Inaccurate process time accounting

[Jan Astalos]

Hi all.

I'm working on monitoring system for Linux clusters and I need to get
dynamicaly CPU time consumed by process (no matter in which mode) for
performance prediction. It seems that time accounting in my kernel
(2.2.14) does not count time slices shorter than one jiffie. I made
process that runs for less than jiffie and then sleeps one jiffie (in
cycle). Although benchmarking showed that test takes around 30% of CPU
time, accounting said that it had consumed less than 1%.

I tested patch from Pavel Machek
http://www.tux.org/hypermail/linux-kernel/1999week20/0232.html

Results are more accurate but only if there is no other CPU bound
process. 
Changing HZ helped but I don't want to increase kernel overhead. 

Can be TSC used for this ? Is there any patch ?

Please, cc the answers to my address.
Thanks in advance.

Jan

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