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To: linux-kernel@vger.kernel.org
From: "H. Peter Anvin" <hpa@zytor.com>
Subject: Re: [PATCH] Re: futex and timeouts
Date: 14 Mar 2002 22:56:09 -0800
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In-Reply-To: <20020314151846.EDCBF3FE07@smtp.linux.ibm.com> <E16lkRS-0001HN-00@wagner.rustcorp.com.au> <20020315060829.L4836@parcelfarce.linux.theplanet.co.uk>
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Copyright: Copyright 2002 H. Peter Anvin - All Rights Reserved
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Followup to:  <20020315060829.L4836@parcelfarce.linux.theplanet.co.uk>
By author:    Joel Becker <jlbec@evilplan.org>
In newsgroup: linux.dev.kernel
>
> On Fri, Mar 15, 2002 at 04:39:50PM +1100, Rusty Russell wrote:
> > Yep, sorry, my mistake.  I suggest make it a relative "struct timespec
> > *" (more futureproof that timeval).  It would make sense to split the
> > interface into futex_down and futex_up syuscalls, since futex_up
> > doesn't need a timeout arg, but I haven't for the moment.
> 
> 	Why waste a syscall?  The user is going to be using a library
> wrapper.  They don't have to know that futex_up() calls sys_futex(futex,
> FUTEX_UP, NULL);
> 

Syscalls are (by and large) cheap.  Extra dispatches, however, hurt.

	-hpa
-- 
<hpa@transmeta.com> at work, <hpa@zytor.com> in private!
"Unix gives you enough rope to shoot yourself in the foot."
http://www.zytor.com/~hpa/puzzle.txt	<amsp@zytor.com>
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