Messages in this thread | | | Date | Mon, 27 Nov 2006 10:41:20 -0800 | From | Max Krasnyansky <> | Subject | Re: [patch] x86: unify/rewrite SMP TSC sync code |
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> Using gtod() can amount to a substantial disturbance of the thing to > be measured. Using rdtsc, things seem reliable so far, and we have an > FPGA (accessed through the PCI bus) that has been programmed to give > access to an 8MHz clock and we do some checks against that.
Same here. gettimeofday() is way too slow (dual Opteron box) for the frequency I need to call it at. HPET is not available. But TSC is doing just fine. Plus in my case I don't care about sync between CPUs (thread that uses TSC is running on the isolated CPU) and I have external time source that takes care of the drift.
So please no trapping of the RDTSC. Making it clear (bold kernel message during boot :-) that TSC(s) are not in sync or unstable (from GTOD point of view) is of course perfectly fine.
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