[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] rdtscP and xen (and maybe the app-tsc answer I've been looking for)
On 09/22/09 12:36, Dan Magenheimer wrote: > Are you (Jeremy) still assuming that rdtsc/rdtscp are NOT > emulated? Or are you trying to define a vsyscall+pvclock > mechanism for the same constrained environments > so that HFTSAs have a choice of using clock_gettime > instead of pvrdtsc, either of which will be fast? > Yes, I'm assuming they're not emulated. If you're emulating them there's no reason to add any extra complexity to usermode by adding any other ABI: rdtsc can be rdtsc and rdtscp can be rdtscp with no Xen/ABI-imposed constraints on TSC_AUX. Once you're talking about layering another ABI onto the tsc, then there's no need to consider emulation because you can do all the necessary correction to get a canonical timestamp without it. J _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxxxxxxxx http://lists.xensource.com/xen-devel
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