Subject: Re: [patch 0/9] mutex subsystem, -V4
From: Xavier Bestel <xavier.bestel@free.fr>
To: Russell King <rmk+lkml@arm.linux.org.uk>
Cc: Andrew Morton <akpm@osdl.org>, Nicolas Pitre <nico@cam.org>,
       hch@infradead.org, alan@lxorguk.ukuu.org.uk, arjan@infradead.org,
       mingo@elte.hu, linux-kernel@vger.kernel.org, torvalds@osdl.org,
       arjanv@infradead.org, jes@trained-monkey.org, zwane@arm.linux.org.uk,
       oleg@tv-sign.ru, dhowells@redhat.com, bcrl@kvack.org,
       rostedt@goodmis.org, ak@suse.de
In-Reply-To: <20051223145746.GA2077@flint.arm.linux.org.uk>
References: <20051222122011.GA20789@elte.hu>
	 <20051222050701.41b308f9.akpm@osdl.org>
	 <1135257829.2940.19.camel@laptopd505.fenrus.org>
	 <20051222054413.c1789c43.akpm@osdl.org>
	 <1135260709.10383.42.camel@localhost.localdomain>
	 <20051222153014.22f07e60.akpm@osdl.org>
	 <20051222233416.GA14182@infradead.org>
	 <20051222221311.2f6056ec.akpm@osdl.org>
	 <Pine.LNX.4.64.0512230912220.26663@localhost.localdomain>
	 <20051223065118.95738acc.akpm@osdl.org>
	 <20051223145746.GA2077@flint.arm.linux.org.uk>
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Date: Fri, 23 Dec 2005 16:04:48 +0100
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On Fri, 2005-12-23 at 15:57, Russell King wrote:
> On Fri, Dec 23, 2005 at 06:51:18AM -0800, Andrew Morton wrote:
> > Nicolas Pitre <nico@cam.org> wrote:
> > > How can't you get the fact that semaphores could _never_ be as simple as 
> > > mutexes?  This is a theoritical impossibility, which maybe turns out not 
> > > to be so true on x86, but which is damn true on ARM where the fast path 
> > > (the common case of a mutex) is significantly more efficient.
> > 
> > I did notice your comments.  I'll grant that mutexes will save some tens of
> > fastpath cycles on one minor architecture.  Sorry, but that doesn't seem
> > very important.
> 
> Wow.

Yes, wow. Andrew doesn't seem aware of embedded linux people, for whom
cycles are important and ARM is king.

	Xav


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