Re: [PATCH] Preemption Latency Measurement Tool

Andre Pang
2001-09-22T03:58:07Z

On Wed, Sep 19, 2001 at 06:44:09PM -0400, Robert Love wrote:

> Available at:
> http://tech9.net/rml/linux/patch-rml-2.4.9-ac12-preempt-stats-1 and
> http://tech9.net/rml/linux/patch-rml-2.4.10-pre12-preempt-stats-1
> for 2.4.9-ac12 and 2.4.10-pre12, respectively.

hi Robert, thanks for producing the stats patches!

i did a test of it on linux-2.4.10-pre13 with Benno Senoner's
lowlatency program, which i hacked up a bit to output
/proc/latencytimes after each of the graphs. test results are at

http://www.algorithm.com.au/hacking/linux-lowlatency/2.4.10-pre13-pes/

and since i stared at the results in disbelief, i won't even try
to guess what's going on :). maybe you can make some sense of
it?

i'm prety sure his latencytest program runs at real-time
priority, but i'll run another test just with the getrt and rt
programs just posted to the list to make sure. that's the only
reason i can think why the graph is so bizarre compared to the
/proc/latencytimes results.

--