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authorMorten Rasmussen <Morten.Rasmussen@arm.com>2012-09-14 14:38:11 +0100
committerViresh Kumar <viresh.kumar@linaro.org>2013-03-12 14:54:32 +0530
commitb46f8c8b364e03ea97e0807fe4e09d32c9dce69a (patch)
tree342b89b464d5676f4dee0fd3305396a4ee787810
parentbc4ed1b52249e43657b264dcf8e12384d4d33b4c (diff)
downloadvexpress-lsk-b46f8c8b364e03ea97e0807fe4e09d32c9dce69a.tar.gz
sched: Introduce priority-based task migration filter
Introduces a priority threshold which prevents low priority task from migrating to faster hmp_domains (cpus). This is useful for user-space software which assigns lower task priority to background task. Signed-off-by: Morten Rasmussen <Morten.Rasmussen@arm.com>
-rw-r--r--arch/arm/Kconfig13
-rw-r--r--kernel/sched/fair.c17
2 files changed, 30 insertions, 0 deletions
diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index 7abe7094def..d24768c04be 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -1599,6 +1599,19 @@ config SCHED_HMP
!SCHED_AUTOGROUP. Furthermore, normal load-balancing must be disabled
between cpus of different type (DISABLE_CPU_SCHED_DOMAIN_BALANCE).
+config SCHED_HMP_PRIO_FILTER
+ bool "(EXPERIMENTAL) Filter HMP migrations by task priority"
+ depends on SCHED_HMP
+ help
+ Enables task priority based HMP migration filter. Any task with
+ a NICE value above the threshold will always be on low-power cpus
+ with less compute capacity.
+
+config SCHED_HMP_PRIO_FILTER_VAL
+ int "NICE priority threshold"
+ default 5
+ depends on SCHED_HMP_PRIO_FILTER
+
config HAVE_ARM_SCU
bool
help
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 44891b55ce1..715ac8b4f4b 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -3370,9 +3370,14 @@ static int __init hmp_cpu_mask_setup(void)
* hmp_down_threshold: max. load allowed for tasks migrating to a slower cpu
* The default values (512, 256) offer good responsiveness, but may need
* tweaking suit particular needs.
+ *
+ * hmp_up_prio: Only up migrate task with high priority (<hmp_up_prio)
*/
unsigned int hmp_up_threshold = 512;
unsigned int hmp_down_threshold = 256;
+#ifdef CONFIG_SCHED_HMP_PRIO_FILTER
+unsigned int hmp_up_prio = NICE_TO_PRIO(CONFIG_SCHED_HMP_PRIO_FILTER_VAL);
+#endif
static unsigned int hmp_up_migration(int cpu, struct sched_entity *se);
static unsigned int hmp_down_migration(int cpu, struct sched_entity *se);
@@ -5813,6 +5818,12 @@ static unsigned int hmp_up_migration(int cpu, struct sched_entity *se)
if (hmp_cpu_is_fastest(cpu))
return 0;
+#ifdef CONFIG_SCHED_HMP_PRIO_FILTER
+ /* Filter by task priority */
+ if (p->prio >= hmp_up_prio)
+ return 0;
+#endif
+
if (cpumask_intersects(&hmp_faster_domain(cpu)->cpus,
tsk_cpus_allowed(p))
&& se->avg.load_avg_ratio > hmp_up_threshold) {
@@ -5829,6 +5840,12 @@ static unsigned int hmp_down_migration(int cpu, struct sched_entity *se)
if (hmp_cpu_is_slowest(cpu))
return 0;
+#ifdef CONFIG_SCHED_HMP_PRIO_FILTER
+ /* Filter by task priority */
+ if (p->prio >= hmp_up_prio)
+ return 1;
+#endif
+
if (cpumask_intersects(&hmp_slower_domain(cpu)->cpus,
tsk_cpus_allowed(p))
&& se->avg.load_avg_ratio < hmp_down_threshold) {