Re: [PATCH] faster signal handling on x86

[Linus Torvalds]

On Tue, 26 Oct 2004, Zachary Amsden wrote:
>
> I noticed an unneeded write to dr7 in the signal handling path for x86.  
> We only need to write to dr7 if there is a breakpoint to re-enable, and 
> MOVDR is a serializing instruction, which is expensive.  Getting rid of 
> it gets a 33% faster signal delivery path (at least on Xeon - I didn't 
> test other CPUs, so your gain may vary).

I'm suprised it is _that_ slow, but sure, no problem, the patch just makes 
it match all the other paths. 

I suspect Xeon is alone in being _that_ slow - I bet Netburst flushes the 
whole trace cache on db7 writes.

		Linus
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