Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932517Ab1C3NrM (ORCPT ); Wed, 30 Mar 2011 09:47:12 -0400 Received: from mx1.redhat.com ([209.132.183.28]:49517 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755941Ab1C3NrL (ORCPT ); Wed, 30 Mar 2011 09:47:11 -0400 Date: Wed, 30 Mar 2011 09:46:58 -0400 From: Vivek Goyal To: Tejun Heo Cc: Jens Axboe , Jeff Moyer , Mike Snitzer , Markus Trippelsdorf , Sergey Senozhatsky , linux-kernel@vger.kernel.org, Chris Mason Subject: Re: [PATCH] block: eliminate ELEVATOR_INSERT_REQUEUE Message-ID: <20110330134658.GB1291@redhat.com> References: <4D8CF202.9010809@kernel.dk> <20110326042156.GB28458@redhat.com> <20110328082321.GC16530@htj.dyndns.org> <20110328221547.GA1118@redhat.com> <20110329175458.GE24485@redhat.com> <20110330074123.GA17523@htj.dyndns.org> <20110330075752.GC17523@htj.dyndns.org> <4D92E2CD.6000909@kernel.dk> <20110330080203.GD17523@htj.dyndns.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20110330080203.GD17523@htj.dyndns.org> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1076 Lines: 27 On Wed, Mar 30, 2011 at 10:02:03AM +0200, Tejun Heo wrote: > Hello, Jens. > > On Wed, Mar 30, 2011 at 09:59:09AM +0200, Jens Axboe wrote: > > Pure front insert should be used for requeue and internal commands (like > > spin up this drive, or get error information). Flush should append to > > the dispatch list. > > Yeah, right. The reason I used REQUEUE/FRONT was because BACK > insertion involves draining the elevator and then appending the > request at the end of the dispatch queue, which is unnecessary and > inefficient. So, front insertion was a quick work around that. If > we're removing elv_insert(), we can just append directly to the > dispatch queue from flush code. Hi Tejun, With ordering semantics gone, do we still need to drain the elevator before queuing flush at the end of request queue. Thanks Vivek -- 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/