On Tue, Jun 05, 2007 at 11:38:27AM -0700, Luck, Tony wrote:
> > So is
> >
> > while (__raw_spin_is_locked(&v));
> >
> > supposed to work? Or should that be
> >
> > while (__raw_spin_is_locked(&v))
> > cpu_relax();
> >
> > as well and all the volatiles can/should go away?
>
> cpu_relax() is a really good idea in every spinloop on
> hyper-threaded cores. It lets the h/w know that we aren't
> doing anything useful here, so resources and power can be
> diverted to other threads sharing the core.
>
> Avoiding the need for volatile or other compiler optimizer
> defeating tricks is a side benefit.
Currently it is already that it has to be
while (__raw_spin_is_locked(&v))
cpu_relax();
Just like in __raw_spin_unlock_wait(). Oh well, I should have
checked more before posting...
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