Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753428Ab3C1Up2 (ORCPT ); Thu, 28 Mar 2013 16:45:28 -0400 Received: from mail-da0-f44.google.com ([209.85.210.44]:57662 "EHLO mail-da0-f44.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751160Ab3C1Up1 (ORCPT ); Thu, 28 Mar 2013 16:45:27 -0400 Date: Thu, 28 Mar 2013 13:45:22 -0700 From: Tejun Heo To: Vivek Goyal Cc: Mike Snitzer , Milan Broz , Mikulas Patocka , dm-devel@redhat.com, Andi Kleen , dm-crypt@saout.de, linux-kernel@vger.kernel.org, Christoph Hellwig , Christian Schmidt , Jens Axboe Subject: Re: dm-crypt performance Message-ID: <20130328204522.GA25501@mtj.dyndns.org> References: <20130326122713.GC27610@agk-dp.fab.redhat.com> <5151FF82.6090405@gmail.com> <20130326202837.GA5599@redhat.com> <20130328185327.GF14088@htj.dyndns.org> <20130328193343.GA15969@redhat.com> <20130328194443.GG14088@htj.dyndns.org> <20130328203808.GC15969@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20130328203808.GC15969@redhat.com> 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: 1292 Lines: 29 Hello, On Thu, Mar 28, 2013 at 04:38:08PM -0400, Vivek Goyal wrote: > If timing of unordered IO is an issue, then dm-crypt can try > to batch IO submission using blk_start_plug()/blk_finish_plug(). That way > dm-crypt can batch bio and control submission and there should not > be a need to put specific ordering logic in dm-crypt. Yes, it has to preserve and propagate the plugging boundaries and if you think about the implementation, maintaining issue order don't really need to be "sorted" per-se. Just keep the list of bios received but still going through encryption in the received order with a counter of in-progress bios in the plugging boundary. Link the outputs to the source bios somehow and when the counter hits zero, issue them in the same order. While keeping the specific order itself might not be essential, it's not gonna add any significant complexity or runtime overhead and I think it generally is a good idea for stacking drivers to preserve as much information and context as possible in general. Thanks. -- tejun -- 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/