Re: 2.6.16-rc6-mm2

[Andi Kleen]

On Tuesday 13 June 2006 07:08, Keith Owens wrote:
> Andi Kleen (on Tue, 13 Jun 2006 06:56:45 +0200) wrote:
> >
> >> I have previously suggested a lightweight solution that pins a process
> >> to a cpu 
> >
> >That is preempt_disable()/preempt_enable() effectively
> >It's also light weight as much as these things can be.
> 
> The difference being that preempt_disable() does not allow the code to
> sleep.  There are some places where we want to use cpu local data 
> and 
> the code can tolerate preemption and even sleeping, as long as the
> process schedules back on the same cpu.

Seems like a pretty obscure case to optimize for.

Anyways if you want to do that you can always do

disable_preempt(); 
set thread affinity mask to current cpu
enable_preempt(); 
do weird stuff and sleep ...  ;
restore affinity mask

Can any of these people proposing "solutions" in this thread
demonstrate this stuff is actually performance critical?

-Andi
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