Re: [PATCH] Re: futex and timeouts

H. Peter Anvin (hpa@zytor.com)
14 Mar 2002 22:56:09 -0800


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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