Re: [linux-pm] [uclinux-dist-devel] freezer: should barriers besmp ?

[Pavel Machek]

Hi!

> > > I believe the code is correct as is.
> > 
> > that isnt what the code / documentation says.  unless i'm reading them
> > wrong, both seem to indicate that the proposed patch is what we
> > actually want.
> 
> The existing code is correct but it isn't optimal.
> 
> wmb() and rmb() are heavy-duty operations, and you don't want to call
> them when they aren't needed.  That's exactly what smp_wmb() and
> smp_rmb() are for -- they call wmb() and rmb(), but only in SMP 
> kernels.
> 
> Unless you need to synchronize with another processor (not necessarily 
> a CPU, it could be something embedded within a device), you should 
> always use smp_wmb() and smp_rmb() rather than wmb() and rmb().

Maybe; but this code is not performance critical and I believe being
obvious here is better...
									Pavel
-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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