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authorLinus Torvalds <torvalds@linux-foundation.org>2014-04-01 10:16:10 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2014-04-01 10:16:10 -0700
commita21e40877ad130de837b0394583e4f68dc2ab6c5 (patch)
treec990fba6ef5f2ed464c906615c5c327f2d02b318 /kernel
parentb9b16a792241e304834f43e2a5f02e6e43576f09 (diff)
parent073d8224d299528778e90773becd1e890953443c (diff)
downloadlinux-a21e40877ad130de837b0394583e4f68dc2ab6c5.tar.gz
Merge branch 'timers-nohz-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull timer updates from Ingo Molnar: "The main purpose is to fix a full dynticks bug related to virtualization, where steal time accounting appears to be zero in /proc/stat even after a few seconds of competing guests running busy loops in a same host CPU. It's not a regression though as it was there since the beginning. The other commits are preparatory work to fix the bug and various cleanups" * 'timers-nohz-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: arch: Remove stub cputime.h headers sched: Remove needless round trip nsecs <-> tick conversion of steal time cputime: Fix jiffies based cputime assumption on steal accounting cputime: Bring cputime -> nsecs conversion cputime: Default implementation of nsecs -> cputime conversion cputime: Fix nsecs_to_cputime() return type cast
Diffstat (limited to 'kernel')
-rw-r--r--kernel/sched/core.c6
-rw-r--r--kernel/sched/cputime.c16
-rw-r--r--kernel/sched/sched.h10
3 files changed, 11 insertions, 21 deletions
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index a47902c687a..d11a1768357 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -823,19 +823,13 @@ static void update_rq_clock_task(struct rq *rq, s64 delta)
#endif
#ifdef CONFIG_PARAVIRT_TIME_ACCOUNTING
if (static_key_false((&paravirt_steal_rq_enabled))) {
- u64 st;
-
steal = paravirt_steal_clock(cpu_of(rq));
steal -= rq->prev_steal_time_rq;
if (unlikely(steal > delta))
steal = delta;
- st = steal_ticks(steal);
- steal = st * TICK_NSEC;
-
rq->prev_steal_time_rq += steal;
-
delta -= steal;
}
#endif
diff --git a/kernel/sched/cputime.c b/kernel/sched/cputime.c
index 58624a65f12..a95097cb459 100644
--- a/kernel/sched/cputime.c
+++ b/kernel/sched/cputime.c
@@ -258,16 +258,22 @@ static __always_inline bool steal_account_process_tick(void)
{
#ifdef CONFIG_PARAVIRT
if (static_key_false(&paravirt_steal_enabled)) {
- u64 steal, st = 0;
+ u64 steal;
+ cputime_t steal_ct;
steal = paravirt_steal_clock(smp_processor_id());
steal -= this_rq()->prev_steal_time;
- st = steal_ticks(steal);
- this_rq()->prev_steal_time += st * TICK_NSEC;
+ /*
+ * cputime_t may be less precise than nsecs (eg: if it's
+ * based on jiffies). Lets cast the result to cputime
+ * granularity and account the rest on the next rounds.
+ */
+ steal_ct = nsecs_to_cputime(steal);
+ this_rq()->prev_steal_time += cputime_to_nsecs(steal_ct);
- account_steal_time(st);
- return st;
+ account_steal_time(steal_ct);
+ return steal_ct;
}
#endif
return false;
diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index f2de7a17562..c9007f28d3a 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -1216,16 +1216,6 @@ extern void update_idle_cpu_load(struct rq *this_rq);
extern void init_task_runnable_average(struct task_struct *p);
-#ifdef CONFIG_PARAVIRT
-static inline u64 steal_ticks(u64 steal)
-{
- if (unlikely(steal > NSEC_PER_SEC))
- return div_u64(steal, TICK_NSEC);
-
- return __iter_div_u64_rem(steal, TICK_NSEC, &steal);
-}
-#endif
-
static inline void inc_nr_running(struct rq *rq)
{
rq->nr_running++;