Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S262245AbVCJE3x (ORCPT ); Wed, 9 Mar 2005 23:29:53 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S262293AbVCIXMx (ORCPT ); Wed, 9 Mar 2005 18:12:53 -0500 Received: from fire.osdl.org ([65.172.181.4]:38887 "EHLO smtp.osdl.org") by vger.kernel.org with ESMTP id S261652AbVCIWpd (ORCPT ); Wed, 9 Mar 2005 17:45:33 -0500 Date: Wed, 9 Mar 2005 14:44:58 -0800 From: Andrew Morton To: "Chen, Kenneth W" Cc: linux-kernel@vger.kernel.org, axboe@suse.de Subject: Re: Direct io on block device has performance regression on 2.6.x kernel Message-Id: <20050309144458.2cbc554e.akpm@osdl.org> In-Reply-To: <200503092159.j29LxIg26267@unix-os.sc.intel.com> References: <20050309120458.7c25f5e3.akpm@osdl.org> <200503092159.j29LxIg26267@unix-os.sc.intel.com> X-Mailer: Sylpheed version 0.9.7 (GTK+ 1.2.10; i386-redhat-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 690 Lines: 20 "Chen, Kenneth W" wrote: > > > Did you generate a kernel profile? > > Top 40 kernel hot functions, percentage is normalized to kernel utilization. > > _spin_unlock_irqrestore 23.54% > _spin_unlock_irq 19.27% Cripes. Is that with CONFIG_PREEMPT? If so, and if you disable CONFIG_PREEMPT, this cost should be accounting the the spin_unlock() caller and we can see who the culprit is. Perhaps dio->bio_lock. - 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/