Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755532Ab3CZVAd (ORCPT ); Tue, 26 Mar 2013 17:00:33 -0400 Received: from mail-wi0-f174.google.com ([209.85.212.174]:65459 "EHLO mail-wi0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754690Ab3CZU75 (ORCPT ); Tue, 26 Mar 2013 16:59:57 -0400 Message-ID: <51520C09.9050808@gmail.com> Date: Tue, 26 Mar 2013 21:58:49 +0100 From: Milan Broz User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:17.0) Gecko/20130307 Thunderbird/17.0.4 MIME-Version: 1.0 To: Mike Snitzer CC: Milan Broz , Mikulas Patocka , dm-devel@redhat.com, Andi Kleen , dm-crypt@saout.de, linux-kernel@vger.kernel.org, Christoph Hellwig , Christian Schmidt , tj@kernel.org Subject: Re: dm-crypt performance References: <20130326122713.GC27610@agk-dp.fab.redhat.com> <5151FF82.6090405@gmail.com> <20130326202837.GA5599@redhat.com> In-Reply-To: <20130326202837.GA5599@redhat.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1795 Lines: 41 On 26.3.2013 21:28, Mike Snitzer wrote: > On Tue, Mar 26 2013 at 4:05pm -0400, > Milan Broz wrote: > >>> On Mon, Mar 25, 2013 at 11:47:22PM -0400, Mikulas Patocka wrote: >>> >>>> For best performance we could use the unbound workqueue implementation >>>> with request sorting, if people don't object to the request sorting being >>>> done in dm-crypt. >> >> So again: >> >> - why IO scheduler is not working properly here? Do it need some extensions? >> If fixed, it can help even is some other non-dmcrypt IO patterns. >> (I mean dmcrypt can set some special parameter for underlying device queue >> automagically to fine-tune sorting parameters.) > > Not sure, but IO scheduler changes are fairly slow to materialize given > the potential for adverse side-effects. Are you so surprised that a > shotgun blast of IOs might make the IO schduler less optimal than if > some basic sorting were done at the layer above? All I said is that I think the problems should be solved on proper layer where are already all mechanisms to properly control it. And only if it is not possible then use such workarounds. CPU bounded io in dmcrypt is in kernel for >2 years and I know about just few cases where it caused real problems. Maybe I am mistaken - then now is ideal time for people to complain :) Anyway, are we talking about the same Mikulas' patch I tested months ago or you have something new? I mean this part from series of dmcrypt patches: http://mbroz.fedorapeople.org/dm-crypt/3.6-rc/dm-crypt-25-sort-writes.patch Milan -- 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/