From: Nick Piggin <npiggin@suse.de>
To: Ingo Molnar <mingo@elte.hu>
Cc: Andi Kleen <ak@suse.de>,
Linus Torvalds <torvalds@linux-foundation.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [rfc][patch 2/2] x86_64: FIFO ticket spinlocks
Date: Mon, 16 Jul 2007 11:45:03 +0200 [thread overview]
Message-ID: <20070716094503.GC21464@wotan.suse.de> (raw)
In-Reply-To: <20070716092646.GA18423@elte.hu>
On Mon, Jul 16, 2007 at 11:26:46AM +0200, Ingo Molnar wrote:
>
> * Nick Piggin <npiggin@suse.de> wrote:
>
> > [...] trylock is more significantly slower, but they are relatively
> > rare.
>
> trylock is the main thing that the spinlock debugging code uses, and
> SPINLOCK_DEBUG is frequently enabled by distro kernels. OTOH, the cost
> looks like to be +5 instructions, right? Still ...
Which trylocks do you mean? The lockbreak spinlocks use trylock, but
those are not used with the ticket version.
I wouldn't be against adding an option between either of the lock
types, if there was value in it. But I would like to default ticket
locks to "y", at least in -rc kernels, in order to see if performance
goes down anywhere.
next prev parent reply other threads:[~2007-07-16 9:45 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-07-16 4:59 [rfc][patch 1/2] spinlock: lockbreak cleanups Nick Piggin
2007-07-16 5:01 ` [rfc][patch 2/2] x86_64: FIFO ticket spinlocks Nick Piggin
2007-07-16 9:16 ` Alan Cox
2007-07-16 9:24 ` Nick Piggin
2007-07-16 9:26 ` Ingo Molnar
2007-07-16 9:45 ` Nick Piggin [this message]
2007-07-16 9:49 ` Ingo Molnar
2007-07-16 10:18 ` Nick Piggin
2007-07-17 14:25 ` Andi Kleen
2007-07-17 15:08 ` Nick Piggin
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