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From: Ingo Molnar <mingo@elte.hu>
To: David Howells <dhowells@redhat.com>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>,
	torvalds@osdl.org, akpm@osdl.org, hch@infradead.org,
	arjan@infradead.org, matthew@wil.cx,
	linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org
Subject: Re: [PATCH 1/19] MUTEX: Introduce simple mutex implementation
Date: Tue, 13 Dec 2005 11:13:00 +0100	[thread overview]
Message-ID: <20051213101300.GA2178@elte.hu> (raw)
In-Reply-To: <22479.1134467689@warthog.cambridge.redhat.com>


* David Howells <dhowells@redhat.com> wrote:

> Nick Piggin <nickpiggin@yahoo.com.au> wrote:
> 
> > We have atomic_cmpxchg. Can you use that for a sufficient generic
> > implementation?
> 
> No. CMPXCHG/CAS is not as available as XCHG, and it's also unnecessary.

take a look at the PREEMPT_RT implementation of mutexes: it uses 
cmpxchg(), and thus both the down() and the up() fastpath is lockless!  
(And that is a mutex type that does alot more things, as it supports 
priority inheritance.)

architectures which dont have cmpxchg can use a spinlock just fine.

	Ingo

  reply	other threads:[~2005-12-13 10:13 UTC|newest]

Thread overview: 249+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2005-12-12 23:45 [PATCH 1/19] MUTEX: Introduce simple mutex implementation David Howells
2005-12-12 23:45 ` [PATCH 2/19] MUTEX: i386 arch mutex David Howells
2005-12-12 23:45 ` [PATCH 8/19] MUTEX: Drivers I-K changes David Howells
2005-12-12 23:45 ` [PATCH 7/19] MUTEX: Drivers F-H changes David Howells
2005-12-12 23:45 ` [PATCH 6/19] MUTEX: Drivers A-E changes David Howells
2005-12-12 23:45 ` [PATCH 3/19] MUTEX: x86_64 arch mutex David Howells
2005-12-12 23:45 ` [PATCH 5/19] MUTEX: Core kernel changes David Howells
2005-12-12 23:45 ` [PATCH 4/19] MUTEX: FRV arch mutex David Howells
2005-12-12 23:45 ` [PATCH 15/19] MUTEX: Second set of include changes David Howells
2005-12-12 23:45 ` [PATCH 10/19] MUTEX: Drivers N-P changes David Howells
2005-12-12 23:45 ` [PATCH 9/19] MUTEX: Drivers L-M changes David Howells
2005-12-12 23:45 ` [PATCH 13/19] MUTEX: Filesystem changes David Howells
2005-12-12 23:45 ` [PATCH 14/19] MUTEX: First set of include changes David Howells
2005-12-12 23:45 ` [PATCH 12/19] MUTEX: Drivers T-Z changes David Howells
2005-12-12 23:45 ` [PATCH 11/19] MUTEX: Drivers Q-S changes David Howells
2005-12-12 23:45 ` [PATCH 18/19] MUTEX: Security changes David Howells
2005-12-12 23:45 ` [PATCH 17/19] MUTEX: Networking changes David Howells
2005-12-12 23:45 ` [PATCH 16/19] MUTEX: IPC changes David Howells
2005-12-12 23:45 ` [PATCH 19/19] MUTEX: Sound changes David Howells
2005-12-13  0:13 ` [PATCH 1/19] MUTEX: Introduce simple mutex implementation Nick Piggin
2005-12-13  0:19 ` Nick Piggin
2005-12-13  0:19 ` Andrew Morton
2005-12-13  7:54   ` Ingo Molnar
2005-12-13  7:58     ` Andi Kleen
2005-12-13  8:42       ` Andrew Morton
2005-12-13  8:49         ` Andi Kleen
2005-12-13  9:01           ` Andrew Morton
2005-12-13  9:02             ` Andrew Morton
2005-12-13 10:07               ` Jakub Jelinek
2005-12-13 10:11                 ` Andi Kleen
2005-12-13 10:15                   ` Jakub Jelinek
2005-12-13 10:25                   ` Andrew Morton
2005-12-14 10:46               ` Russell King
2005-12-13  9:05             ` Andi Kleen
2005-12-13  9:15               ` Andrew Morton
2005-12-13  9:24                 ` Andi Kleen
2005-12-13  9:44                   ` Andrew Morton
2005-12-13  9:49                     ` Andi Kleen
2005-12-13 10:28                   ` Andreas Schwab
2005-12-13 10:30                     ` Andi Kleen
2005-12-13 12:33                   ` Matthew Wilcox
2005-12-13 22:18               ` Adrian Bunk
2005-12-13 22:25                 ` Andi Kleen
2005-12-13 22:32                   ` Adrian Bunk
2005-12-13  9:11             ` Ingo Molnar
2005-12-13  9:04           ` Christoph Hellwig
2005-12-13  9:13             ` Ingo Molnar
2005-12-13 10:11             ` Jakub Jelinek
2005-12-13 10:19               ` Christoph Hellwig
2005-12-13 10:27                 ` Ingo Molnar
2005-12-15  4:53                 ` Miles Bader
2005-12-15  5:05                   ` Nick Piggin
2005-12-13  9:09           ` Ingo Molnar
2005-12-13  9:21             ` Andi Kleen
2005-12-13 16:16           ` Linus Torvalds
2005-12-13 21:56             ` Using C99 in the kernel was " Andi Kleen
2005-12-13 23:05               ` Al Viro
2005-12-13 23:41                 ` Andi Kleen
2005-12-13  9:03         ` Christoph Hellwig
2005-12-13  9:14           ` Andrew Morton
2005-12-13  9:21             ` Christoph Hellwig
2005-12-13 10:31             ` drivers/scsi/sd.c gcc-2.95.3 Alexey Dobriyan
2005-12-13  8:00     ` [PATCH 1/19] MUTEX: Introduce simple mutex implementation Arjan van de Ven
2005-12-13  9:03       ` Ingo Molnar
2005-12-13  9:09         ` Andi Kleen
2005-12-13  9:34           ` Ingo Molnar
2005-12-13 14:33             ` Mark Lord
2005-12-13 14:45               ` Arjan van de Ven
2005-12-13  9:37           ` Ingo Molnar
2005-12-13  9:19         ` Arjan van de Ven
2005-12-13  9:02     ` Christoph Hellwig
2005-12-13  9:39       ` Ingo Molnar
2005-12-13 10:00         ` Ingo Molnar
2005-12-13 17:40           ` Paul Jackson
2005-12-13 18:34           ` David Howells
2005-12-13 22:31             ` Paul Jackson
2005-12-14 11:02             ` David Howells
2005-12-14 11:12             ` David Howells
2005-12-14 11:18               ` Alan Cox
2005-12-14 12:35               ` David Howells
2005-12-14 13:58                 ` Thomas Gleixner
2005-12-14 23:40                   ` Mark Lord
2005-12-14 23:54                     ` Andrew Morton
2005-12-15 13:41                       ` Nikita Danilov
2005-12-15 14:56                         ` Alan Cox
2005-12-15 15:52                           ` Nikita Danilov
2005-12-15 16:50                             ` Christopher Friesen
2005-12-15 20:53                               ` Steven Rostedt
2005-12-15 15:55                           ` David Howells
2005-12-15 16:22                             ` linux-os (Dick Johnson)
2005-12-15 16:28                             ` Linus Torvalds
2005-12-15 17:04                               ` Thomas Gleixner
2005-12-15 17:09                               ` Paul Jackson
2005-12-15 17:17                               ` David Howells
2005-12-15 16:51                             ` David Howells
2005-12-15 16:56                             ` Paul Jackson
2005-12-15 17:28                             ` David Howells
2005-12-15 17:48                               ` Linus Torvalds
2005-12-15 18:20                                 ` Nikita Danilov
2005-12-15 20:58                                   ` Steven Rostedt
2005-12-15 19:21                                 ` Andrew Morton
2005-12-15 19:38                                   ` Linus Torvalds
2005-12-15 20:28                                   ` Steven Rostedt
2005-12-15 20:32                                     ` Geert Uytterhoeven
2005-12-16 21:41                                       ` Thomas Gleixner
2005-12-16 21:41                                         ` Linus Torvalds
2005-12-16 22:06                                           ` Thomas Gleixner
2005-12-16 22:19                                             ` Linus Torvalds
2005-12-16 22:32                                               ` Steven Rostedt
2005-12-16 22:42                                               ` Thomas Gleixner
2005-12-16 22:41                                                 ` Linus Torvalds
2005-12-16 22:49                                                   ` Steven Rostedt
2005-12-16 23:29                                                   ` Thomas Gleixner
2005-12-17  0:29                                                   ` Joe Korty
2005-12-17  1:00                                                     ` Linus Torvalds
2005-12-17  3:13                                                       ` Steven Rostedt
2005-12-17  7:34                                                         ` Linus Torvalds
2005-12-17 23:43                                                           ` Matthew Wilcox
2005-12-18  0:05                                                             ` Lee Revell
2005-12-18  0:21                                                               ` Matthew Wilcox
2005-12-18  1:25                                                                 ` Lee Revell
2005-12-22 12:27                                                             ` Bill Huey
2005-12-19 16:08                                                           ` Ingo Molnar
2005-12-22 12:40                                                           ` Bill Huey
2005-12-22 12:45                                                             ` Bill Huey
2005-12-19 23:46                                                       ` Keith Owens
2005-12-15 14:41                       ` Steven Rostedt
2005-12-14 23:57                     ` Thomas Gleixner
2005-12-14 23:57                       ` Mark Lord
2005-12-15  0:10                         ` Thomas Gleixner
2005-12-15  2:46                           ` Linus Torvalds
2005-12-15 15:53                           ` David Howells
2005-12-15 15:37                     ` David Howells
2005-12-15 19:28                       ` Andrew Morton
2005-12-15 20:18                         ` Andrew Morton
2005-12-15 21:28                           ` Steven Rostedt
2005-12-16 22:02                           ` Thomas Gleixner
2005-12-16 10:45                         ` David Howells
2005-12-13  9:55     ` Ingo Molnar
2005-12-13  0:30 ` Arnd Bergmann
2005-12-13  0:57 ` Daniel Walker
2005-12-13  3:23   ` Steven Rostedt
2005-12-13  2:57 ` Mark Lord
2005-12-13  3:17   ` Steven Rostedt
2005-12-13  9:06   ` Christoph Hellwig
2005-12-13  9:54 ` David Howells
2005-12-13 10:13   ` Ingo Molnar [this message]
2005-12-13 10:34     ` Ingo Molnar
2005-12-13 10:37       ` Ingo Molnar
2005-12-13 12:47       ` Oliver Neukum
2005-12-13 13:09         ` Alan Cox
2005-12-13 13:13           ` Matthew Wilcox
2005-12-13 14:04             ` Alan Cox
2005-12-13 13:24           ` Oliver Neukum
2005-12-14  1:00   ` Nick Piggin
2005-12-14 10:54   ` David Howells
2005-12-14 11:17     ` Nick Piggin
2005-12-14 11:46     ` David Howells
2005-12-14 21:23       ` Nick Piggin
2005-12-16 12:00       ` David Howells
2005-12-16 13:16         ` Nick Piggin
2005-12-16 15:53         ` David Howells
2005-12-16 23:41           ` Nick Piggin
2005-12-16 16:02         ` David Howells
2005-12-13 10:48 ` David Howells
2005-12-13 12:39   ` Matthew Wilcox
2005-12-13 10:54 ` Ingo Molnar
2005-12-13 11:23 ` David Howells
2005-12-13 11:24 ` David Howells
2005-12-13 13:45   ` Ingo Molnar
2005-12-13 11:34 ` David Howells
2005-12-13 13:05 ` Alan Cox
2005-12-13 13:15   ` Alan Cox
2005-12-13 23:21     ` Nikita Danilov
2005-12-13 13:32 ` David Howells
2005-12-13 14:00   ` Alan Cox
2005-12-13 14:35   ` Christopher Friesen
2005-12-13 14:44     ` Arjan van de Ven
2005-12-13 14:59       ` Christopher Friesen
2005-12-13 15:23   ` David Howells
2005-12-15  5:24     ` Miles Bader
2005-12-13 15:39   ` David Howells
2005-12-13 16:10     ` Alan Cox
2005-12-14 10:29       ` Arjan van de Ven
2005-12-14 11:03         ` Arjan van de Ven
2005-12-14 11:03         ` Alan Cox
2005-12-14 11:08           ` Arjan van de Ven
2005-12-14 11:24             ` Alan Cox
2005-12-14 11:35               ` Andrew Morton
2005-12-14 11:44                 ` Arjan van de Ven
2005-12-14 11:52                   ` Andi Kleen
2005-12-14 11:55                     ` Arjan van de Ven
2005-12-14 11:57                 ` David Howells
2005-12-14 12:19                   ` Jakub Jelinek
2005-12-16  1:54                   ` Nick Piggin
2005-12-16 11:02                   ` David Howells
2005-12-16 13:01                     ` Nick Piggin
2005-12-16 13:21                       ` Russell King
2005-12-16 13:41                         ` Nick Piggin
2005-12-16 13:46                         ` Linh Dang
2005-12-16 14:31                           ` Russell King
2005-12-16 15:24                             ` Linh Dang
2005-12-16 15:35                               ` Nick Piggin
2005-12-16 15:40                               ` Kyle Moffett
2005-12-16 15:49                             ` Linh Dang
2005-12-16 15:46                           ` David Howells
2005-12-16 15:58                             ` Russell King
2005-12-17 15:57                       ` Nikita Danilov
2005-12-16 16:28                     ` Linus Torvalds
2005-12-16 11:30                   ` David Howells
2005-12-16 16:33                     ` Linus Torvalds
2005-12-16 22:23                       ` David S. Miller
2005-12-16 22:38                         ` Linus Torvalds
2005-12-16 22:53                           ` David S. Miller
2005-12-17  0:41                             ` Jesse Barnes
2005-12-17  7:10                               ` David S. Miller
2005-12-17  7:40                                 ` Linus Torvalds
2005-12-17 17:22                                   ` Jesse Barnes
2005-12-17 17:19                                 ` Jesse Barnes
2005-12-17 22:38                             ` Richard Henderson
2005-12-17 23:05                               ` David S. Miller
2005-12-14 12:17                 ` Christoph Hellwig
2005-12-14 11:42               ` Arjan van de Ven
2005-12-14  8:31     ` Ingo Molnar
2005-12-13 20:04   ` Steven Rostedt
2005-12-13 21:03 ` David Howells
2005-12-15 13:58 linux
2005-12-15 16:15 ` Linus Torvalds
2005-12-15 16:52   ` Erik Mouw
2005-12-15 17:23     ` Dick Streefland
2005-12-16 12:17     ` Erik Mouw
2005-12-17 10:59       ` Sander
2005-12-17 14:14         ` Douglas McNaught
2005-12-17 15:09           ` Sander
2005-12-19 10:44         ` Erik Mouw
2005-12-15 19:02   ` Nikita Danilov
2005-12-15 19:09   ` linux
2005-12-15 19:52     ` Linus Torvalds
2005-12-16  1:33       ` linux
2005-12-15 21:18     ` Steven Rostedt
2005-12-15 20:52   ` Steven Rostedt
2005-12-15 17:45 Luck, Tony
2005-12-15 18:00 ` David Howells
2005-12-15 18:48 ` James Bottomley
2005-12-15 20:38 ` Jeff Dike
2005-12-15 23:45   ` Stephen Rothwell
2005-12-16 12:49 linux
2005-12-16 15:24 ` David Howells
2005-12-16 18:03   ` linux

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