Re: [PATCH 1/6] new timeofday core subsystem for -mm (v.B3)

From: Lee Revell
Date: Mon Jun 20 2005 - 20:29:11 EST

On Mon, 2005-06-20 at 14:53 -0700, john stultz wrote:
> Yea, honestly I doubt gettimefoday performance will ever be as good as
> rdtsc. I mean, that's a single instruction vs syscall overhead +
> hardware clock reading + frequency conversion + ntp adjustment. Its
> just not a fair comparison.

Of course not, the patch would have to be magic for that to happen.

But some user space apps are now *required* to use rdtsc for timing due
to the massive performance difference. If we only took a 5x or 10x
performance hit vs rdtsc, rather than the current 50x, it might be
enough that user space apps won't have to do this.


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