Re: [patch] sched: accurate user accounting

From: malc
Date: Fri Jun 15 2007 - 02:08:44 EST


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
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