Re: [patch] i386 spinlocks: disable interrupts only if we enabled them

Nick Piggin
2006-03-08T08:52:22Z

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.
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