[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH 1/2] cpu steal time accounting
On Wed, 22 Feb 2006, Keir Fraser wrote: > Is accounting user/system time an unnecessary extra? I guess we already > do it by sampling at tick granularity anyway? > > Should 'steal time' include blocked time when the guest had no work to > execute? No, this is idle time. If the guest had no work to do, it wasn't suffering from contention of the CPU. > Also, given the logic currently only triggers when the guest detects it > 'missed a tick', would it be good enough simply to account #missed_ticks as > steal time. It would certainly be a lot simpler to implement, and you end up > dividing everything down to tick granularity anyway. :-) Not good enough if the hypervisor ends up scheduling guests on a granularity finer than the guest's own timer ticks. The reason for only checking steal time when we miss a tick is that I don't want to run the (expensive?) steal time logic on every timer interrupt. -- All Rights Reversed _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxxxxxxxx http://lists.xensource.com/xen-devel
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