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

From: Raghavendra K T
Date: Mon May 07 2012 - 21:14:12 EST


On 05/08/2012 04:45 AM, Jeremy Fitzhardinge wrote:
On 05/07/2012 06:49 AM, 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?

How does PLE help with ticket scheduling on unlock? I thought it would
just help with the actual spin loops.

Hmm. This strikes something to me. I think I should replace while 1 hog
in with some *real job* to measure over-commit case. I hope to see
greater improvements because of fairness and scheduling of the
patch-set.

May be all the way I was measuring something equal to 1x case.

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