Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756152AbXKFT0Y (ORCPT ); Tue, 6 Nov 2007 14:26:24 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754213AbXKFT0Q (ORCPT ); Tue, 6 Nov 2007 14:26:16 -0500 Received: from brick.kernel.dk ([87.55.233.238]:1424 "EHLO kernel.dk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754031AbXKFT0Q (ORCPT ); Tue, 6 Nov 2007 14:26:16 -0500 Date: Tue, 6 Nov 2007 20:26:11 +0100 From: Jens Axboe To: Oleg Nesterov Cc: Andrew Morton , Nick , linux-kernel@vger.kernel.org Subject: Re: [PATCH] cfq: fix IOPRIO_CLASS_IDLE delays Message-ID: <20071106192611.GS1767@kernel.dk> References: <20071106200510.GA11435@tv-sign.ru> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20071106200510.GA11435@tv-sign.ru> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 787 Lines: 25 On Tue, Nov 06 2007, Oleg Nesterov wrote: > After the fresh boot: > > ionice -c3 -p $$ > echo cfq >> /sys/block/XXX/queue/scheduler > dd if=/dev/XXX of=/dev/null bs=512 count=1 > > Now dd hangs in D state and the queue is completely stalled for approximately > INITIAL_JIFFIES + CFQ_IDLE_GRACE jiffies. This is because cfq_init_queue() > forgets to initialize cfq_data->last_end_request. Another good catch, thanks Oleg! > (I guess this patch is not complete, overflow is still possible) Hmm, where would it overflow? -- Jens Axboe - 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/