From: Rusty Russell <rusty@rustcorp.com.au>
To: Benjamin LaHaise <bcrl@redhat.com>
Cc: alan@lxorguk.ukuu.org.uk, torvalds@transmeta.com, mingo@elte.hu,
matthew@hairy.beasts.org, david@mysql.com, wli@holomorphy.com,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH] Lightweight userspace semaphores...
Date: Sun, 3 Mar 2002 18:07:21 +1100 [thread overview]
Message-ID: <20020303180721.57f36b07.rusty@rustcorp.com.au> (raw)
In-Reply-To: <20020225113239.A11675@redhat.com>
In-Reply-To: <Pine.LNX.4.33.0202250808150.3268-100000@home.transmeta.com> <E16fOAO-0005Ml-00@the-village.bc.nu> <20020225113239.A11675@redhat.com>
On Mon, 25 Feb 2002 11:32:40 -0500
Benjamin LaHaise <bcrl@redhat.com> wrote:
> On Mon, Feb 25, 2002 at 04:39:56PM +0000, Alan Cox wrote:
> > _alloca
> > mmap
> >
> > Still fits on the stack 8)
>
> Are we sure that forcing semaphore overhead to the size of a page is a
> good idea? I'd much rather see a sleep/wakeup mechanism akin to wait
> queues be exported by the kernel so that userspace can implement a rich
> set of locking functions on top of that in whatever shared memory is
> being used.
Unfortunately, no. You need to know what userspace is using them for so
you can check to avoid the "add to waitqueue" race.
AFAICT a mutex is the simplest useful primitive that can be realistically
exported.
Hope that helps,
Rusty.
--
Anyone who quotes me in their sig is an idiot. -- Rusty Russell.
next prev parent reply other threads:[~2002-03-04 4:15 UTC|newest]
Thread overview: 47+ messages / expand[flat|nested] mbox.gz Atom feed top
2002-02-23 3:47 [PATCH] Lightweight userspace semaphores Rusty Russell
2002-02-23 15:03 ` Ingo Molnar
2002-02-23 18:20 ` Linus Torvalds
2002-02-23 18:28 ` Larry McVoy
2002-02-23 20:31 ` Ingo Molnar
2002-02-23 21:22 ` Alan Cox
2002-02-26 16:09 ` Hubertus Franke
2002-02-24 23:29 ` Rusty Russell
2002-02-24 23:48 ` Linus Torvalds
2002-02-25 1:10 ` Rusty Russell
2002-02-25 1:23 ` Linus Torvalds
2002-02-25 13:14 ` Alan Cox
2002-02-25 16:11 ` Linus Torvalds
2002-02-25 16:39 ` Alan Cox
2002-02-25 16:32 ` Benjamin LaHaise
2002-02-25 17:42 ` Alan Cox
2002-02-25 18:23 ` Hubertus Franke
2002-02-25 20:57 ` Hubertus Franke
2002-03-03 7:07 ` Rusty Russell [this message]
2002-02-25 17:06 ` Linus Torvalds
2002-02-25 17:31 ` Alan Cox
2002-02-25 17:20 ` Linus Torvalds
2002-02-25 17:50 ` Alan Cox
2002-02-25 17:44 ` Linus Torvalds
2002-02-25 18:06 ` Alan Cox
2002-02-25 19:31 ` Linus Torvalds
2002-02-24 4:57 ` Daniel Phillips
2002-02-25 19:51 ` Hubertus Franke
2002-02-26 12:15 ` [PATCH] 2.5.5 IDE clean 14 Martin Dalecki
2002-02-26 21:49 ` Keith Owens
2002-02-27 10:08 ` Martin Dalecki
2002-03-01 4:56 ` [PATCH] Lightweight userspace semaphores Eric W. Biederman
2002-03-02 14:54 ` Pavel Machek
2002-02-25 15:00 ` Hubertus Franke
2002-02-27 0:24 ` Rusty Russell
2002-02-27 15:53 ` Hubertus Franke
2002-03-01 0:24 ` Richard Henderson
2002-03-01 2:00 ` Hubertus Franke
2002-02-27 16:29 ` Hubertus Franke
2002-03-02 14:50 ` Hubertus Franke
2002-03-03 13:30 ` Rusty Russell
2002-03-04 16:51 ` Hubertus Franke
2002-03-05 4:41 ` Rusty Russell
2002-03-01 4:44 ` Eric W. Biederman
-- strict thread matches above, loose matches on Subject: below --
2002-02-27 8:43 [PATCH] Lightweight userspace semphores Martin Wirth
2002-02-27 15:24 ` Hubertus Franke
2002-02-27 17:17 ` Martin Wirth
2002-02-27 19:04 ` Hubertus Franke
[not found] ` <3C7FDF76.9040903@dlr.de>
2002-03-02 14:08 ` [PATCH] Lightweight userspace semaphores Hubertus Franke
[not found] <20020227163834.GF322@reload.nmd.msu.ru>
2002-02-27 16:58 ` Hubertus Franke
[not found] ` <20020227173307.GH322@reload.nmd.msu.ru>
2002-02-27 22:09 ` Hubertus Franke
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