Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1761894AbYFWRyq (ORCPT ); Mon, 23 Jun 2008 13:54:46 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1757035AbYFWRyg (ORCPT ); Mon, 23 Jun 2008 13:54:36 -0400 Received: from bombadil.infradead.org ([18.85.46.34]:39815 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1762006AbYFWRyf (ORCPT ); Mon, 23 Jun 2008 13:54:35 -0400 Subject: Re: Spinlocks: Factor our GENERIC_LOCKBREAK in order to avoid spin with irqs disable From: Peter Zijlstra To: Petr Tesarik Cc: Christoph Lameter , Ingo Molnar , linux-kernel@vger.kernel.org In-Reply-To: <1214241561.19392.21.camel@elijah.suse.cz> References: <20080507073017.GJ32195@elte.hu> <1214241561.19392.21.camel@elijah.suse.cz> Content-Type: text/plain Date: Mon, 23 Jun 2008 19:54:13 +0200 Message-Id: <1214243653.3223.363.camel@lappy.programming.kicks-ass.net> Mime-Version: 1.0 X-Mailer: Evolution 2.22.2 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2392 Lines: 57 On Mon, 2008-06-23 at 19:19 +0200, Petr Tesarik wrote: > On Wed, 2008-05-07 at 11:49 -0700, Christoph Lameter wrote: > > Subject: Spinlocks: Factor our GENERIC_LOCKBREAK in order to avoid spin with irqs disabled > > > > The nice spinlock functions that enable interrupts while spinning are only > > usable if GENERIC_LOCKBREAK is set (and we do not debug locks but lock > > debugging would not be used for a production configuration). > > > > Factor out the dependencies on the ->lock_break field from the nice functions > > into a set of BREAKLOCK macros (cannot be functions since the type of the lock > > variable varies). > > > > The nice spinlock function can then also be used if !GENERIC_LOCKBREAK > > > > Signed-off-by: Christoph Lameter > > > > --- > > kernel/spinlock.c | 40 ++++++++++++++++++++++++++++++---------- > > 1 file changed, 30 insertions(+), 10 deletions(-) > > > > Index: linux-2.6/kernel/spinlock.c > > =================================================================== > > --- linux-2.6.orig/kernel/spinlock.c 2008-05-07 11:19:31.000000000 -0700 > > +++ linux-2.6/kernel/spinlock.c 2008-05-07 11:40:56.000000000 -0700 > > @@ -65,7 +65,7 @@ EXPORT_SYMBOL(_write_trylock); > > * even on CONFIG_PREEMPT, because lockdep assumes that interrupts are > > * not re-enabled during lock-acquire (which the preempt-spin-ops do): > > */ > > -#if !defined(CONFIG_GENERIC_LOCKBREAK) || defined(CONFIG_DEBUG_LOCK_ALLOC) > > +#ifdef CONFIG_DEBUG_LOCK_ALLOC > > Maybe I'm just blind, but doesn't this change effectively disable any > arch-specific optimized code for _raw_*_lock? > > 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? No, I think you're right. I've been playing with these patches: http://programming.kicks-ass.net/kernel-patches/spinlocks/ But as it stands it breaks !CONFIG_PREEMPT... ought to find some other cycles to spend on it.. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/