Re: [PATCH RFC V8 0/17] Paravirtualized ticket spinlocks

Raghavendra K T <raghavendra.kt@xxxxxxxxxxxxxxxxxx> · Mon, 07 May 2012 19:23:59 +0530

On 05/07/2012 07:19 PM, Avi Kivity wrote:

On 05/07/2012 04:46 PM, Srivatsa Vaddagiri wrote:

* Raghavendra K T<raghavendra.kt@xxxxxxxxxxxxxxxxxx>  [2012-05-07 19:08:51]:

I 'll get hold of a PLE mc  and come up with the numbers soon. but I
'll expect the improvement around 1-3% as it was in last version.

Deferring preemption (when vcpu is holding lock) may give us better than 1-3%
results on PLE hardware. Something worth trying IMHO.

Is the improvement so low, because PLE is interfering with the patch, or
because PLE already does a good job?

It is because PLE already does a good job (of not burning cpu). The
1-3% improvement is because, patchset knows atleast who is next to hold
lock, which is lacking in PLE.

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