Re: [PATCH v6 4/6] locking/pvqspinlock: Collect slowpath lock statistics

[Davidlohr Bueso]

On Fri, 11 Sep 2015, Waiman Long wrote:

> A sample of statistics counts after system bootup (with vCPU
> overcommit) was:
>
> hash_hops_count=9001
> kick_latencies=138047878
> kick_unlock_count=9001
> kick_wait_count=9000
> spurious_wakeup=3
> wait_again_count=2
> wait_head_count=10
> wait_node_count=8994
> wake_latencies=713195944

Any reason you chose not to make the stats per-cpu? The locking
numbers don't have to be exact, so you can easily get away with
it and suffer from much less overhead that resorting to atomics.
Obviously assuming that reading/collecting the stats is done
infrequently, such as between workloads or at bootup as you did.

Thanks,
Davidlohr
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