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Re: [Xen-devel] [PATCH RFC V4 0/5] kvm : Paravirt-spinlock support for KVM guests

On 01/25/2012 10:05 PM, Konrad Rzeszutek Wilk wrote:
So it seems we have worst case overhead of around 8%. But we see
improvement of at-least 15% once when little more time is spent in
critical section.

Is this with collecting the histogram information about spinlocks? We found
that if you enable that for production runs it makes them quite slower.

Ok. Are you referring to CONFIG_KVM_DEBUG_FS/CONFIG_XEN_DEBUG_FS?. Not
it was not enabled. But then may be I was not precise. This test was only on native. So it should have not affected IMO.

It is nice to know that histogram affects, since I was always under the
impression that it does not affect much on guest too. My experiments
had almost always enabled that.

Let me know if you referred to something else..

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