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SubjectRe: Performance loss 2.6.22->22.6.23->2.6.24-rc7 on CPU intensive benchmark on 8 Core Xeon

* Colin Fowler <elethiomel@gmail.com> wrote:

> Hi Ingo, I'll need to convince my supervisor first if I can release a
> binary. Technically anythin glike this needs to go through our
> University's "innovations department" and requires lengthy paperwork
> and NDAs :(.

a binary wouldnt work for me anyway. But you could try to write a
"workload simulator": just pick out the pthread ops and replace the
worker functions with some dummy stuff that just touches an array that
has similar size to the tiles (in a tight loop). Make sure it has
similar context-switch rate and idle percentage as your real workload -
then send us the .c file. As long as it's a single .c file that runs for
a few seconds and outputs a precise enough "run time" result, kernel
developers would pick it up and use it for optimizations. To get the #
of cpus automatically you can do:

cpus = system("exit `grep processor /proc/cpuinfo | wc -l`");
cpus = WEXITSTATUS(cpus);

and start as many threads as many CPUs there are in the system.

Ingo


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