From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S262342AbVCILXM (ORCPT ); Wed, 9 Mar 2005 06:23:12 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S262292AbVCILWh (ORCPT ); Wed, 9 Mar 2005 06:22:37 -0500 Received: from one.firstfloor.org ([213.235.205.2]:3751 "EHLO one.firstfloor.org") by vger.kernel.org with ESMTP id S261570AbVCILVC (ORCPT ); Wed, 9 Mar 2005 06:21:02 -0500 To: Arjan van de Ven Cc: David Howells , Andrew Morton , Badari Pulavarty , linux-aio@kvack.org, linux-kernel@vger.kernel.org, christoph@graphe.net Subject: Re: aio stress panic on 2.6.11-mm1 References: <20050308170107.231a145c.akpm@osdl.org> <1110327267.24286.139.camel@dyn318077bld.beaverton.ibm.com> <18744.1110364438@redhat.com> <20050309110404.GA4088@in.ibm.com> <1110366614.6280.86.camel@laptopd505.fenrus.org> From: Andi Kleen Date: Wed, 09 Mar 2005 12:21:01 +0100 In-Reply-To: <1110366614.6280.86.camel@laptopd505.fenrus.org> (Arjan van de Ven's message of "Wed, 09 Mar 2005 12:10:13 +0100") Message-ID: User-Agent: Gnus/5.110002 (No Gnus v0.2) Emacs/21.3 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Arjan van de Ven writes: > On Wed, 2005-03-09 at 16:34 +0530, Suparna Bhattacharya wrote: >> Any sense of how costly it is to use spin_lock_irq's vs spin_lock >> (across different architectures) ? Isn't rwsem used very widely ? > > oh also rwsems aren't used all that much simply because they are quite > more expensive than regular semaphores, so that you need a HUGE bias in > reader/writer ratio to make it even worth it... I agree. I think in fact once Christopher L's lockless page fault fast path goes in it would be a good idea to reevaluate if mmap_sem should be really a rwsem and possibly change it back to a normal semaphore that perhaps gets dropped only on a page cache miss. -Andi