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Date: Mon, 2 Jan 2006 18:03:26 +0100
From: Ingo Molnar <mingo@elte.hu>
To: Andi Kleen <ak@suse.de>
Cc: lkml <linux-kernel@vger.kernel.org>, Linus Torvalds <torvalds@osdl.org>,
       Andrew Morton <akpm@osdl.org>, Arjan van de Ven <arjan@infradead.org>,
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       Alan Cox <alan@lxorguk.ukuu.org.uk>,
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       Russell King <rmk+lkml@arm.linux.org.uk>
Subject: Re: [patch 05/19] mutex subsystem, add include/asm-x86_64/mutex.h
Message-ID: <20060102170326.GA5593@elte.hu>
References: <20060102163354.GF31501@elte.hu> <20060102164605.GB7222@wotan.suse.de>
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* Andi Kleen <ak@suse.de> wrote:

> > +		: "rax", "rsi", "rdx", "rcx",				\
> > +		  "r8", "r9", "r10", "r11", "memory");			\
> 
> I think it would be still better if you used the stubs in 
> arch/x86_64/lib/thunk.S and not clobber all the registers. While it 
> won't make that much difference for the out of line mutexes it will 
> generate better code for inline mutexes, and if someone ever decides 
> they're a good idea the code will be ready.

i didnt want to add it to thunk.S because right now it would cause an 
unnecessary slowdown for the slowpath, by quite a number of 
instructions: due to the indiscriminate register-saving/restoring done 
in thunk.S.

even though it's a "slow path" relative to the fastpath, we shouldnt 
slow it down unnecessarily. So if someone wants to play with more 
inlining later on, this has to be done in context of that effort.

	Ingo