From: Cyrill Gorcunov <gorcunov@gmail.com>
To: Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
Nick Piggin <npiggin@suse.de>, Ingo Molnar <mingo@elte.hu>
Subject: Re: [patch][rfc] x86, mutex: non-atomic unlock (and a rant)
Date: Mon, 2 Nov 2009 21:09:59 +0300 [thread overview]
Message-ID: <20091102180959.GC10072@lenovo> (raw)
In-Reply-To: <20091102164626.GA10072@lenovo>
[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
prev parent reply other threads:[~2009-11-02 18:09 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-11-02 12:07 [patch][rfc] x86, mutex: non-atomic unlock (and a rant) Nick Piggin
2009-11-02 15:20 ` Linus Torvalds
2009-11-02 16:00 ` Nick Piggin
2009-11-02 16:46 ` Cyrill Gorcunov
2009-11-02 18:09 ` Cyrill Gorcunov [this message]
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