From: Ingo Molnar <mingo@elte.hu>
To: Nicolas Pitre <nico@cam.org>
Cc: Christoph Hellwig <hch@infradead.org>,
lkml <linux-kernel@vger.kernel.org>,
Linus Torvalds <torvalds@osdl.org>, Andrew Morton <akpm@osdl.org>,
Arjan van de Ven <arjanv@infradead.org>,
Jes Sorensen <jes@trained-monkey.org>,
Zwane Mwaikambo <zwane@arm.linux.org.uk>,
Oleg Nesterov <oleg@tv-sign.ru>,
David Howells <dhowells@redhat.com>,
Alan Cox <alan@lxorguk.ukuu.org.uk>,
Benjamin LaHaise <bcrl@kvack.org>,
Steven Rostedt <rostedt@goodmis.org>, Andi Kleen <ak@suse.de>
Subject: Re: [patch 0/9] mutex subsystem, -V4
Date: Thu, 22 Dec 2005 22:54:30 +0100 [thread overview]
Message-ID: <20051222215430.GA7506@elte.hu> (raw)
In-Reply-To: <Pine.LNX.4.64.0512221613010.26663@localhost.localdomain>
* Nicolas Pitre <nico@cam.org> wrote:
> I'd like to point out that, while atomic_dec_call_if_* is really nice
> on i386, it is probably only good for i386 since no other architecture
> will be able to provide a better implementation than what can be done
> with atomic_dec_return() anyway. Yet that IMHO overloaded
> atomic_dec_call_if_* stuff appears in core code.
i'd have no problem with going to atomic_dec_return() on i386 too.
atomic_dec_call_if_*() is just working around a gcc limitation: there's
no way to pass a condition from inline assembly into C code, it has to
go over a register. But the difference is small, just 1 extra 'sete'
instruction. So x86 would be just fine with atomic_dec_return() too.
anyway, it seems like everyone would like to hack a few instructions
from the fastpath, so we might as well go with your approach. As long as
the state is well-defined (and it has to be well-defined because it all
hits the common slowpath), and the function names are descriptive of
what happens, it's fine with me.
Ingo
next prev parent reply other threads:[~2005-12-22 21:55 UTC|newest]
Thread overview: 62+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-12-22 11:41 [patch 0/9] mutex subsystem, -V4 Ingo Molnar
2005-12-22 11:53 ` Christoph Hellwig
2005-12-22 12:45 ` Ingo Molnar
2005-12-22 15:34 ` Nicolas Pitre
2005-12-22 15:40 ` Ingo Molnar
2005-12-22 16:32 ` Nicolas Pitre
2005-12-22 16:44 ` Ingo Molnar
2005-12-22 16:58 ` Russell King
2005-12-22 21:04 ` Ingo Molnar
2005-12-22 21:26 ` Russell King
2005-12-22 21:27 ` Nicolas Pitre
2005-12-22 21:37 ` [patch 1/2] mutex subsystem: basic per arch fast path primitives Nicolas Pitre
2005-12-22 21:53 ` Christoph Hellwig
2005-12-22 21:40 ` [patch 2/2] mutex subsystem: use the per architecture fast path lock_unlock defines Nicolas Pitre
2005-12-22 21:54 ` Ingo Molnar [this message]
2005-12-22 16:58 ` [patch 0/9] mutex subsystem, -V4 Nicolas Pitre
2005-12-22 17:20 ` Christoph Hellwig
2005-12-22 17:33 ` Steven Rostedt
2005-12-22 18:24 ` Nicolas Pitre
2005-12-22 11:54 ` Andrew Morton
2005-12-22 12:20 ` Ingo Molnar
2005-12-22 13:07 ` Andrew Morton
2005-12-22 13:23 ` Arjan van de Ven
2005-12-22 13:44 ` Andrew Morton
2005-12-22 14:11 ` Alan Cox
2005-12-22 23:30 ` Andrew Morton
2005-12-22 23:34 ` Christoph Hellwig
2005-12-22 23:49 ` Sean
2005-12-22 23:49 ` Sean
2005-12-22 23:53 ` Randy.Dunlap
2005-12-23 0:00 ` Sean
2005-12-23 0:00 ` Sean
2005-12-23 0:00 ` Steven Rostedt
[not found] ` <20051222221311.2f6056ec.akpm@osdl.org>
2005-12-23 14:24 ` Nicolas Pitre
2005-12-23 14:51 ` Andrew Morton
2005-12-23 14:57 ` Russell King
2005-12-23 15:04 ` Xavier Bestel
2005-12-23 15:27 ` Andrew Morton
2005-12-23 15:00 ` Steven Rostedt
2006-01-03 17:54 ` Abhijit Bhopatkar
2005-12-25 16:08 ` Roman Zippel
2005-12-25 22:54 ` Ingo Molnar
2005-12-26 21:49 ` Roman Zippel
2005-12-25 23:04 ` Andrew Morton
2005-12-25 23:22 ` Ingo Molnar
2005-12-26 10:35 ` Andrew Morton
2005-12-26 10:42 ` Arjan van de Ven
2005-12-26 11:11 ` Andrew Morton
2005-12-26 17:15 ` Mike Galbraith
2005-12-26 17:44 ` Lee Revell
2005-12-27 0:32 ` David Lang
2005-12-26 18:15 ` Linus Torvalds
2005-12-27 14:42 ` Ingo Molnar
2005-12-27 23:02 ` Andrew Morton
2005-12-26 0:33 ` Moore's law (was Re: [patch 0/9] mutex subsystem, -V4) Pavel Machek
2006-01-05 15:30 ` Andi Kleen
2006-01-05 19:08 ` Pavel Machek
2005-12-26 15:29 ` [patch 0/9] mutex subsystem, -V4 Nicolas Pitre
2005-12-22 15:46 ` Thomas Gleixner
2005-12-22 17:40 ` Linus Torvalds
2005-12-22 20:09 ` Steven Rostedt
2005-12-22 17:17 ` Christoph Hellwig
2005-12-22 15:19 ` Nicolas Pitre
2005-12-22 21:43 ` Paul Mackerras
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