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| author | Pavankumar Kondeti <pkondeti@codeaurora.org> | 2016-09-06 11:59:28 +0530 |
|---|---|---|
| committer | Pavankumar Kondeti <pkondeti@codeaurora.org> | 2016-10-02 10:52:06 +0530 |
| commit | f1e9995fe4f21c491e71716e3bc4027fd14954e8 (patch) | |
| tree | 2c581a8bbc53a697ac949e9fc27ff9983129ca54 /Documentation/scheduler | |
| parent | 46692be6dd06ce405cb09cf8338b1f0edbbfb295 (diff) | |
sched: add a knob to prefer the waker CPU for sync wakeups
The current policy has a preference to select an idle CPU in the waker
cluster compared to the waker CPU running only 1 task. By selecting
an idle CPU, it eliminates the chance of waker migrating to a
different CPU after the wakee preempts it. This policy is also not
susceptible to the incorrect "sync" usage i.e the waker does not
goto sleep after waking up the wakee.
However LPM exit latency associated with an idle CPU outweigh the
above benefits on some targets. So add a knob to prefer the waker
CPU having only 1 runnable task over idle CPUs in the waker cluster.
Change-Id: Id974748c07625c1b19112235f426a5d204dfdb33
Signed-off-by: Pavankumar Kondeti <pkondeti@codeaurora.org>
Diffstat (limited to 'Documentation/scheduler')
| -rw-r--r-- | Documentation/scheduler/sched-hmp.txt | 17 |
1 files changed, 17 insertions, 0 deletions
diff --git a/Documentation/scheduler/sched-hmp.txt b/Documentation/scheduler/sched-hmp.txt index 22449aec5558..b400e053e55d 100644 --- a/Documentation/scheduler/sched-hmp.txt +++ b/Documentation/scheduler/sched-hmp.txt @@ -1220,6 +1220,23 @@ This tunable is a percentage. Configure the minimum demand of big sync waker task. Scheduler places small wakee tasks woken up by big sync waker on the waker's cluster. +*** 7.19 sched_prefer_sync_wakee_to_waker + +Appears at: /proc/sys/kernel/sched_prefer_sync_wakee_to_waker + +Default value: 0 + +The default sync wakee policy has a preference to select an idle CPU in the +waker cluster compared to the waker CPU running only 1 task. By selecting +an idle CPU, it eliminates the chance of waker migrating to a different CPU +after the wakee preempts it. This policy is also not susceptible to the +incorrect "sync" usage i.e the waker does not goto sleep after waking up +the wakee. + +However LPM exit latency associated with an idle CPU outweigh the above +benefits on some targets. When this knob is turned on, the waker CPU is +selected if it has only 1 runnable task. + ========================= 8. HMP SCHEDULER TRACE POINTS ========================= |