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RE: [Xen-devel] [PATCH] Yield to VCPU hcall, spinlock yielding

To: "Ryan Harper" <ryanh@xxxxxxxxxx>, <xen-devel@xxxxxxxxxxxxxxxxxxx>
Subject: RE: [Xen-devel] [PATCH] Yield to VCPU hcall, spinlock yielding
From: "Ian Pratt" <m+Ian.Pratt@xxxxxxxxxxxx>
Date: Fri, 3 Jun 2005 21:41:31 +0100
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Thread-topic: [Xen-devel] [PATCH] Yield to VCPU hcall, spinlock yielding
> I've not recieved any feedback on this.  Following this patch 
> up with one that applies against current.  Builds, but 
> haven't tested it since current SMP domains don't run.  

Steven Smith has been experimenting with and benchmarking a number of
different variants of this approach, testing a range of different
preemption mitigation and avoidance techniques. I'm sure we'll hear more
next week...

My gut feeling is that we can get away with something simpler than the
confer technique as we only need it as a hint. Anyhow, lets see.

Have you any suggestions for metrics for comparing the schemes? lmbench
is quite good for assessing the no contenion case. Perhaps doing a
kernel build on a guest with VCPUs > phy CPUs is a reasonable way of
assesing the benefit.


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