Some tips for benchmarking
Michael Kruse via llvm-commits
llvm-commits at lists.llvm.org
Wed Oct 26 11:07:11 PDT 2016
2016-10-20 4:39 GMT+02:00 Rafael Espíndola via llvm-commits
<llvm-commits at lists.llvm.org>:
> 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% )
Cool. Would it be possible to teach lnt runtests to do that by itself?
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