On Mon, Oct 19, 2015 at 1:04 AM, Ingo Molnar <mi...@kernel.org> wrote:
>
> triton:~> perf bench mem all
> # Running mem/memcpy benchmark...
> Routine default (Default memcpy() provided by glibc)
> 4.957170 GB/Sec (with prefault)
> Routine x86-64-unrolled (unrolled memcpy() in
> arch/x86/lib/memcpy_64.S)
> 4.379204 GB/Sec (with prefault)
> Routine x86-64-movsq (movsq-based memcpy() in
> arch/x86/lib/memcpy_64.S)
> 4.264465 GB/Sec (with prefault)
> Routine x86-64-movsb (movsb-based memcpy() in
> arch/x86/lib/memcpy_64.S)
> 6.554111 GB/Sec (with prefault)
Is this skylake? And why are the numbers so low? Even on my laptop
(Haswell), I get ~21GB/s (when setting cpufreq to performance).
It's interesting that 'movsb' for you is so much better. It's been
promising before, and it *should* be able to do better than manual
copying, but it's not been that noticeable on the machines I've
tested. But I haven't ued Skylake or Broadwell yet.
cpufreq might be making a difference too. Maybe it's just ramping up
the CPU? Or is that really repeatable?
Linus
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