From: Nick Piggin <nickpiggin@yahoo.com.au>
To: Nicolas Pitre <nico@cam.org>
Cc: Linus Torvalds <torvalds@osdl.org>,
Russell King <rmk+lkml@arm.linux.org.uk>,
Ingo Molnar <mingo@elte.hu>,
David Woodhouse <dwmw2@infradead.org>,
Zwane Mwaikambo <zwane@arm.linux.org.uk>,
lkml <linux-kernel@vger.kernel.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@parcelfarce.linux.theplanet.co.uk>,
Oleg Nesterov <oleg@tv-sign.ru>, Paul Jackson <pj@sgi.com>
Subject: Re: [patch 04/15] Generic Mutex Subsystem, add-atomic-call-func-x86_64.patch
Date: Wed, 21 Dec 2005 13:12:23 +1100 [thread overview]
Message-ID: <43A8BA07.4000804@yahoo.com.au> (raw)
In-Reply-To: <Pine.LNX.4.64.0512201533120.26663@localhost.localdomain>
Nicolas Pitre wrote:
> On Tue, 20 Dec 2005, Linus Torvalds wrote:
>>IOW, why don't you just do
>>
>> ldr lr,[%0]
>> subs lr, lr, %1
>> str lr,[%0]
>> blmi failure
>>
>>as the _base_ timings, since that should be the common case. That's the
>>drop-dead fastest UP case.
>
>
> The above is 5 cycles. About the same as the preemption-safe swp-based
> mutex implementation on non-Intel ARM. It is broken wrt interrupts when
> the swp is not.
How it is broken WRT interrupts? (sorry, I haven't had it explained to me
in words of two syllables or less)
--
SUSE Labs, Novell Inc.
Send instant messages to your online friends http://au.messenger.yahoo.com
next prev parent reply other threads:[~2005-12-21 2:12 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-12-19 1:35 [patch 04/15] Generic Mutex Subsystem, add-atomic-call-func-x86_64.patch Ingo Molnar
2005-12-19 17:49 ` Zwane Mwaikambo
2005-12-19 20:58 ` David Woodhouse
2005-12-20 4:31 ` Ingo Molnar
2005-12-20 6:30 ` Nicolas Pitre
2005-12-20 8:12 ` Nick Piggin
2005-12-20 14:10 ` Nicolas Pitre
2005-12-20 14:12 ` Nick Piggin
2005-12-20 14:35 ` Nicolas Pitre
2005-12-20 15:05 ` Nick Piggin
2005-12-20 16:35 ` Nicolas Pitre
2005-12-20 19:20 ` Russell King
2005-12-20 19:32 ` Arjan van de Ven
2005-12-20 19:37 ` Russell King
2005-12-20 19:59 ` Nicolas Pitre
2005-12-20 19:43 ` Steven Rostedt
2005-12-20 19:57 ` Russell King
2005-12-20 20:35 ` Horst von Brand
2005-12-20 19:55 ` Nicolas Pitre
2005-12-20 18:27 ` Linus Torvalds
2005-12-20 19:34 ` Russell King
2005-12-20 20:10 ` Linus Torvalds
2005-12-20 21:18 ` Nicolas Pitre
2005-12-20 22:04 ` Linus Torvalds
2005-12-20 22:19 ` Steven Rostedt
2005-12-20 22:43 ` Nicolas Pitre
2005-12-21 6:00 ` Ingo Molnar
2005-12-21 2:12 ` Nick Piggin [this message]
2005-12-20 19:49 ` Nicolas Pitre
2005-12-20 18:25 ` Linus Torvalds
2005-12-21 6:20 ` Ingo Molnar
2005-12-21 4:16 ` Nicolas Pitre
2005-12-21 6:26 ` Ingo Molnar
2005-12-20 4:29 ` Ingo Molnar
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