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Re: [Xen-devel] Ticket spinlocks and MP guests

To: "Tian, Kevin" <kevin.tian@xxxxxxxxx>, Espen Skoglund <espen.skoglund@xxxxxxxxxxxxx>, <xen-devel@xxxxxxxxxxxxxxxxxxx>
Subject: Re: [Xen-devel] Ticket spinlocks and MP guests
From: Keir Fraser <Keir.Fraser@xxxxxxxxxxxx>
Date: Fri, 15 Feb 2008 08:36:40 +0000
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On 15/2/08 08:27, "Tian, Kevin" <kevin.tian@xxxxxxxxx> wrote:

>> Side effect of ticket-based locks, or pv'ed sleeping locks?
>> -- Keir
> Side effect about pv'ed sleeping locks, since originally maybe
> dozens of cycles are used to spin lock while pv'ed locks force
> hypercall to Xen and may even require owner with another
> unlock hypercall to notify back?

You would of course spin for a while and only then sleep. That's a standard
mutex implementation trick.

 -- Keir

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