Some tips for benchmarking

[Johannes Doerfert via llvm-commits]

On 10/24, David Blaikie via llvm-commits wrote:
> (might be worth mentioning on llvm-dev - could get lost on commits)
Right. It took me a while to find this thread again as the different
lists are sorted into separated folders. Additionally, not everyone that
might be interested in this discussion follows llvm-commits.

> Maybe even writing up as documentation on the website somewhere - runtime
> analysis has always been a real pain for me to get reliable numbers, so I'm
> really glad for any/all tips I can find when I end up dealing with it.
> 
> On Wed, Oct 19, 2016 at 7:39 PM Rafael Espíndola via llvm-commits <
> llvm-commits at lists.llvm.org> wrote:
> 
> > After much pain I decided that instead of just running tests many
> > times I should put some effort in figuring out why perf numbers were
> > so hard to reproduce on my machine.
> >
> > I was already disabling address space randomization and setting the
> > scaling_governor to performance. Other things I found
> >
> > * Use https://github.com/lpechacek/cpuset to reserve a cpu for just
> > the program you are benchmarking.
> > * Disable the SMP pair (echo 0 > /sys/devices/system/cpu/cpuX/online)
> > of the cpu you will use for the benchmark.
> > * disable turbo mode (echo 1 >
> > /sys/devices/system/cpu/intel_pstate/no_turbo).
> >
> > The results are pretty awesome:
> >
> > 3.012355647 seconds time elapsed         ( +-  0.01% )
> >
> > :-)
> >
> > Cheers,
> > Rafael
> > _______________________________________________
> > llvm-commits mailing list
> > llvm-commits at lists.llvm.org
> > http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-commits
> >

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-- 

Johannes Doerfert
Researcher / PhD Student

Compiler Design Lab (Prof. Hack)
Saarland Informatics Campus, Germany
Building E1.3, Room 4.31

Tel. +49 (0)681 302-57521 : doerfert at cs.uni-saarland.de
Fax. +49 (0)681 302-3065  : http://www.cdl.uni-saarland.de/people/doerfert
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