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SubjectRe: [patch] sched: accurate user accounting
malc wrote:
> On Fri, 15 Jun 2007, Balbir Singh wrote:
>
>> malc wrote:
>>> On Thu, 14 Jun 2007, Ingo Molnar wrote:
>>>
>
> [..snip..]
>
>>>
>>> Now integral load matches the one obtained via the "accurate" method.
>>> However the report for individual cores are of by around 20% percent.
>>>
>>
>> I think I missed some of the context, is the accounting of individual
>> tasks
>> or cpustat values off by 20%? I'll try and reproduce this problem.
>
> Neither actually, the individual core idle times reported via `/proc/stat'
> are off by 20 percent, one over estimates and the other under estimates
> and the sum is right on the mark.
>

Interesting, the idle time accounting (done from account_system_time())
has not changed. Has your .config changed? Could you please send
it across. I've downloaded apc and I am trying to reproduce your problem.

>>
>> Could you provide more details on the APC tool that you are using -- I
>> do not understand the orange and yellow lines, do they represent system
>> and user time?
>
> It's somewhat documented on the page: http://www.boblycat.org/~malc/apc
> Anyway the left bar is based on information from `/proc/stat' the right
> one is derived from the kernel module that just times how much time was
> spent in idle handler. The graphs: red - `/proc/stat', yellow - module.
>
>> NOTE: There is some inconsistency in the values reported by /usr/bin/time
>> (getrusage) and values reported in /proc or through delay accounting.
>
> I don't really use `getrusage'.
>

Tools like /usr/bin/time do.

--
Warm Regards,
Balbir Singh
Linux Technology Center
IBM, ISTL
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