Re: x86: Is there still value in having a special tlb flush IPI vector?

[Andi Kleen]

On Mon, Jul 28, 2008 at 11:29:18PM -0700, Jeremy Fitzhardinge wrote:
> Andi Kleen wrote:
> >>>Now that normal smp_function_call is no longer an enormous bottleneck, 
> >>>      
> >
> >Hmm? It still uses a global lock at least as of current git tree.
> 
> Yes, but it's only held briefly to put things onto the list.  It doesn't 
> get held over the whole IPI transaction as the old smp_call_function 
> did, and the tlb flush code still does.  RCU is used to manage the list 
> walk and freeing, so there's no long-held locks there either.

If it bounces regularly it will still hurt.

-Andi
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