@ static void push_rt_tasks(struct rq *rq)
}
#ifdef HAVE_RT_PUSH_IPI
+
/*
- * The search for the next cpu always starts at rq->cpu and ends
- * when we reach rq->cpu again. It will never return rq->cpu.
- * This returns the next cpu to check, or nr_cpu_ids if the loop
- * is complete.
+ * When a high priority task schedules out from a CPU and a lower priority
+ * task is scheduled in, a check is made to see if there's any RT tasks
+ * on other CPUs that are waiting to run because a higher priority RT task
+ * is currently running on its CPU. In this case, the CPU with multiple RT
+ * tasks queued on it (overloaded) needs to be notified that a CPU has opened
+ * up that may be able to run one of its non-running queued RT tasks.
+ *
+ * All CPUs with overloaded RT tasks need to be notified as there is currently
+ * no way to know which of these CPUs have the highest priority task waiting
+ * to run. Instead of trying to take a spinlock on each of these CPUs,
+ * which has shown to cause large latency when done on machines with many
+ * CPUs, sending an IPI to the CPUs to have them push off the overloaded
+ * RT tasks waiting to run.
+ *
+ * Just sending an IPI to each of the CPUs is also an issue, as on large
+ * count CPU machines, this can cause an IPI storm on a CPU, especially
+ * if its the only CPU with multiple RT tasks queued, and a large number
+ * of CPUs scheduling a lower priority task at the same time.
+ *
+ * Each root domain has its own irq work function that can iterate over
+ * all CPUs with RT overloaded tasks. Since all CPUs with overloaded RT
+ * tassk must be checked if there's one or many CPUs that are lowering
+ * their priority, there's a single irq work iterator that will try to
+ * push off RT tasks that are waiting to run.
+ *
+ * When a CPU schedules a lower priority task, it will kick off the
+ * irq work iterator that will jump to each CPU with overloaded RT tasks.
+ * As it only takes the first CPU that schedules a lower priority task
+ * to start the process, the rto_start variable is incremented and if
+ * the atomic result is one, then that CPU will try to take the rto_lock.
+ * This prevents high contention on the lock as the process handles all
+ * CPUs scheduling lower priority tasks.
+ *
+ * All CPUs that are scheduling a lower priority task will increment the
+ * rt_loop_next variable. This will make sure that the irq work iterator
+ * checks all RT overloaded CPUs whenever a CPU schedules a new lower
+ * priority task, even if the iterator is in the middle of a scan. Incrementing
+ * the rt_loop_next will cause the iterator to perform another scan.
*
- * rq->rt.push_cpu holds the last cpu returned by this function,
- * or if this is the first instance, it must hold rq->cpu.
*/
static int rto_next_cpu(struct rq *rq)
{
- int prev_cpu = rq->rt.push_cpu;
+ struct root_domain *rd = rq->rd;
+ int next;
int cpu;
- cpu = cpumask_next(prev_cpu, rq->rd->rto_mask);
-
/*
- * If the previous cpu is less than the rq's CPU, then it already
- * passed the end of the mask, and has started from the beginning.
- * We end if the next CPU is greater or equal to rq's CPU.
+ * When starting the IPI RT pushing, the rto_cpu is set to -1,
+ * rt_next_cpu() will simply return the first CPU found in
+ * the rto_mask.
+ *
+ * If rto_next_cpu() is called with rto_cpu is a valid cpu, it
+ * will return the next CPU found in the rto_mask.
+ *
+ * If there are no more CPUs left in the rto_mask, then a check is made
+ * against rto_loop and rto_loop_next. rto_loop is only updated with
+ * the rto_lock held, but any CPU may increment the rto_loop_next
+ * without any locking.
*/
- if (prev_cpu < rq->cpu) {
- if (cpu >= rq->cpu)
- return nr_cpu_ids;
+ for (;;) {
- } else if (cpu >= nr_cpu_ids) {
- /*
- * We passed the end of the mask, start at the beginning.
- * If the result is greater or equal to the rq's CPU, then
- * the loop is finished.
- */
- cpu = cpumask_first(rq->rd->rto_mask);
- if (cpu >= rq->cpu)
- return nr_cpu_ids;
- }
- rq->rt.push_cpu = cpu;
+ /* When rto_cpu is -1 this acts like cpumask_first() */
+ cpu = cpumask_next(rd->rto_cpu, rd->rto_mask);
- /* Return cpu to let the caller know if the loop is finished or not */
- return cpu;
-}
+ rd->rto_cpu = cpu;
-static int find_next_push_cpu(struct rq *rq)
-{
- struct rq *next_rq;
- int cpu;
+ if (cpu < nr_cpu_ids)
+ return cpu;
- while (1) {
- cpu = rto_next_cpu(rq);
- if (cpu >= nr_cpu_ids)
- break;
- next_rq = cpu_rq(cpu);
+ rd->rto_cpu = -1;
+
+ /*
+ * ACQUIRE ensures we see the @rto_mask changes
+ * made prior to the @next value observed.
+ *
+ * Matches WMB in rt_set_overload().
+ */
+ next = atomic_read_acquire(&rd->rto_loop_next);
- /* Make sure the next rq can push to this rq */
- if (next_rq->rt.highest_prio.next < rq->rt.highest_prio.curr)
+ if (rd->rto_loop == next)
break;
+
+ rd->rto_loop = next;
}
- return cpu;
+ return -1;
}
-#define RT_PUSH_IPI_EXECUTING 1
-#define RT_PUSH_IPI_RESTART 2
+static inline bool rto_start_trylock(atomic_t *v)
+{
+ return !atomic_cmpxchg_acquire(v, 0, 1);
+}
-/*
- * When a high priority task schedules out from a CPU and a lower priority
- * task is scheduled in, a check is made to see if there's any RT tasks
- * on other CPUs that are waiting to run because a higher priority RT task
- * is currently running on its CPU. In this case, the CPU with multiple RT
- * tasks queued on it (overloaded) needs to be notified that a CPU has opened
- * up that may be able to run one of its non-running queued RT tasks.
- *
- * On large CPU boxes, there's the case that several CPUs could schedule
- * a lower priority task at the same time, in which case it will look for
- * any overloaded CPUs that it could pull a task from. To do this, the runqueue
- * lock must be taken from that overloaded CPU. Having 10s of CPUs all fighting
- * for a single overloaded CPU's runqueue lock can produce a large latency.
- * (This has actually been observed on large boxes running cyclictest).
- * Instead of taking the runqueue lock of the overloaded CPU, each of the
- * CPUs that scheduled a lower priority task simply sends an IPI to the
- * overloaded CPU. An IPI is much cheaper than taking an runqueue lock with
- * lots of contention. The overloaded CPU will look to push its non-running
- * RT task off, and if it does, it can then ignore the other IPIs coming
- * in, and just pass those IPIs off to any other overloaded CPU.
- *
- * When a CPU schedules a lower priority task, it only sends an IPI to
- * the "next" CPU that has overloaded RT tasks. This prevents IPI storms,
- * as having 10 CPUs scheduling lower priority tasks and 10 CPUs with
- * RT overloaded tasks, would cause 100 IPIs to go out at once.
- *
- * The overloaded RT CPU, when receiving an IPI, will try to push off its
- * overloaded RT tasks and then send an IPI to the next CPU that has
- * overloaded RT tasks. This stops when all CPUs with overloaded RT tasks
- * have completed. Just because a CPU may have pushed off its own overloaded
- * RT task does not mean it should stop sending the IPI around to other
- * overloaded CPUs. There may be another RT task waiting to run on one of
- * those CPUs that are of higher priority than the one that was just
- * pushed.
- *
- * An optimization that could possibly be made is to make a CPU array similar
- * to the cpupri array mask of all running RT tasks, but for the overloaded
- * case, then the IPI could be sent to only the CPU with the highest priority
- * RT task waiting, and that CPU could send off further IPIs to the CPU with
- * the next highest waiting task. Since the overloaded case is much less likely
- * to happen, the complexity of this implementation may not be worth it.
- * Instead, just send an IPI around to all overloaded CPUs.
- *
- * The rq->rt.push_flags holds the status of the IPI that is going around.
- * A run queue can only send out a single IPI at a time. The possible flags
- * for rq->rt.push_flags are:
- *
- * (None or zero): No IPI is going around for the current rq
- * RT_PUSH_IPI_EXECUTING: An IPI for the rq is being passed around
- * RT_PUSH_IPI_RESTART: The priority of the running task for the rq
- * has changed, and the IPI should restart
- * circulating the overloaded CPUs again.
- *
- * rq->rt.push_cpu contains the CPU that is being sent the IPI. It is updated
- * before sending to the next CPU.
- *
- * Instead of having all CPUs that schedule a lower priority task send
- * an IPI to the same "first" CPU in the RT overload mask, they send it
- * to the next overloaded CPU after their own CPU. This helps distribute
- * the work when there's more than one overloaded CPU and multiple CPUs
- * scheduling in lower priority tasks.
- *
- * When a rq schedules a lower priority task than what was currently
- * running, the next CPU with overloaded RT tasks is examined first.
- * That is, if CPU 1 and 5 are overloaded, and CPU 3 schedules a lower
- * priority task, it will send an IPI first to CPU 5, then CPU 5 will
- * send to CPU 1 if it is still overloaded. CPU 1 will clear the
- * rq->rt.push_flags if RT_PUSH_IPI_RESTART is not set.
- *
- * The first CPU to notice IPI_RESTART is set, will clear that flag and then
- * send an IPI to the next overloaded CPU after the rq->cpu and not the next
- * CPU after push_cpu. That is, if CPU 1, 4 and 5 are overloaded when CPU 3
- * schedules a lower priority task, and the IPI_RESTART gets set while the
- * handling is being done on CPU 5, it will clear the flag and send it back to
- * CPU 4 instead of CPU 1.
- *
- * Note, the above logic can be disabled by turning off the sched_feature
- * RT_PUSH_IPI. Then the rq lock of the overloaded CPU will simply be
- * taken by the CPU requesting a pull and the waiting RT task will be pulled
- * by that CPU. This may be fine for machines with few CPUs.
- */
-static void tell_cpu_to_push(struct rq *rq)
+static inline void rto_start_unlock(atomic_t *v)
{
- int cpu;
+ atomic_set_release(v, 0);
+}
- if (rq->rt.push_flags & RT_PUSH_IPI_EXECUTING) {
- raw_spin_lock(&rq->rt.push_lock);
- /* Make sure it's still executing */
- if (rq->rt.push_flags & RT_PUSH_IPI_EXECUTING) {
- /*
- * Tell the IPI to restart the loop as things have
- * changed since it started.
- */
- rq->rt.push_flags |= RT_PUSH_IPI_RESTART;
- raw_spin_unlock(&rq->rt.push_lock);
- return;
- }
- raw_spin_unlock(&rq->rt.push_lock);
- }
+static void tell_cpu_to_push(struct rq *rq)
+{
+ int cpu = -1;
- /* When here, there's no IPI going around */
+ /* Keep the loop going if the IPI is currently active */
+ atomic_inc(&rq->rd->rto_loop_next);
- rq->rt.push_cpu = rq->cpu;
- cpu = find_next_push_cpu(rq);
- if (cpu >= nr_cpu_ids)
+ /* Only one CPU can initiate a loop at a time */
+ if (!rto_start_trylock(&rq->rd->rto_loop_start))
return;
- rq->rt.push_flags = RT_PUSH_IPI_EXECUTING;
+ raw_spin_lock(&rq->rd->rto_lock);
+
+ /*
+ * The rto_cpu is updated under the lock, if it has a valid cpu
+ * then the IPI is still running and will continue due to the
+ * update to loop_next, and nothing needs to be done here.
+ * Otherwise it is finishing up and an ipi needs to be sent.
+ */
+ if (rq->rd->rto_cpu < 0)
+ cpu = rto_next_cpu(rq);
- irq_work_queue_on(&rq->rt.push_work, cpu);
+ raw_spin_unlock(&rq->rd->rto_lock);
+
+ rto_start_unlock(&rq->rd->rto_loop_start);
+
+ if (cpu >= 0)
+ irq_work_queue_on(&rq->rd->rto_push_work, cpu);
}
/* Called from hardirq context */
-static void try_to_push_tasks(void *arg)
+void rto_push_irq_work_func(struct irq_work *work)
{
- struct rt_rq *rt_rq = arg;
- struct rq *rq, *src_rq;
- int this_cpu;
+ struct rq *rq;
int cpu;
- this_cpu = rt_rq->push_cpu;
+ rq = this_rq();
- /* Paranoid check */
- BUG_ON(this_cpu != smp_processor_id());
-
- rq = cpu_rq(this_cpu);
- src_rq = rq_of_rt_rq(rt_rq);
-
-again:
+ /*
+ * We do not need to grab the lock to check for has_pushable_tasks.
+ * When it gets updated, a check is made if a push is possible.
+ */
if (has_pushable_tasks(rq)) {
raw_spin_lock(&rq->lock);
- push_rt_task(rq);
+ push_rt_tasks(rq);
raw_spin_unlock(&rq->lock);
}
- /* Pass the IPI to the next rt overloaded queue */
- raw_spin_lock(&rt_rq->push_lock);
- /*
- * If the source queue changed since the IPI went out,
- * we need to restart the search from that CPU again.
- */
- if (rt_rq->push_flags & RT_PUSH_IPI_RESTART) {
- rt_rq->push_flags &= ~RT_PUSH_IPI_RESTART;
- rt_rq->push_cpu = src_rq->cpu;
- }
+ raw_spin_lock(&rq->rd->rto_lock);
- cpu = find_next_push_cpu(src_rq);
+ /* Pass the IPI to the next rt overloaded queue */
+ cpu = rto_next_cpu(rq);
- if (cpu >= nr_cpu_ids)
- rt_rq->push_flags &= ~RT_PUSH_IPI_EXECUTING;
- raw_spin_unlock(&rt_rq->push_lock);
+ raw_spin_unlock(&rq->rd->rto_lock);
- if (cpu >= nr_cpu_ids)
+ if (cpu < 0)
return;
- /*
- * It is possible that a restart caused this CPU to be
- * chosen again. Don't bother with an IPI, just see if we
- * have more to push.
- */
- if (unlikely(cpu == rq->cpu))
- goto again;
-
/* Try the next RT overloaded CPU */
- irq_work_queue_on(&rt_rq->push_work, cpu);
-}
-
-static void push_irq_work_func(struct irq_work *work)
-{
- struct rt_rq *rt_rq = container_of(work, struct rt_rq, push_work);
-
- try_to_push_tasks(rt_rq);
+ irq_work_queue_on(&rq->rd->rto_push_work, cpu);
}
#endif /* HAVE_RT_PUSH_IPI */
diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index 3b448ba82225..45ab0bf564e7 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -227,7 +227,7 @@ struct dl_bw {
static inline void __dl_update(struct dl_bw *dl_b, s64 bw);
static inline
-void __dl_clear(struct dl_bw *dl_b, u64 tsk_bw, int cpus)
+void __dl_sub(struct dl_bw *dl_b, u64 tsk_bw, int cpus)
{
dl_b->total_bw -= tsk_bw;
__dl_update(dl_b, (s32)tsk_bw / cpus);
@@ -256,7 +256,6 @@ extern int sched_dl_overflow(struct task_struct *p, int policy,
extern void __setparam_dl(struct task_struct *p, const struct sched_attr *attr);
extern void __getparam_dl(struct task_struct *p, struct sched_attr *attr);
extern bool __checkparam_dl(const struct sched_attr *attr);
-extern void __dl_clear_params(struct task_struct *p);
extern bool dl_param_changed(struct task_struct *p, const struct sched_attr *attr);
extern int dl_task_can_attach(struct task_struct *p,
const struct cpumask *cs_cpus_allowed);
@@ -419,6 +418,7 @@ struct cfs_bandwidth { };
/* CFS-related fields in a runqueue */
struct cfs_rq {
struct load_weight load;
+ unsigned long runnable_weight;
unsigned int nr_running, h_nr_running;
u64 exec_clock;
@@ -444,18 +444,22 @@ struct cfs_rq {
* CFS load tracking
*/
struct sched_avg avg;
- u64 runnable_load_sum;
- unsigned long runnable_load_avg;
-#ifdef CONFIG_FAIR_GROUP_SCHED
- unsigned long tg_load_avg_contrib;
- unsigned long propagate_avg;
-#endif
- atomic_long_t removed_load_avg, removed_util_avg;
#ifndef CONFIG_64BIT
u64 load_last_update_time_copy;
#endif
+ struct {
+ raw_spinlock_t lock ____cacheline_aligned;
+ int nr;
+ unsigned long load_avg;
+ unsigned long util_avg;
+ unsigned long runnable_sum;
+ } removed;
#ifdef CONFIG_FAIR_GROUP_SCHED
+ unsigned long tg_load_avg_contrib;
+ long propagate;
+ long prop_runnable_sum;
+
/*
* h_load = weight * f(tg)
*
@@ -502,7 +506,7 @@ static inline int rt_bandwidth_enabled(void)
}
/* RT IPI pull logic requires IRQ_WORK */
-#ifdef CONFIG_IRQ_WORK
+#if defined(CONFIG_IRQ_WORK) && defined(CONFIG_SMP)
# define HAVE_RT_PUSH_IPI
#endif
@@ -524,12 +528,6 @@ struct rt_rq {
unsigned long rt_nr_total;
int overloaded;
struct plist_head pushable_tasks;
-#ifdef HAVE_RT_PUSH_IPI
- int push_flags;
- int push_cpu;
- struct irq_work push_work;
- raw_spinlock_t push_lock;
-#endif
#endif /* CONFIG_SMP */
int rt_queued;
@@ -638,6 +636,19 @@ struct root_domain {
struct dl_bw dl_bw;
struct cpudl cpudl;
+#ifdef HAVE_RT_PUSH_IPI
+ /*
+ * For IPI pull requests, loop across the rto_mask.
+ */
+ struct irq_work rto_push_work;
+ raw_spinlock_t rto_lock;
+ /* These are only updated and read within rto_lock */
+ int rto_loop;
+ int rto_cpu;
+ /* These atomics are updated outside of a lock */
+ atomic_t rto_loop_next;
+ atomic_t rto_loop_start;
+#endif
/*
* The "RT overload" flag: it gets set if a CPU has more than
* one runnable RT task.
@@ -655,6 +666,9 @@ extern void init_defrootdomain(void);
extern int sched_init_domains(const struct cpumask *cpu_map);
extern void rq_attach_root(struct rq *rq, struct root_domain *rd);
+#ifdef HAVE_RT_PUSH_IPI
+extern void rto_push_irq_work_func(struct irq_work *work);
+#endif
#endif /* CONFIG_SMP */
/*
@@ -1219,8 +1233,6 @@ static inline void __set_task_cpu(struct task_struct *p, unsigned int cpu)
# define const_debug const
#endif
-extern const_debug unsigned int sysctl_sched_features;
-
#define SCHED_FEAT(name, enabled) \
__SCHED_FEAT_##name ,
@@ -1232,6 +1244,13 @@ enum {
#undef SCHED_FEAT
#if defined(CONFIG_SCHED_DEBUG) && defined(HAVE_JUMP_LABEL)
+
+/*
+ * To support run-time toggling of sched features, all the translation units
+ * (but core.c) reference the sysctl_sched_features defined in core.c.
+ */
+extern const_debug unsigned int sysctl_sched_features;
+
#define SCHED_FEAT(name, enabled) \
static __always_inline bool static_branch_##name(struct static_key *key) \
{ \
@@ -1239,13 +1258,27 @@ static __always_inline bool static_branch_##name(struct static_key *key) \
}
#include "features.h"
-
#undef SCHED_FEAT
extern struct static_key sched_feat_keys[__SCHED_FEAT_NR];
#define sched_feat(x) (static_branch_##x(&sched_feat_keys[__SCHED_FEAT_##x]))
+
#else /* !(SCHED_DEBUG && HAVE_JUMP_LABEL) */
+
+/*
+ * Each translation unit has its own copy of sysctl_sched_features to allow
+ * constants propagation at compile time and compiler optimization based on
+ * features default.
+ */
+#define SCHED_FEAT(name, enabled) \
+ (1UL << __SCHED_FEAT_##name) * enabled |
+static const_debug __maybe_unused unsigned int sysctl_sched_features =
+#include "features.h"
+ 0;
+#undef SCHED_FEAT
+
#define sched_feat(x) (sysctl_sched_features & (1UL << __SCHED_FEAT_##x))
+
#endif /* SCHED_DEBUG && HAVE_JUMP_LABEL */
extern struct static_key_false sched_numa_balancing;
@@ -1530,6 +1563,8 @@ extern void init_sched_dl_class(void);
extern void init_sched_rt_class(void);
extern void init_sched_fair_class(void);
+extern void reweight_task(struct task_struct *p, int prio);
+
extern void resched_curr(struct rq *rq);
extern void resched_cpu(int cpu);
diff --git a/kernel/sched/topology.c b/kernel/sched/topology.c
index 6798276d29af..034cbed7f88b 100644
--- a/kernel/sched/topology.c
+++ b/kernel/sched/topology.c
@@ -4,6 +4,7 @@
*/
#include <linux/sched.h>
#include <linux/mutex.h>
+#include <linux/sched/isolation.h>
#include "sched.h"
@@ -269,6 +270,12 @@ static int init_rootdomain(struct root_domain *rd)
if (!zalloc_cpumask_var(&rd->rto_mask, GFP_KERNEL))
goto free_dlo_mask;
+#ifdef HAVE_RT_PUSH_IPI
+ rd->rto_cpu = -1;
+ raw_spin_lock_init(&rd->rto_lock);
+ init_irq_work(&rd->rto_push_work, rto_push_irq_work_func);
+#endif
+
init_dl_bw(&rd->dl_bw);
if (cpudl_init(&rd->cpudl) != 0)
goto free_rto_mask;
@@ -464,21 +471,6 @@ cpu_attach_domain(struct sched_domain *sd, struct root_domain *rd, int cpu)
update_top_cache_domain(cpu);
}
-/* Setup the mask of CPUs configured for isolated domains */
-static int __init isolated_cpu_setup(char *str)
-{
- int ret;
-
- alloc_bootmem_cpumask_var(&cpu_isolated_map);
- ret = cpulist_parse(str, cpu_isolated_map);
- if (ret) {
- pr_err("sched: Error, all isolcpus= values must be between 0 and %u\n", nr_cpu_ids);
- return 0;
- }
- return 1;
-}
-__setup("isolcpus=", isolated_cpu_setup);
-
struct s_data {
struct sched_domain ** __percpu sd;
struct root_domain *rd;
@@ -1158,6 +1150,7 @@ sd_init(struct sched_domain_topology_level *tl,
sd->smt_gain = 1178; /* ~15% */
} else if (sd->flags & SD_SHARE_PKG_RESOURCES) {
+ sd->flags |= SD_PREFER_SIBLING;
sd->imbalance_pct = 117;
sd->cache_nice_tries = 1;
sd->busy_idx = 2;
@@ -1332,6 +1325,10 @@ void sched_init_numa(void)
if (!sched_domains_numa_distance)
return;
+ /* Includes NUMA identity node at level 0. */
+ sched_domains_numa_distance[level++] = curr_distance;
+ sched_domains_numa_levels = level;
+
/*
* O(nr_nodes^2) deduplicating selection sort -- in order to find the
* unique distances in the node_distance() table.
@@ -1379,8 +1376,7 @@ void sched_init_numa(void)
return;
/*
- * 'level' contains the number of unique distances, excluding the
- * identity distance node_distance(i,i).
+ * 'level' contains the number of unique distances
*
* The sched_domains_numa_distance[] array includes the actual distance
* numbers.
@@ -1442,9 +1438,18 @@ void sched_init_numa(void)
tl[i] = sched_domain_topology[i];
/*
+ * Add the NUMA identity distance, aka single NODE.
+ */
+ tl[i++] = (struct sched_domain_topology_level){
+ .mask = sd_numa_mask,
+ .numa_level = 0,
+ SD_INIT_NAME(NODE)
+ };
+
+ /*
* .. and append 'j' levels of NUMA goodness.
*/
- for (j = 0; j < level; i++, j++) {
+ for (j = 1; j < level; i++, j++) {
tl[i] = (struct sched_domain_topology_level){
.mask = sd_numa_mask,
.sd_flags = cpu_numa_flags,
@@ -1774,7 +1779,7 @@ int sched_init_domains(const struct cpumask *cpu_map)
doms_cur = alloc_sched_domains(ndoms_cur);
if (!doms_cur)
doms_cur = &fallback_doms;
- cpumask_andnot(doms_cur[0], cpu_map, cpu_isolated_map);
+ cpumask_and(doms_cur[0], cpu_map, housekeeping_cpumask(HK_FLAG_DOMAIN));
err = build_sched_domains(doms_cur[0], NULL);
register_sched_domain_sysctl();
@@ -1857,7 +1862,8 @@ void partition_sched_domains(int ndoms_new, cpumask_var_t doms_new[],
doms_new = alloc_sched_domains(1);
if (doms_new) {
n = 1;
- cpumask_andnot(doms_new[0], cpu_active_mask, cpu_isolated_map);
+ cpumask_and(doms_new[0], cpu_active_mask,
+ housekeeping_cpumask(HK_FLAG_DOMAIN));
}
} else {
n = ndoms_new;
@@ -1880,7 +1886,8 @@ match1:
if (!doms_new) {
n = 0;
doms_new = &fallback_doms;
- cpumask_andnot(doms_new[0], cpu_active_mask, cpu_isolated_map);
+ cpumask_and(doms_new[0], cpu_active_mask,
+ housekeeping_cpumask(HK_FLAG_DOMAIN));
}
/* Build new domains: */
diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c
index dd4b7b492c9b..99578f06c8d4 100644
--- a/kernel/time/tick-sched.c
+++ b/kernel/time/tick-sched.c
@@ -27,6 +27,7 @@
#include <linux/irq_work.h>
#include <linux/posix-timers.h>
#include <linux/context_tracking.h>
+#include <linux/mm.h>
#include <asm/irq_regs.h>
@@ -165,7 +166,6 @@ static void tick_sched_handle(struct tick_sched *ts, struct pt_regs *regs)
#ifdef CONFIG_NO_HZ_FULL
cpumask_var_t tick_nohz_full_mask;
-cpumask_var_t housekeeping_mask;
bool tick_nohz_full_running;
static atomic_t tick_dep_mask;
@@ -385,20 +385,13 @@ out:
local_irq_restore(flags);
}
-/* Parse the boot-time nohz CPU list from the kernel parameters. */
-static int __init tick_nohz_full_setup(char *str)
+/* Get the boot-time nohz CPU list from the kernel parameters. */
+void __init tick_nohz_full_setup(cpumask_var_t cpumask)
{
alloc_bootmem_cpumask_var(&tick_nohz_full_mask);
- if (cpulist_parse(str, tick_nohz_full_mask) < 0) {
- pr_warn("NO_HZ: Incorrect nohz_full cpumask\n");
- free_bootmem_cpumask_var(tick_nohz_full_mask);
- return 1;
- }
+ cpumask_copy(tick_nohz_full_mask, cpumask);
tick_nohz_full_running = true;
-
- return 1;
}
-__setup("nohz_full=", tick_nohz_full_setup);
static int tick_nohz_cpu_down(unsigned int cpu)
{
@@ -437,13 +430,6 @@ void __init tick_nohz_init(void)
return;
}
- if (!alloc_cpumask_var(&housekeeping_mask, GFP_KERNEL)) {
- WARN(1, "NO_HZ: Can't allocate not-full dynticks cpumask\n");
- cpumask_clear(tick_nohz_full_mask);
- tick_nohz_full_running = false;
- return;
- }
-
/*
* Full dynticks uses irq work to drive the tick rescheduling on safe
* locking contexts. But then we need irq work to raise its own
@@ -452,7 +438,6 @@ void __init tick_nohz_init(void)
if (!arch_irq_work_has_interrupt()) {
pr_warn("NO_HZ: Can't run full dynticks because arch doesn't support irq work self-IPIs\n");
cpumask_clear(tick_nohz_full_mask);
- cpumask_copy(housekeeping_mask, cpu_possible_mask);
tick_nohz_full_running = false;
return;
}
@@ -465,9 +450,6 @@ void __init tick_nohz_init(void)
cpumask_clear_cpu(cpu, tick_nohz_full_mask);
}
- cpumask_andnot(housekeeping_mask,
- cpu_possible_mask, tick_nohz_full_mask);
-
for_each_cpu(cpu, tick_nohz_full_mask)
context_tracking_cpu_set(cpu);
@@ -477,12 +459,6 @@ void __init tick_nohz_init(void)
WARN_ON(ret < 0);
pr_info("NO_HZ: Full dynticks CPUs: %*pbl.\n",
cpumask_pr_args(tick_nohz_full_mask));
-
- /*
- * We need at least one CPU to handle housekeeping work such
- * as timekeeping, unbound timers, workqueues, ...
- */
- WARN_ON_ONCE(cpumask_empty(housekeeping_mask));
}
#endif
@@ -787,6 +763,7 @@ static ktime_t tick_nohz_stop_sched_tick(struct tick_sched *ts,
if (!ts->tick_stopped) {
calc_load_nohz_start();
cpu_load_update_nohz_start();
+ quiet_vmstat();
ts->last_tick = hrtimer_get_expires(&ts->sched_timer);
ts->tick_stopped = 1;
diff --git a/kernel/trace/trace_output.c b/kernel/trace/trace_output.c
index c738e764e2a5..90db994ac900 100644
--- a/kernel/trace/trace_output.c
+++ b/kernel/trace/trace_output.c
@@ -921,8 +921,8 @@ static enum print_line_t trace_ctxwake_print(struct trace_iterator *iter,
trace_assign_type(field, iter->ent);
- T = __task_state_to_char(field->next_state);
- S = __task_state_to_char(field->prev_state);
+ T = task_index_to_char(field->next_state);
+ S = task_index_to_char(field->prev_state);
trace_find_cmdline(field->next_pid, comm);
trace_seq_printf(&iter->seq,
" %5d:%3d:%c %s [%03d] %5d:%3d:%c %s\n",
@@ -957,8 +957,8 @@ static int trace_ctxwake_raw(struct trace_iterator *iter, char S)
trace_assign_type(field, iter->ent);
if (!S)
- S = __task_state_to_char(field->prev_state);
- T = __task_state_to_char(field->next_state);
+ S = task_index_to_char(field->prev_state);
+ T = task_index_to_char(field->next_state);
trace_seq_printf(&iter->seq, "%d %d %c %d %d %d %c\n",
field->prev_pid,
field->prev_prio,
@@ -993,8 +993,8 @@ static int trace_ctxwake_hex(struct trace_iterator *iter, char S)
trace_assign_type(field, iter->ent);
if (!S)
- S = __task_state_to_char(field->prev_state);
- T = __task_state_to_char(field->next_state);
+ S = task_index_to_char(field->prev_state);
+ T = task_index_to_char(field->next_state);
SEQ_PUT_HEX_FIELD(s, field->prev_pid);
SEQ_PUT_HEX_FIELD(s, field->prev_prio);
diff --git a/kernel/trace/trace_sched_wakeup.c b/kernel/trace/trace_sched_wakeup.c
index 7d461dcd4831..a86b303e6c67 100644
--- a/kernel/trace/trace_sched_wakeup.c
+++ b/kernel/trace/trace_sched_wakeup.c
@@ -398,10 +398,10 @@ tracing_sched_switch_trace(struct trace_array *tr,
entry = ring_buffer_event_data(event);
entry->prev_pid = prev->pid;
entry->prev_prio = prev->prio;
- entry->prev_state = __get_task_state(prev);
+ entry->prev_state = task_state_index(prev);
entry->next_pid = next->pid;
entry->next_prio = next->prio;
- entry->next_state = __get_task_state(next);
+ entry->next_state = task_state_index(next);
entry->next_cpu = task_cpu(next);
if (!call_filter_check_discard(call, entry, buffer, event))
@@ -426,10 +426,10 @@ tracing_sched_wakeup_trace(struct trace_array *tr,
entry = ring_buffer_event_data(event);
entry->prev_pid = curr->pid;
entry->prev_prio = curr->prio;
- entry->prev_state = __get_task_state(curr);
+ entry->prev_state = task_state_index(curr);
entry->next_pid = wakee->pid;
entry->next_prio = wakee->prio;
- entry->next_state = __get_task_state(wakee);
+ entry->next_state = task_state_index(wakee);
entry->next_cpu = task_cpu(wakee);
if (!call_filter_check_discard(call, entry, buffer, event))
diff --git a/kernel/watchdog.c b/kernel/watchdog.c
index c8e06703e44c..576d18045811 100644
--- a/kernel/watchdog.c
+++ b/kernel/watchdog.c
@@ -25,6 +25,7 @@
#include <linux/workqueue.h>
#include <linux/sched/clock.h>
#include <linux/sched/debug.h>
+#include <linux/sched/isolation.h>
#include <asm/irq_regs.h>
#include <linux/kvm_para.h>
@@ -774,15 +775,11 @@ int proc_watchdog_cpumask(struct ctl_table *table, int write,
void __init lockup_detector_init(void)
{
-#ifdef CONFIG_NO_HZ_FULL
- if (tick_nohz_full_enabled()) {
+ if (tick_nohz_full_enabled())
pr_info("Disabling watchdog on nohz_full cores by default\n");
- cpumask_copy(&watchdog_cpumask, housekeeping_mask);
- } else
- cpumask_copy(&watchdog_cpumask, cpu_possible_mask);
-#else
- cpumask_copy(&watchdog_cpumask, cpu_possible_mask);
-#endif
+
+ cpumask_copy(&watchdog_cpumask,
+ housekeeping_cpumask(HK_FLAG_TIMER));
if (!watchdog_nmi_probe())
nmi_watchdog_available = true;