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

To: "Keir Fraser" <Keir.Fraser@xxxxxxxxxxxx>, "Espen Skoglund" <espen.skoglund@xxxxxxxxxxxxx>, <xen-devel@xxxxxxxxxxxxxxxxxxx>
Subject: RE: [Xen-devel] Ticket spinlocks and MP guests
From: "Tian, Kevin" <kevin.tian@xxxxxxxxx>
Date: Fri, 15 Feb 2008 16:27:33 +0800
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Thread-topic: [Xen-devel] Ticket spinlocks and MP guests
>From: Keir Fraser
>Sent: 2008年2月15日 16:23
>On 15/2/08 01:03, "Tian, Kevin" <kevin.tian@xxxxxxxxx> wrote:
>>> I suppose it depends whether there are any hot spinlocks in
>>> the kernel these
>>> days. I know things have improved a lot in recent years with
>>> things like
>>> RCU. Most spinlock regions are now pretty short.
>> The side effect is to enlarge average critical section length, if
>> most spinlock regions are pretty short.
>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? 


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