From: Linus Torvalds <torvalds@linux-foundation.org>
To: Ingo Molnar <mingo@elte.hu>
Cc: Matthew Wilcox <matthew@wil.cx>,
Peter Zijlstra <a.p.zijlstra@chello.nl>,
"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
Gregory Haskins <ghaskins@novell.com>,
Andi Kleen <andi@firstfloor.org>,
Chris Mason <chris.mason@oracle.com>,
Andrew Morton <akpm@linux-foundation.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
linux-fsdevel <linux-fsdevel@vger.kernel.org>,
linux-btrfs <linux-btrfs@vger.kernel.org>,
Thomas Gleixner <tglx@linutronix.de>,
Nick Piggin <npiggin@suse.de>,
Peter Morreale <pmorreale@novell.com>,
Sven Dietrich <SDietrich@novell.com>,
Dmitry Adamushko <dmitry.adamushko@gmail.com>,
Johannes Weiner <hannes@cmpxchg.org>
Subject: Re: [GIT PULL] adaptive spinning mutexes
Date: Thu, 15 Jan 2009 10:16:53 -0800 (PST) [thread overview]
Message-ID: <alpine.LFD.2.00.0901151015270.6528@localhost.localdomain> (raw)
In-Reply-To: <20090115180844.GL22472@elte.hu>
On Thu, 15 Jan 2009, Ingo Molnar wrote:
>
> btw., i think spin-mutexes have a design advantage here: in a lot of code
> areas it's quite difficult to use spinlocks - cannot allocate memory,
> cannot call any code that can sporadically block (but does not _normally_
> block), etc.
>
> With mutexes those atomicity constraints go away - and the performance
> profile should now be quite close to that of spinlocks as well.
Umm. Except if you wrote the code nicely and used spinlocks, you wouldn't
hold the lock over all those unnecessary and complex operations.
IOW, if you do pre-allocation instead of holding a lock over the
allocation, you win. So yes, spin-mutexes makes it easier to write the
code, but it also makes it easier to just plain be lazy.
Linus
next prev parent reply other threads:[~2009-01-15 18:16 UTC|newest]
Thread overview: 92+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-01-12 15:37 [PATCH -v8][RFC] mutex: implement adaptive spinning Peter Zijlstra
2009-01-12 16:04 ` Linus Torvalds
2009-01-12 16:20 ` Linus Torvalds
2009-01-12 16:45 ` Chris Mason
2009-01-12 16:50 ` Peter Zijlstra
2009-01-12 17:14 ` Chris Mason
2009-01-12 17:24 ` Peter Zijlstra
2009-01-12 17:30 ` Chris Mason
2009-01-12 17:16 ` Peter Zijlstra
2009-01-12 17:33 ` Boaz Harrosh
2009-01-12 18:07 ` Peter Zijlstra
2009-01-12 16:13 ` Avi Kivity
2009-01-12 17:13 ` Peter Zijlstra
2009-01-12 17:23 ` Avi Kivity
2009-01-12 17:32 ` Avi Kivity
2009-01-14 16:46 ` Peter Zijlstra
2009-01-14 17:04 ` Nick Piggin
2009-01-14 17:23 ` Avi Kivity
2009-01-15 0:50 ` Nick Piggin
2009-01-13 15:15 ` [PATCH -v9][RFC] " Peter Zijlstra
2009-01-13 16:16 ` Linus Torvalds
2009-01-13 16:21 ` Peter Zijlstra
2009-01-13 16:39 ` Ingo Molnar
2009-01-13 16:40 ` Peter Zijlstra
2009-01-13 16:49 ` Linus Torvalds
2009-01-13 17:21 ` Peter Zijlstra
2009-01-13 18:33 ` Ingo Molnar
2009-01-13 18:40 ` Linus Torvalds
2009-01-13 19:01 ` Ingo Molnar
2009-01-14 2:58 ` Chris Mason
2009-01-14 11:18 ` Dmitry Adamushko
2009-01-14 16:47 ` Chris Mason
2009-01-14 17:32 ` Dmitry Adamushko
2009-01-14 11:21 ` Ingo Molnar
2009-01-14 15:43 ` Linus Torvalds
2009-01-14 16:23 ` Chris Mason
2009-01-14 17:06 ` [PATCH -v11 delta] " Ingo Molnar
2009-01-14 17:00 ` [PATCH -v11][RFC] " Peter Zijlstra
2009-01-14 17:18 ` Nick Piggin
2009-01-14 17:22 ` Peter Zijlstra
2009-01-15 0:46 ` Nick Piggin
2009-01-15 7:44 ` Peter Zijlstra
2009-01-15 7:52 ` Nick Piggin
2009-01-14 18:33 ` [GIT PULL] adaptive spinning mutexes Ingo Molnar
2009-01-14 18:40 ` Chris Mason
2009-01-15 9:53 ` Ingo Molnar
2009-01-14 18:47 ` Ingo Molnar
2009-01-14 19:28 ` Ingo Molnar
2009-01-15 17:44 ` Matthew Wilcox
2009-01-15 18:05 ` Linus Torvalds
2009-01-15 18:08 ` Ingo Molnar
2009-01-15 18:16 ` Linus Torvalds [this message]
2009-01-15 19:26 ` Chris Mason
2009-01-15 20:13 ` Linus Torvalds
2009-01-15 21:04 ` Chris Mason
2009-01-15 22:03 ` Ingo Molnar
2009-01-16 13:32 ` Folkert van Heusden
2009-01-16 13:57 ` Folkert van Heusden
2009-01-16 18:37 ` Bill Davidsen
2009-01-16 0:53 ` Paul E. McKenney
2009-01-16 1:01 ` Linus Torvalds
2009-01-16 1:34 ` Paul E. McKenney
2009-01-16 14:07 ` Folkert van Heusden
2009-01-16 3:03 ` Nick Piggin
2009-01-15 18:06 ` Ingo Molnar
2009-01-14 18:53 ` Andrew Morton
2009-01-14 19:00 ` Ingo Molnar
2009-01-14 19:36 ` Andrew Morton
2009-01-14 19:50 ` Peter Zijlstra
2009-01-14 20:21 ` Andrew Morton
2009-01-14 20:27 ` Ingo Molnar
2009-01-14 20:44 ` Andrew Morton
2009-01-14 20:14 ` Ingo Molnar
2009-01-14 20:30 ` Andrew Morton
2009-01-14 20:51 ` Ingo Molnar
2009-01-14 21:06 ` Andrew Morton
2009-01-14 21:14 ` Ingo Molnar
2009-01-14 21:35 ` Andrew Morton
2009-01-14 23:23 ` Ingo Molnar
2009-01-15 0:55 ` Nick Piggin
2009-01-14 21:41 ` Ingo Molnar
2009-01-14 21:50 ` Kay Sievers
2009-01-14 22:34 ` Ingo Molnar
2009-01-15 11:45 ` Folkert van Heusden
2009-01-15 12:53 ` Chris Samuel
2009-01-14 19:23 ` Peter Zijlstra
2009-01-14 19:33 ` Ingo Molnar
2009-01-15 8:41 ` [PATCH] mutex: set owner only once on acquisition Johannes Weiner
2009-01-15 8:56 ` Johannes Weiner
2009-01-13 18:12 ` [PATCH -v9][RFC] mutex: implement adaptive spinning Ingo Molnar
2009-01-13 18:21 ` Linus Torvalds
2009-01-13 18:24 ` Ingo Molnar
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