From: Christoph Hellwig <hch@infradead.org>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Nick Piggin <npiggin@suse.de>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [rfc] "fair" rw spinlocks
Date: Mon, 30 Nov 2009 05:00:41 -0500 [thread overview]
Message-ID: <20091130100041.GA29610@infradead.org> (raw)
In-Reply-To: <alpine.LFD.2.00.0911280927180.2561@localhost>
On Sat, Nov 28, 2009 at 09:30:18AM -0800, Linus Torvalds wrote:
>
>
> On Mon, 23 Nov 2009, Nick Piggin wrote:
> >
> > Last time this issue came up that I could see, I don't think
> > there were objections to making rwlocks fair, the main
> > difficulty seemed to be that we allow reentrant read locks
> > (so a write lock waiting must not block arbitrary read lockers).
>
> We have at least one major rwlock user - tasklist_lock or whatever. And
> that one definitely depends on being able to do 'rwlock()' in an
> interrupt, without other rwlock'ers having to disable irq's (even if there
> might be a new writer coming in on another cpu).
How long will this use be around? I've seen some slow progress toward
replacing most read side uses of the task list lock with RCU. While we
still have lots of read side users now I wonder when they'll go away.
next prev parent reply other threads:[~2009-11-30 10:00 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
2009-11-30 10:00 ` Christoph Hellwig [this message]
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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