Re: Error in x86 CPU capabilities starting with test5/6

From: Andi Kleen (ak@suse.de)
Date: Fri Nov 17 2000 - 08:31:50 EST


On Fri, Nov 17, 2000 at 02:21:03PM +0100, Christoph Rohland wrote:
> Hi Jeff,
>
> On Fri, 17 Nov 2000, Jeff Garzik wrote:
> > IIRC, this came up a long time ago WRT Apache, which made a lot of
> > gettimeofday() calls. Someone (Linus?) proposed the solution of a
> > 'magic page' which holds information like gettimeofday() stuff, but
> > could be handled much more rapidly than a standard syscall.
>
> Yes, I followed that thread closely and would love to see this as the
> implementation for gettimeofday. This would make rdtsc for
> applications superfluous.

No it would not. Often you want cycle accurate couting for profiling
purposes.

-Andi
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