From: Ingo Molnar <mingo@elte.hu>
To: Oleg Nesterov <oleg@tv-sign.ru>
Cc: linux-kernel@vger.kernel.org, Linus Torvalds <torvalds@osdl.org>,
Andrew Morton <akpm@osdl.org>,
Arjan van de Ven <arjanv@infradead.org>,
Steven Rostedt <rostedt@goodmis.org>,
Alan Cox <alan@lxorguk.ukuu.org.uk>,
Christoph Hellwig <hch@infradead.org>, Andi Kleen <ak@suse.de>,
David Howells <dhowells@redhat.com>,
Alexander Viro <viro@ftp.linux.org.uk>, Paul Jackson <pj@sgi.com>
Subject: Re: [patch 05/15] Generic Mutex Subsystem, mutex-core.patch
Date: Wed, 21 Dec 2005 19:26:22 +0100 [thread overview]
Message-ID: <20051221182622.GA8714@elte.hu> (raw)
In-Reply-To: <43A99618.6D6655C6@tv-sign.ru>
* Oleg Nesterov <oleg@tv-sign.ru> wrote:
> But why we can't add the waiter to ->wait_list _after_ xchg() ? What
> makes the difference? Fastpath atomic op can happen before or after
> xchg(), this is ok. Unlock path will look at ->wait_list only after
> taking spinlock, at this time we already added this waiter to the
> ->wait_list.
>
> In other words: we are holding ->wait_lock, nobody can even look at
> ->wait_list. We can add the waiter to ->wait_list before or after
> atomic_xchg() - it does not matter.
hm, you are right - i've added this optimization.
Ingo
next prev parent reply other threads:[~2005-12-21 18:27 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-12-19 1:37 [patch 05/15] Generic Mutex Subsystem, mutex-core.patch Ingo Molnar
2005-12-19 3:56 ` Steven Rostedt
2005-12-19 4:15 ` Steven Rostedt
2005-12-19 4:21 ` Steven Rostedt
2005-12-19 4:43 ` Steven Rostedt
2005-12-19 5:00 ` Steven Rostedt
2005-12-19 5:09 ` Steven Rostedt
2005-12-19 16:51 ` Ingo Molnar
2005-12-19 5:12 ` Steven Rostedt
2005-12-19 16:43 ` Ingo Molnar
2005-12-19 5:16 ` Steven Rostedt
2005-12-21 16:21 ` Oleg Nesterov
2005-12-21 15:57 ` Ingo Molnar
2005-12-21 17:51 ` Oleg Nesterov
2005-12-21 18:26 ` Ingo Molnar [this message]
2005-12-21 15:59 ` Ingo Molnar
2005-12-21 16:02 ` Ingo Molnar
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