Re: [Patch 2/7] Add sysctl for schedstats

Nick Piggin
2006-02-27T12:28:22Z

Shailabh Nagar wrote:
> Nick Piggin wrote:

>>
>> And clearing this at all is not really needed for the schedstats
>> interface.
>> You have a timestamp and a set of accumulated values, so it is easy to
>> work
>> out deltas. So do you need this?
>
>
> Not clearing the stats will mean userspace has to distinguish between
> the tasks
> that are hanging around from before the last turn off, and the ones
> created after
> wards. Any delta taken across an interval where schedstats was turned
> off will
> give the impression a task was sleeping during the interval (and hence
> show it had
> a lesser average wait time than it might actually have experienced).

Presumably a delta taken acrsoss an interval where schedstats
was turned off would be rather inaccurate, no matter what.

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SUSE Labs, Novell Inc.
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