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SubjectRe: [PATCH v3 3/7] locking/pvqspinlock: Collect slowpath lock statistics
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On Wed, 2015-07-22 at 16:12 -0400, Waiman Long wrote:
> This patch enables the accumulation of kicking and waiting related
> PV qspinlock statistics when the new QUEUED_LOCK_STAT configuration
> option is selected. It also enables the collection of kicking and
> wakeup latencies which have a heavy dependency on the CPUs being used.
>
> The measured latencies for different CPUs are:
>
> CPU Wakeup Kicking
> --- ------ -------
> Haswell-EX 89.8us 7.4us
> Westmere-EX 67.6us 9.3us
>

But you don't mention anything about the overhead of enabling
QUEUED_LOCK_STAT. This does several atomic ops, thus potentially
thrashing workloads.



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