Re: [PATCH RT 00/02] SLOB optimizations

[Zwane Mwaikambo <zwane@arm.linux.org.uk>]

On Thu, 22 Dec 2005, Eric Dumazet wrote:

> Ingo Molnar a écrit :
> > 
> > CLI/STI is extremely fast. (In fact in the -rt tree i'm using them within
> > mutexes instead of preempt_enable()/preempt_disable(), because they are
> > faster and generate less register side-effect.)
> > 
> 
> Yes, but most of my machines have a ! CONFIG_PREEMPT kernel, so
> preempt_enable()/preempt_disable() are empty, thus faster than CLI/STI for
> sure :)
> 
> Then, maybe the patch that moves 'current' in a dedicated x86_64 register may
> help to lower  the cost of preempt_enable()/preempt_disable() on a
> CONFIG_PREEMPT kernel ?

I'm not sure if it'll make much of a difference over;

mov    %gs:offset,%reg

So 'current' already is fairly fast on x86_64.