Re: Bug: 2.6.15 Process accounting fails to account for small time slice loads (still)

[Christian Borntraeger <borntrae@de.ibm.com>]

On Tuesday 30 January 2007 17:24, you wrote:
> The bug described back in 2004 in the following message still seems to 
exist:
> 
> http://linux.derkeiler.com/Mailing-Lists/Kernel/2004-05/4313.html
> 
> Essentially, it appears that if a process sleeps before it uses up a
> complete jiffy then no charge is made to its process accounting table.
> 
> This problem still exists in the same manner in kernel:

This is a known limitation of tick based accounting used on most 
architectures. 
It was fixed on s390 and using a cpu timer on every context switch. (IIRC ppc 
is now using this infrastructure as well)

see for a http://www.kernel-traffic.org/kernel-traffic/kt20041117_284.html#8
for the first patch in the series.

I dont know if there are plans of using the infrastructure on x86 compatible 
platforms. I also dont know it that is actually easy to implement with x86 
hardware. 




-- 
Mit freundlichen Grüßen / Best Regards

Christian Borntraeger
Linux Software Engineer zSeries Linux & Virtualization