From: Nick Piggin <nickpiggin@yahoo.com.au>
To: Andrew Morton <akpm@osdl.org>
Cc: Benjamin LaHaise <bcrl@kvack.org>,
mingo@elte.hu, 76306.1226@compuserve.com,
linux-kernel@vger.kernel.org, torvalds@osdl.org
Subject: Re: [patch] i386 spinlocks: disable interrupts only if we enabled them
Date: Wed, 08 Mar 2006 19:52:17 +1100 [thread overview]
Message-ID: <440E9B41.9020708@yahoo.com.au> (raw)
In-Reply-To: <20060307225556.75cee661.akpm@osdl.org>
Andrew Morton wrote:
> Benjamin LaHaise <bcrl@kvack.org> wrote:
>
>>On Wed, Mar 08, 2006 at 01:43:08AM +0100, Ingo Molnar wrote:
>> > we dont inline that code anymore. So i think the optimization is fine.
>>
>> Why is that? It adds memory traffic that has to be synchronized
>> before the lock occurs and clobbered registers now in the caller.
>
>
> Is the inlined lock;decb+jns likely to worsen the text size? I doubt it.
> Overall text will get bigger due to the out-of-line stuff, but that's OK.
>
> I'm sure we went over all this, but I don't recall the thinking.
Seems like a very good idea not to clobber any registers in
lock fastpaths. I don't see how that could have been a win
(especially for i386) but still, Ingo must have had a reason
behind it.
--
SUSE Labs, Novell Inc.
Send instant messages to your online friends http://au.messenger.yahoo.com
next prev parent reply other threads:[~2006-03-08 8:52 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-03-07 23:34 [patch] i386 spinlocks: disable interrupts only if we enabled them Chuck Ebbert
2006-03-08 0:15 ` Andrew Morton
2006-03-08 0:43 ` Ingo Molnar
2006-03-08 2:52 ` Benjamin LaHaise
2006-03-08 6:55 ` Andrew Morton
2006-03-08 8:52 ` Nick Piggin [this message]
-- strict thread matches above, loose matches on Subject: below --
2006-03-08 1:45 Chuck Ebbert
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