Re: [patch][rfc] x86, mutex: non-atomic unlock (and a rant)

From: Cyrill Gorcunov
Date: Mon Nov 02 2009 - 13:10:07 EST

[Cyrill Gorcunov - Mon, Nov 02, 2009 at 07:46:26PM +0300]
| The other option could be that we put two mem-write operations
| like
| int tmp;
| atomic_set(&lock->count, 1);
| tmp = lock->waiters;
| rmb();
| lock->waiters = tmp;
| if (unlikely(lock->waiters))
| fail_fn(lock);
| Which should work faster then cpuid (and we have to be sure somehow
| that gcc doesn't suppress this redundant operations).

And which has nothing to do with OoO mem-read, and wouldn't
work. Sorry for noise.

-- Cyrill
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