Hi Andy,
On Wed, May 21, 2014 at 03:46:58PM -0700, Andy Lutomirski wrote:
> On Mon, May 19, 2014 at 10:59 PM, Jet Chen <jet.c...@intel.com> 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?
It's a speedup. The will-it-scale/sched_yield test case's throughput
increased by +14.7% (multi-thread case) and +1.6% (multi-process case).
However the CPU %user time increased more, by +48.9%.
Thanks,
Fengguang
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