Re: [PATCH -mm 1/2] irq_work, Use llist in irq_work

[Peter Zijlstra]

On Fri, 2011-09-02 at 09:18 +0800, Huang Ying wrote:
> On 09/01/2011 06:00 PM, Peter Zijlstra wrote:
> > On Thu, 2011-09-01 at 16:44 +0800, Huang Ying wrote:
> > 
> >> Because llist is in library, it may be used in highly contended case and
> >> light/un-contended loads.  So maybe code as above is best choice for llist.
> > 
> > Well the thing is, if you're heavily contended you should probably be
> > doing something else..
> 
> So which solution is preferable?
> 
> 1) no cpu_relax
> 2) cpu_relax after first cmpxchg
> 
> Personally, I prefer 2).  It should have acceptable overhead in
> ligh/un-contended loads.  Do you agree.

I guess so, we can always poke at it again when someone finds something
to measure.
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