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From: Andrew Morton <andrewm@uow.edu.au>
To: yodaiken@fsmlabs.com
Cc: Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: rw_semaphores
Date: Mon, 16 Apr 2001 10:26:16 -0700	[thread overview]
Message-ID: <3ADB2B38.90EBF599@uow.edu.au> (raw)
In-Reply-To: <Pine.LNX.4.31.0104092242320.11520-100000@penguin.transmeta.com> <8623.986888854@warthog.cambridge.redhat.com>, <8623.986888854@warthog.cambridge.redhat.com>; from dhowells@cambridge.redhat.com on Tue, Apr 10, 2001 at 08:47:34AM +0100 <20010416083912.C4036@hq.fsmlabs.com>

yodaiken@fsmlabs.com wrote:
> 
> On Tue, Apr 10, 2001 at 08:47:34AM +0100, David Howells wrote:
> >
> > Since you're willing to use CMPXCHG in your suggested implementation, would it
> > make it make life easier if you were willing to use XADD too?
> >
> > Plus, are you really willing to limit the number of readers or writers to be
> > 32767? If so, I think I can suggest a way that limits it to ~65535 apiece
> > instead...
> 
> I'm trying to imagine a case where 32,000 sharing a semaphore was anything but a
> major failure and I can't. To me: the result of an attempt by the 32,768th locker
> should be a kernel panic. Is there a reasonable scenario where this is wrong?
> 

It can't happen (famous last words).

- It is a bug for a task to acquire an rwsem more than once
  (either for read or write), so we don't do this.

- Linux only supports, err, 31700 user processes.

  parent reply	other threads:[~2001-04-16 17:31 UTC|newest]

Thread overview: 50+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <3AD0FD0F.9B0C47FD@uow.edu.au>
2001-04-09  3:08 ` rw_semaphores Linus Torvalds
2001-04-09  4:18   ` rw_semaphores Linus Torvalds
2001-04-09 13:55     ` rw_semaphores Ben LaHaise
2001-04-10  2:41 ` rw_semaphores Tachino Nobuhiro
2001-04-10  5:43   ` rw_semaphores Linus Torvalds
2001-04-10  7:47     ` rw_semaphores David Howells
2001-04-10 18:02       ` [PATCH] i386 rw_semaphores fix David Howells
2001-04-10 19:42         ` Linus Torvalds
2001-04-10 19:56           ` x86 cpu configuration (was: Re: [PATCH] i386 rw_semaphores fix) Jeff Garzik
2001-04-10 21:58             ` Alan Cox
2001-04-10 20:05           ` [PATCH] i386 rw_semaphores fix Andi Kleen
2001-04-10 20:16             ` Linus Torvalds
2001-04-10 22:00             ` Alan Cox
2001-04-11  0:00               ` Andi Kleen
2001-04-11  0:13                 ` David Weinehall
2001-04-11  0:20                   ` Andi Kleen
2001-04-11  0:56                     ` David Weinehall
2001-04-11  1:04                       ` Andi Kleen
2001-04-11 12:32                     ` Alan Cox
2001-04-11  0:55                   ` Linus Torvalds
2001-04-11  1:07                     ` Andi Kleen
2001-04-11  1:12                       ` Linus Torvalds
2001-04-11  1:23                         ` Andi Kleen
2001-04-11 12:36                           ` Alan Cox
2001-04-11 18:05                     ` H. Peter Anvin
2001-04-11 12:28                 ` Alan Cox
2001-04-11 18:06                   ` H. Peter Anvin
2001-04-11 22:06                     ` Alan Cox
2001-04-11 22:42                       ` H. Peter Anvin
2001-04-11 22:55                         ` Alan Cox
2001-04-10 21:57           ` Alan Cox
2001-04-11  0:40             ` Tim Wright
2001-04-11  7:38           ` David Howells
2001-04-11 12:24             ` Maciej W. Rozycki
2001-04-11 12:57           ` [PATCH] 2nd try: " David Howells
2001-04-11 16:37             ` [PATCH] 3rd " David Howells
2001-04-11 21:41               ` [PATCH] 4th " David Howells
2001-04-12 18:16                 ` Andrew Morton
2001-04-11 23:00               ` [PATCH] 3rd " Anton Blanchard
2001-04-12 15:06                 ` [PATCH] i386 rw_semaphores, general abstraction patch David Howells
2001-04-11 16:56         ` [PATCH] i386 rw_semaphores fix Andrew Morton
2001-04-11 17:36           ` David Howells
2001-04-11 18:41             ` Linus Torvalds
2001-04-11 21:27           ` David Howells
2001-04-16 14:39       ` rw_semaphores yodaiken
2001-04-16 14:56         ` rw_semaphores Alan Cox
2001-04-16 17:05         ` rw_semaphores Linus Torvalds
2001-04-16 17:34           ` rw_semaphores yodaiken
2001-04-16 17:26         ` Andrew Morton [this message]
2001-04-10  6:33   ` rw_semaphores Tachino Nobuhiro

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