Messages in this thread | | | Date | Tue, 17 Dec 2002 16:53:37 -0500 | From | Benjamin LaHaise <> | Subject | Re: Intel P6 vs P7 system call performance |
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On Tue, Dec 17, 2002 at 01:41:55PM -0800, H. Peter Anvin wrote: > > No, just take the number of context switches before and after the attempt > > to read the time of day.
> How do you do that from userspace, atomically? A counter in the shared > page?
Yup. You need some shared data for the TSC offset such anyways, so moving the context switch counter onto such a page won't be much of a problem. Using the %tr trick to get the CPU number would allow for some of these data structures to be per-cpu without incurring any LOCK overhead, too.
-ben -- "Do you seek knowledge in time travel?" - 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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