From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754499Ab2CVG26 (ORCPT ); Thu, 22 Mar 2012 02:28:58 -0400 Received: from 173-166-109-252-newengland.hfc.comcastbusiness.net ([173.166.109.252]:41882 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750913Ab2CVG25 (ORCPT ); Thu, 22 Mar 2012 02:28:57 -0400 Date: Thu, 22 Mar 2012 02:28:51 -0400 From: Christoph Hellwig To: "Martin K. Petersen" Cc: Shaohua Li , Vivek Goyal , linux-kernel@vger.kernel.org, linux-raid@vger.kernel.org, neilb@suse.de, axboe@kernel.dk Subject: Re: [patch v2 2/6] blk: dont allow discard request merge temporarily Message-ID: <20120322062850.GA25288@infradead.org> References: <20120316073213.656519005@fusionio.com> <20120316073512.485027511@fusionio.com> <20120320162157.GE17071@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.21 (2010-09-15) X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org See http://www.infradead.org/rpr.html Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Mar 21, 2012 at 10:18:54PM -0400, Martin K. Petersen wrote: > >>>>> "Shaohua" == Shaohua Li writes: > > Shaohua> Enabling discard merge is required for device with slow discard > Shaohua> (and very helpful for raid), > > Before RAID support there really wasn't much point. That's one of the > reasons the current discard merge code has survived despite being > completely broken. I've actually send repeated bug reports about it beeing broken when I enabled async discard in XFS which led to merges, and debugged it down to beeing a problem with merges. But Jens didn't like my patch to mark them nomerged, so we still couldn't commit the async discard support for XFS which would have helped quite a bit with discard performance.