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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] Re: [PATCH 3/5] x86/pvclock: add vsyscall implementation
On Wed, Oct 28, 2009 at 07:52:04AM +0200, Avi Kivity wrote: > On 10/27/2009 08:20 PM, Jeremy Fitzhardinge wrote: >> On 10/27/09 10:29, Dan Magenheimer wrote: >> >>> Is there any way for an application to conclusively determine >>> programmatically if the "fast vsyscall" pvclock is functional >>> vs the much much slower gettimeofday/clock_gettime equivalents? >>> >>> If not, might it be possible to implement some (sysfs?) >>> way to determine this, that would also be backwards compatible >>> to existing OS's that don't have pvclock+vsyscall supported? >>> >>> >> It would probably be simplest and most portable for the app to just >> measure the performance of gettimeofday and see if it meets its needs. >> > > How can you reliably measure performance in a virtualized environment? If we loop gettimeofday(), I would expect the vsyscall-based version not to show up in strace, right? _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxxxxxxxx http://lists.xensource.com/xen-devel
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