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

From: Lee Revell
Date: Mon Jun 20 2005 - 13:09:01 EST

On Mon, 2005-06-20 at 10:09 -0700, john stultz wrote:
> As for gettimefoday() syscall performance, I one had some numbers, but
> I
> would need to re-create them. I'll see if I can grab a slower box and
> give you some hard numbers.

I ran some tests lately that showed gettimeofday() to be 50x slower than
rdtsc() on my 600Mhz machine. Many userspace apps that need a cheap
high res timer have to use rdtsc now due to the excessive overhead of
gettimeofday(). It would be more correct if these apps could use
gettimeofday() for various reasons (cpufreq and SMP issues).

So this patch is addressing a real problem. I'd be interested to see if
the performance is good enough to replace rdtsc in these cases.


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