Re: [PATCH] sched: Update scheduler stat documentation.

From: Rakib Mullick
Date: Mon Jan 16 2012 - 03:23:10 EST


On Mon, Jan 16, 2012 at 1:56 PM, Ingo Molnar <mingo@xxxxxxx> wrote:
>
> * Rakib Mullick <rakib.mullick@xxxxxxxxx> wrote:
>
>> /proc/schedstat's second field reflect to # of time context switch happened not # of times switched to the expired queue.
>>
>> Signed-off-by: Rakib Mullick <rakib.mullick@xxxxxxxxx>
>> ---
>>
>> diff --git a/Documentation/scheduler/sched-stats.txt b/Documentation/scheduler/sched-stats.txt
>> index 1cd5d51..7d8e12c 100644
>> --- a/Documentation/scheduler/sched-stats.txt
>> +++ b/Documentation/scheduler/sched-stats.txt
>> @@ -38,7 +38,8 @@ First field is a sched_yield() statistic:
>>       1) # of times sched_yield() was called
>>
>>  Next three are schedule() statistics:
>> -     2) # of times we switched to the expired queue and reused it
>> +     2) # of times context switch happened. This field is not utilized these
>> +     days but kept for holding userspace tools integrity.
>
> if it's not used by anything but kept for the ABI then we should
> not put context switch number in there, but always keep it zero,
> right?
>
Yes, quite right. It is a bit confusing. Anyone might have think that
context switch numbers are 0. So, instead of saying "# of times
context switch happened", we can say, "This field has been kept for
ABI integrity". Right?

Thanks,
Rakib
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