From: Ric Wheeler Subject: Re: [PATCH 2/2] Add batched discard support for ext4. Date: Wed, 21 Apr 2010 17:03:45 -0400 Message-ID: <4BCF6831.7080506@redhat.com> References: <1271674527-2977-1-git-send-email-lczerner@redhat.com> <1271674527-2977-2-git-send-email-lczerner@redhat.com> <1271674527-2977-3-git-send-email-lczerner@redhat.com> <4BCE6243.5010209@teksavvy.com> <4BCE66C5.3060906@redhat.com> <4BCF4C53.3010608@redhat.com> <4BCF67A9.2040902@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: Eric Sandeen , Greg Freemyer , Jeff Moyer , Mark Lord , Lukas Czerner , linux-ext4@vger.kernel.org, Edward Shishkin , Christoph Hellwig To: sandeen@redhat.com Return-path: Received: from mx1.redhat.com ([209.132.183.28]:41037 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753046Ab0DUVDt (ORCPT ); Wed, 21 Apr 2010 17:03:49 -0400 In-Reply-To: <4BCF67A9.2040902@redhat.com> Sender: linux-ext4-owner@vger.kernel.org List-ID: On 04/21/2010 05:01 PM, Eric Sandeen wrote: > On 04/21/2010 03:44 PM, Greg Freemyer wrote: > > >> Mark's benchmarks showed this as doable in seconds which seems like a >> reasonable amount of time for a mount time operation. >> > All the other things aside, mount-time is interesting, but it's an > infrequent operation, at least in my world. I think we need something > that can be done runtime. > > For anything with uptime, I don't think it's acceptable to wait until > the next mount to trim unused blocks. > > But as long as the mechanism can be called either at mount time and/or > kicked off runtime somehow, I'm happy. > > -Eric > That makes sense to me. Most enterprise servers will go without remounting a file system for (hopefully!) a very long time. It is really important to keep in mind that this is not just a laptop feature for laptop SSD's, this is also used by high end arrays and *could* be useful for virt IO, etc as well :-) ric