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sched: Add struct rq::cpu_capacity_orig

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This new field 'cpu_capacity_orig' reflects the original capacity of a CPU
before being altered by rt tasks and/or IRQ

The cpu_capacity_orig will be used:

  - to detect when the capacity of a CPU has been noticeably reduced so we can
    trig load balance to look for a CPU with better capacity. As an example, we
    can detect when a CPU handles a significant amount of irq
    (with CONFIG_IRQ_TIME_ACCOUNTING) but this CPU is seen as an idle CPU by
    scheduler whereas CPUs, which are really idle, are available.

  - evaluate the available capacity for CFS tasks

Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Kamalesh Babulal <kamalesh@linux.vnet.ibm.com>
Acked-by: Morten Rasmussen <morten.rasmussen@arm.com>
Cc: Morten.Rasmussen@arm.com
Cc: dietmar.eggemann@arm.com
Cc: efault@gmx.de
Cc: linaro-kernel@lists.linaro.org
Cc: nicolas.pitre@linaro.org
Cc: preeti@linux.vnet.ibm.com
Cc: riel@redhat.com
Link: http://lkml.kernel.org/r/1425052454-25797-7-git-send-email-vincent.guittot@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Vincent Guittot
2015-02-27 16:54:09 +01:00
committed by Ingo Molnar
parent b5b4860d1d
commit ca6d75e690
3 changed files with 9 additions and 2 deletions
Download Patch File Download Diff File Expand all files Collapse all files
kernel/sched/fair.c
+7 -1
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@@ -4363,6 +4363,11 @@ static unsigned long capacity_of(int cpu)
return cpu_rq(cpu)->cpu_capacity;
}
static unsigned long capacity_orig_of(int cpu)
{
return cpu_rq(cpu)->cpu_capacity_orig;
}
static unsigned long cpu_avg_load_per_task(int cpu)
{
struct rq *rq = cpu_rq(cpu);
@@ -6040,6 +6045,7 @@ static void update_cpu_capacity(struct sched_domain *sd, int cpu)
capacity >>= SCHED_CAPACITY_SHIFT;
cpu_rq(cpu)->cpu_capacity_orig = capacity;
sdg->sgc->capacity_orig = capacity;
capacity *= scale_rt_capacity(cpu);
@@ -6094,7 +6100,7 @@ void update_group_capacity(struct sched_domain *sd, int cpu)
* Runtime updates will correct capacity_orig.
*/
if (unlikely(!rq->sd)) {
capacity_orig += capacity_of(cpu);
capacity_orig += capacity_orig_of(cpu);
capacity += capacity_of(cpu);
continue;
}