Messages in this thread |  | | Date | Thu, 16 Jan 2003 19:34:57 -0500 | From | Jim Houston <> | Subject | Re: [PATCH] improved boot time TSC synchronization |
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Jamie Lokier wrote: > > It looks like not only can you synchronise with a certain accuracy, > you can determine an upper bound on that accuracy (assuming the > underlying CPU clocks are locked). > > Maybe that figure could be put into /proc/cpuinfo? > > As well as being an interesting value, it may be useful for programs > to know the effective accuracy of `rdtsc'. > > -- Jamie
Hi Jamie,
Yeah, I'd be glad to add the round-trip time to cpuinfo. I see this as a bogomips like metric. It tells you how quickly you can move cache lines from chip to chip.
The patch currently prints the round-trip time and the max_delta. On a Quad P4 Xeon, I got round-trip times in the 0.7 microsecond range which is disappointing. The max_delta was almost always zero cycles meaning that the feedback loop thinks that the TSC values are perfectly synchronized.
Jim Houston - Concurrent Computer Corp. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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