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cpufreq: sched: update capacity request upon tick always

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At present, sched_freq_tick() skips updating of capacity update when
current frequency is fmax.  This can cause incorrect frequency drop
when a CPU bound task goes into sleep for example :
  1) A task (A) enqueues onto CPU 0 and executes for long time.
  2) A new task (B) which has low task demand enqueues onto CPU 1 and
     executes long so becomes a CPU bound task.
  3) Both CPU 0 and 1 gets scheduler tick but skip sched_freq_tick()
     since current frequency is fmax.
  4) Task (A) sleeps and lower the CPU 0's capacity request.
  5) Because task (B) voted CPU capacity at step 2 with low demand and
     skipped to request afterwards, cluster frequency for both CPU 0
     and 1 drops to match capacity voted by CPU 1 at step 2 even though
     task (B) on CPU 1 requires max capacity.

Fix such incorrectness by not skipping CPU capacity voting at tick
path.

Change-Id: Ieb46af1ac96ffce7a5532c58c7f07bf1ada06b86
Signed-off-by: Joonwoo Park <joonwoop@codeaurora.org>
Signed-off-by: Vikram Mulukutla <markivx@codeaurora.org>
This commit is contained in:
Joonwoo Park 2016-12-20 15:23:53 -08:00 committed by Amit Pundir
parent 2067342dbc
commit 4ffc773858
1 changed files with 0 additions and 7 deletions
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7
kernel/sched/core.c
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@ -3025,16 +3025,9 @@ static void sched_freq_tick_walt(int cpu)
static void sched_freq_tick(int cpu)
{
unsigned long capacity_orig, capacity_curr;
if (!sched_freq())
return;
capacity_orig = capacity_orig_of(cpu);
capacity_curr = capacity_curr_of(cpu);
if (capacity_curr == capacity_orig)
return;
_sched_freq_tick(cpu);
}
#else