Re: [x86, vdso] cfda7bb9ecb: +14.7% will-it-scale.per_thread_ops

[Andy Lutomirski]

On Mon, May 19, 2014 at 10:59 PM, Jet Chen <jet.chen@xxxxxxxxx> wrote:
> Hi Andy,
>
> FYI, we noticed the below changes on
>
> git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git x86/vdso
> commit cfda7bb9ecbf9d96264bb5bade33a842966d1062 ("x86, vdso: Move syscall
> and sysenter setup into kernel/cpu/common.c")

This is really strange.  That change shouldn't have any effect except
that some kernels might boot a cycle or two faster.

>
> test case: nhm4/will-it-scale/sched_yield
>
> 3d7ee969bffcc98  cfda7bb9ecbf9d96264bb5bad
> ---------------  -------------------------
>     5497021 ~ 0%     +14.7%    6303424 ~ 0%  TOTAL
> will-it-scale.per_thread_ops
>        0.54 ~ 0%      +5.6%       0.57 ~ 0%  TOTAL will-it-scale.scalability
>     6209483 ~ 0%      +1.6%    6305917 ~ 0%  TOTAL
> will-it-scale.per_process_ops
>        2455 ~ 5%     +16.9%       2870 ~ 5%  TOTAL cpuidle.C1-NHM.usage
>        8829 ~ 7%     +15.2%      10169 ~10%  TOTAL
> slabinfo.kmalloc-64.active_objs
>       24.13 ~12%     +48.9%      35.93 ~14%  TOTAL time.user_time
>         393 ~ 0%      -3.0%        382 ~ 1%  TOTAL time.system_time
>

Is this a speedup or a slowdown?

--Andy
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