From: Jeremy Fitzhardinge <jeremy@goop.org>
To: Nick Piggin <nickpiggin@yahoo.com.au>
Cc: Rik van Riel <riel@redhat.com>,
Peter Zijlstra <a.p.zijlstra@chello.nl>,
Christoph Lameter <clameter@sgi.com>,
Petr Tesarik <ptesarik@suse.cz>, Ingo Molnar <mingo@elte.hu>,
linux-kernel@vger.kernel.org
Subject: Re: Spinlocks: Factor our GENERIC_LOCKBREAK in order to avoid spin with irqs disable
Date: Tue, 08 Jul 2008 08:58:36 -0700 [thread overview]
Message-ID: <48738EAC.6090707@goop.org> (raw)
In-Reply-To: <200807081841.50422.nickpiggin@yahoo.com.au>
Nick Piggin wrote:
> Sure. Btw. I have no problems with your patchset, but if SMP guests
> are seriously used on x86, just remember the fairness issue. At some
> point you might find you'll need an even more advanced lock for Xen.
>
Perhaps. The spin lock has a bounded number of iterations before it
goes into the vcpu-blocking path. At that point, it's no longer subject
to the whims of the cache coherency protocol, and is explicitly woken.
But it may still have issues when competing with a rapid lock-unlocker.
A ticket-lock variant with some kind of directed yield might be the way
to go if it turns out to be a problem.
J
next prev parent reply other threads:[~2008-07-08 15:58 UTC|newest]
Thread overview: 35+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-05-06 19:26 Spinlocks waiting with interrupts disabled / preempt disabled Christoph Lameter
2008-05-07 7:30 ` Ingo Molnar
2008-05-07 17:04 ` Christoph Lameter
2008-05-07 17:24 ` Christoph Lameter
2008-05-07 18:49 ` Spinlocks: Factor our GENERIC_LOCKBREAK in order to avoid spin with irqs disable Christoph Lameter
2008-05-09 10:26 ` Ingo Molnar
2008-05-09 16:28 ` Christoph Lameter
2008-06-23 17:19 ` Petr Tesarik
2008-06-23 17:54 ` Peter Zijlstra
2008-06-23 18:20 ` Christoph Lameter
2008-06-23 20:39 ` Peter Zijlstra
2008-06-23 20:45 ` Christoph Lameter
2008-06-23 20:58 ` Peter Zijlstra
2008-06-26 2:51 ` Jeremy Fitzhardinge
2008-06-26 6:51 ` Peter Zijlstra
2008-06-26 15:49 ` Jeremy Fitzhardinge
2008-06-26 9:17 ` Petr Tesarik
2008-06-26 17:02 ` Christoph Lameter
2008-06-26 17:48 ` Peter Zijlstra
2008-07-07 11:50 ` Nick Piggin
2008-07-07 11:52 ` Nick Piggin
2008-07-07 15:56 ` Jeremy Fitzhardinge
2008-07-08 2:08 ` Nick Piggin
2008-07-07 15:53 ` Jeremy Fitzhardinge
2008-07-07 19:46 ` Rik van Riel
2008-07-07 20:14 ` Jeremy Fitzhardinge
2008-07-08 2:07 ` Nick Piggin
2008-07-08 5:57 ` Jeremy Fitzhardinge
2008-07-08 8:41 ` Nick Piggin
2008-07-08 15:58 ` Jeremy Fitzhardinge [this message]
2008-05-09 16:35 ` Spinlocks waiting with interrupts disabled / preempt disabled Olaf Weber
2008-05-09 17:56 ` Peter Zijlstra
2008-05-09 18:00 ` Christoph Lameter
2008-05-09 18:06 ` Peter Zijlstra
2008-05-09 20:01 ` Olaf Weber
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