From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753350AbYGFEQV (ORCPT ); Sun, 6 Jul 2008 00:16:21 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1750838AbYGFEQO (ORCPT ); Sun, 6 Jul 2008 00:16:14 -0400 Received: from BISCAYNE-ONE-STATION.MIT.EDU ([18.7.7.80]:38018 "EHLO biscayne-one-station.mit.edu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750710AbYGFEQN (ORCPT ); Sun, 6 Jul 2008 00:16:13 -0400 Date: Sun, 6 Jul 2008 00:15:02 -0400 From: Theodore Tso To: Arjan van de Ven Cc: akpm@linux-foundation.org, jens.axboe@oracle.com, linux-kernel@vger.kernel.org Subject: Re: PATCH] fix potential latency issues in JBD's journal code Message-ID: <20080706041502.GB21990@mit.edu> Mail-Followup-To: Theodore Tso , Arjan van de Ven , akpm@linux-foundation.org, jens.axboe@oracle.com, linux-kernel@vger.kernel.org References: <20080704192929.2c4dd4ca@infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20080704192929.2c4dd4ca@infradead.org> User-Agent: Mutt/1.5.17+20080114 (2008-01-14) X-Spam-Flag: NO X-Spam-Score: 0.00 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Jul 04, 2008 at 07:29:29PM -0700, Arjan van de Ven wrote: > @@ -165,7 +165,7 @@ static void journal_do_submit_data(struct buffer_head **wbuf, int bufs) > for (i = 0; i < bufs; i++) { > wbuf[i]->b_end_io = end_buffer_write_sync; > /* We use-up our safety reference in submit_bh() */ > - submit_bh(WRITE, wbuf[i]); > + submit_bh(WRITE_SYNC, wbuf[i]); > } > } So I started looking at this patch more closely when trying to replicate it for ext4. Don't you want to only use WRITE_SYNC() only for the very last time in the loop? Otherwise you end up unplugging the queue after each bufferhead, which wouldn't be a good thing, right? - Ted