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Re: [Xen-devel] Linux spin lock enhancement on xen

To: Mukesh Rathor <mukesh.rathor@xxxxxxxxxx>
Subject: Re: [Xen-devel] Linux spin lock enhancement on xen
From: Jeremy Fitzhardinge <jeremy@xxxxxxxx>
Date: Tue, 17 Aug 2010 10:43:04 -0700
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 On 08/16/2010 06:33 PM, Mukesh Rathor wrote:
> In my worst case test scenario, I get about 20-36% improvement when the
> system is two to three times over provisioned. 
> Please provide any feedback. I would like to submit official patch for
> SCHEDOP_yield_to in xen.

This approach only works for old-style spinlocks.  Ticketlocks also have
the problem of making sure the next vcpu gets scheduled on unlock.

Have you looked at the pv spinlocks I have upstream in the pvops
kernels, which use the (existing) poll hypercall to block the waiting
vcpu until the lock is free?


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