Files
linux/kernel
Joonwoo Park 4ffc773858 cpufreq: sched: update capacity request upon tick always
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>
2017-11-20 21:15:59 +05:30
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