From: Peter Zijlstra <a.p.zijlstra@chello.nl>
To: Christoph Lameter <clameter@sgi.com>
Cc: 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: Mon, 23 Jun 2008 22:39:53 +0200 [thread overview]
Message-ID: <1214253593.11254.30.camel@twins> (raw)
In-Reply-To: <Pine.LNX.4.64.0806231115420.22557@schroedinger.engr.sgi.com>
On Mon, 2008-06-23 at 11:20 -0700, Christoph Lameter wrote:
> On Mon, 23 Jun 2008, Petr Tesarik wrote:
>
> > Maybe I'm just blind, but doesn't this change effectively disable any
> > arch-specific optimized code for _raw_*_lock?
>
> True. Only the __raw_xxx_trylock is still used.
>
> > If CONFIG_DEBUG_LOCK_ALLOC is set, then CONFIG_DEBUG_SPINLOCK must also
> > be set, so in that case the debugging versions of _raw_*_lock are used.
> > But if CONFIG_DEBUG_LOCK_ALLOC is _not_ set, then the locks are built
> > with _trylock and _can_lock primitives.
> >
> > What am I missing here?
>
> It is good that the locks are build with _trylock and _can_lock because
> then we can reenable interrupts while spinning.
Well, good and bad, the turn side is that fairness schemes like ticket
locks are utterly defeated.
next prev parent reply other threads:[~2008-06-23 20:39 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 [this message]
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
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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