From: Thomas Gleixner <tglx@linutronix.de>
To: Andrew Morton <akpm@osdl.org>
Cc: Arjan van de Ven <arjan@infradead.org>,
mingo@elte.hu, linux-kernel@vger.kernel.org, torvalds@osdl.org,
arjanv@infradead.org, nico@cam.org, jes@trained-monkey.org,
zwane@arm.linux.org.uk, oleg@tv-sign.ru, dhowells@redhat.com,
alan@lxorguk.ukuu.org.uk, bcrl@kvack.org, rostedt@goodmis.org,
hch@infradead.org, ak@suse.de, rmk+lkml@arm.linux.org.uk
Subject: Re: [patch 0/9] mutex subsystem, -V4
Date: Thu, 22 Dec 2005 16:46:09 +0100 [thread overview]
Message-ID: <1135266369.2806.212.camel@tglx.tec.linutronix.de> (raw)
In-Reply-To: <20051222054413.c1789c43.akpm@osdl.org>
On Thu, 2005-12-22 at 05:44 -0800, Andrew Morton wrote:
> There's no need for two sets of behaviour. What I'm saying is that we
> could add similar debugging features to semaphores (if useful). Yes, we
> would have to tell the kernel at the source level to defeat that debugging
> if a particular lock isn't being used as a mutex. That's rather less
> intrusive than adding a whole new type of lock. But I'd question the value
> even of doing that, given the general historical non-bugginess of existing
> semaphore users.
Semaphores need a counter, mutexes only a binary representation of the
locked/unlocked state, which makes it possible to use instructions like
xchg, swap, test_and_set_bit depending on what atomic operations are
available on the architecture. On many architectures this is more
efficient than the counter based implementation.
Also the wakeup rules allow smaller and faster implementations for
mutexes.
tglx
next prev parent reply other threads:[~2005-12-22 15:39 UTC|newest]
Thread overview: 62+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-12-22 11:41 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 ` [patch 0/9] mutex subsystem, -V4 Ingo Molnar
2005-12-22 16:58 ` 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
[not found] ` <32801.10.10.10.28.1135295357.squirrel@linux1>
2005-12-22 23:49 ` Sean
2005-12-22 23:53 ` Randy.Dunlap
[not found] ` <50572.10.10.10.28.1135296023.squirrel@linux1>
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 [this message]
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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