[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] RE: [Xen-devel] Ticket spinlocks and MP guests
>From: Keir Fraser [mailto:Keir.Fraser@xxxxxxxxxxxx] >Sent: 2008年2月15日 16:37 > >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. > I'm not sure how to define 'a while', since even for same critical section the spin cycles varies at different point. You always risk adding more overhead than a normal spin loop. But well, it depends on how frequent forementioned case may occur, and the gain of pv'ed spinlock may be larger than overhead it causes. Thanks, Kevin _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxxxxxxxx http://lists.xensource.com/xen-devel
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