Re: [PATCH 10/17] 2.6.17.1 perfmon2 patch for review: PMU context switch

[Andi Kleen]

On Monday 03 July 2006 21:22, Stephane Eranian wrote:
> Andi,
> 
> On Mon, Jul 03, 2006 at 09:25:48PM +0200, Andi Kleen wrote:
> > On Monday 03 July 2006 11:49, Stephane Eranian wrote:
> > > Andi,
> > > 
> > > Here is a first cut at the patch to simplify the context
> > > switch for the common case and also touch 2 cachelines (instead of 3).
> > > There are 2 new TIF flags. I just tried this on x86_64 but I believe
> > > we could do the same on i386.
> > > 
> > > Is that what you were thinking about?
> > 
> > Yes, looks good.
> > 
> I have worked on this some more and I also looked at i386.
> They seem to handle the io bitmap differently there. At least
> they seem to have some lazy scheme whereby you do not reinstall
> if new task is the last owner of tss. Is there a reason for not
> having this in place for x86-64?

There was a reason but I can't remember it right now :/ Something
in the new scheme didn't fit well or it was just too complicated.

-Andi

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