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From: Ingo Molnar <mingo@elte.hu>
To: Eric Dumazet <dada1@cosmosbay.com>
Cc: lkml <linux-kernel@vger.kernel.org>,
	Linus Torvalds <torvalds@osdl.org>, Andrew Morton <akpm@osdl.org>,
	Arjan van de Ven <arjan@infradead.org>,
	Nicolas Pitre <nico@cam.org>,
	Jes Sorensen <jes@trained-monkey.org>,
	Zwane Mwaikambo <zwane@arm.linux.org.uk>,
	Oleg Nesterov <oleg@tv-sign.ru>,
	David Howells <dhowells@redhat.com>,
	Alan Cox <alan@lxorguk.ukuu.org.uk>,
	Benjamin LaHaise <bcrl@kvack.org>,
	Steven Rostedt <rostedt@goodmis.org>,
	Christoph Hellwig <hch@infradead.org>, Andi Kleen <ak@suse.de>,
	Russell King <rmk+lkml@arm.linux.org.uk>
Subject: Re: [patch 04/11] mutex subsystem, add include/asm-x86_64/mutex.h
Date: Tue, 27 Dec 2005 16:41:28 +0100	[thread overview]
Message-ID: <20051227154128.GA15961@elte.hu> (raw)
In-Reply-To: <43B158A6.7080508@cosmosbay.com>


* Eric Dumazet <dada1@cosmosbay.com> wrote:

> >+		:"=D" (dummy)						\
> >+		: "D" (v)						\
> >+		: "rax", "rsi", "rdx", "rcx",				\
> >+		  "r8", "r9", "r10", "r11", "memory");			\
> >+} while (0)
> 
> Hi Ingo
> 
> I do think this assembly is not very fair. It has an *insane* register 
> pressure for the compiler : The fast path is thus not so fast.

if you look at the compiler output you'll notice that it's not a problem 
actually: this fastpath is only inlined into the generic code, where it 
has no clobbering side-effects.

you are right in that if this were to be inlined left and right, this 
would be quite bad.

	Ingo

  reply	other threads:[~2005-12-27 15:42 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2005-12-27 14:15 Ingo Molnar
2005-12-27 15:07 ` Eric Dumazet
2005-12-27 15:41   ` Ingo Molnar [this message]
2005-12-27 17:40   ` Andreas Kleen
  -- strict thread matches above, loose matches on Subject: below --
2005-12-23 16:17 Ingo Molnar

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