Re: [PATCH 2/2] i386 TIF flags for debug regs and io bitmap in ctxsw

From: Chuck Ebbert
Date: Wed Jul 05 2006 - 07:48:04 EST


In-Reply-To: <200607042347.00598.ak@xxxxxxx>

On Tue, 4 Jul 2006 23:47:00 +0200, Andi Kleen wrote:

> > I get a 5-10% speedup in task switch times with this patch.
>
> That sounds too much. How did you measure it?
>
> Note that lmbench tends to be unstable for this.

I used lmbench's lat_ctx(8). According to its manpage, you can make
multiple runs and use the minimum, not the average.

And the gain may have been high because I tested on an old PII notebook
with small cache and slow memory.

--
Chuck
"You can't read a newspaper if you can't read." --George W. Bush
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