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

[Andi Kleen]

On Tuesday 04 July 2006 23:19, Chuck Ebbert wrote:
> In-Reply-To: <20060704072939.GC5902@xxxxxxxxxxxxxxxxx>
>
> On Tue, 4 Jul 2006 00:29:39 -0700, Stephane Eranian wrote:
> > Following my discussion with Andi. Here is a patch that introduces
> > two new TIF flags to simplify the context switch code in __switch_to().
> > The idea is to minimize the number of cache lines accessed in the common
> > case, i.e., when neither the debug registers nor the I/O bitmap are used.
>
> 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.

-Andi
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