Re: [patch] sched: accurate user accounting

[malc <av1474@comtv.ru>]

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.

>
> 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'.

-- 
vale