On 05/21/2014 06:54 PM, Fengguang Wu wrote:
>>>
>>> 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%.
>
That would be consistent with spending less time in the kernel, no?
But I agree... that is completely bizarre. That checkin should have
absolutely zero effect on performance.
-hpa
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