From: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
To: Nick Piggin <npiggin@suse.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [rfc] "fair" rw spinlocks
Date: Mon, 30 Nov 2009 08:20:58 -0800 [thread overview]
Message-ID: <20091130162058.GA6762@linux.vnet.ibm.com> (raw)
In-Reply-To: <20091130075557.GI17484@wotan.suse.de>
On Mon, Nov 30, 2009 at 08:55:57AM +0100, Nick Piggin wrote:
> On Sat, Nov 28, 2009 at 09:30:18AM -0800, Linus Torvalds wrote:
> > So as far as I can tell, we have only one real user of rwlocks where
> > livelocks might be relevant, but that one real user absolutely _requires_
> > the unfair behavior.
>
> Yes, although the behaviour required is that it can be recursively
> acquired. So we could still have a lock that disallows new non recursive
> read acquires when there is a pending write locker.
>
> RCU seems nicer, but tasklist lock locking scares me so I wanted to fix
> it the easy way :)
Having a livelock-free tasklist lock would certainly make it easier
to apply things like RCU on a code-path-by-code-path basis as needed.
Much less scary than a big-bang rip-and-replace.
Thanx, Paul
next prev parent reply other threads:[~2009-11-30 16:20 UTC|newest]
Thread overview: 58+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-11-23 14:54 [rfc] "fair" rw spinlocks Nick Piggin
2009-11-24 20:19 ` David Miller
2009-11-25 6:52 ` Nick Piggin
2009-11-25 8:49 ` Andi Kleen
2009-11-25 8:56 ` Nick Piggin
2009-11-24 20:47 ` Andi Kleen
2009-11-25 6:54 ` Nick Piggin
2009-11-25 8:48 ` Andi Kleen
2009-11-25 13:09 ` Arnd Bergmann
2009-11-28 2:07 ` Paul E. McKenney
2009-11-28 11:15 ` Andi Kleen
2009-11-28 15:20 ` Paul E. McKenney
2009-11-28 17:30 ` Linus Torvalds
2009-11-29 18:51 ` Paul E. McKenney
2009-11-30 7:57 ` Nick Piggin
2009-11-30 7:55 ` Nick Piggin
2009-11-30 15:22 ` Linus Torvalds
2009-11-30 15:40 ` Nick Piggin
2009-11-30 16:07 ` Linus Torvalds
2009-11-30 16:17 ` Nick Piggin
2009-11-30 16:39 ` Paul E. McKenney
2009-11-30 17:05 ` Linus Torvalds
2009-11-30 17:13 ` Nick Piggin
2009-11-30 17:18 ` Linus Torvalds
2009-12-01 17:03 ` Arnd Bergmann
2009-12-01 17:15 ` Linus Torvalds
2009-11-30 18:29 ` Paul E. McKenney
2009-11-30 16:20 ` Paul E. McKenney [this message]
2009-11-30 10:00 ` Christoph Hellwig
2009-11-30 15:52 ` Linus Torvalds
2009-11-30 17:46 ` Ingo Molnar
2009-11-30 21:12 ` Thomas Gleixner
2009-11-30 21:27 ` Peter Zijlstra
2009-11-30 22:02 ` Thomas Gleixner
2009-11-30 22:11 ` Linus Torvalds
2009-11-30 22:37 ` Thomas Gleixner
2009-11-30 22:49 ` Linus Torvalds
2009-12-01 17:37 ` [PATCH] audit: Call tty_audit_push_task() outside preempt disabled region Thomas Gleixner
2009-12-01 18:22 ` Oleg Nesterov
2009-12-01 19:53 ` Thomas Gleixner
2009-12-06 3:12 ` [rfc] "fair" rw spinlocks Eric W. Biederman
2009-12-07 18:18 ` Paul E. McKenney
2009-12-07 22:24 ` Eric W. Biederman
2009-12-07 22:35 ` Andi Kleen
2009-12-07 23:19 ` Eric W. Biederman
2009-12-08 1:39 ` Paul E. McKenney
2009-12-08 2:11 ` Eric W. Biederman
2009-12-08 2:37 ` Paul E. McKenney
2009-12-07 18:32 ` Oleg Nesterov
2009-12-07 20:38 ` Peter Zijlstra
2009-12-09 15:55 ` Oleg Nesterov
2009-12-07 22:10 ` Eric W. Biederman
2009-12-09 15:37 ` Oleg Nesterov
2009-12-10 3:36 ` Eric W. Biederman
2009-12-10 6:22 ` Paul E. McKenney
2009-12-10 10:31 ` Eric W. Biederman
2009-12-10 16:41 ` Paul E. McKenney
2009-12-01 19:01 ` Mathieu Desnoyers
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