On Wed, Sep 07, 2005 at 03:49:37PM +1000, Paul Mackerras wrote:
> Maybe, but it seems like a bad idea to me. It's longer, it's less
> obvious what's happening,
I would argue it more obvious. People looking at the code
are immediately going to realize it was a deliberate choice to
not use a spinlock.
> and it precludes the sorts of optimization
> that we do on ppc64 where a cpu that is waiting for a lock can tell
> give its time slice to the cpu that is holding the lock (on systems
> where the hypervisor time-slices multiple virtual cpus on one physical
> cpu).
relax_cpu() doesn't do that?
> What's wrong with just doing spin_lock/spin_unlock?
it's not wrong - just misleading IMHO. There is no
"critical section" in that particular chunk of code.
If relax_cpu doesn't allow time-slice donation, then I guess
spinlock/unlock with only a comment inside it explain why
would be ok too.
thanks,
grant
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