Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752831Ab3DLAXD (ORCPT ); Thu, 11 Apr 2013 20:23:03 -0400 Received: from mail-qe0-f42.google.com ([209.85.128.42]:60807 "EHLO mail-qe0-f42.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752703Ab3DLAW6 (ORCPT ); Thu, 11 Apr 2013 20:22:58 -0400 Date: Thu, 11 Apr 2013 17:22:52 -0700 From: Tejun Heo To: Mikulas Patocka Cc: Vivek Goyal , Jens Axboe , Mike Snitzer , Milan Broz , dm-devel@redhat.com, Andi Kleen , dm-crypt@saout.de, linux-kernel@vger.kernel.org, Christoph Hellwig , Christian Schmidt , "Alasdair G. Kergon" Subject: Re: [PATCH v2] make dm and dm-crypt forward cgroup context (was: dm-crypt parallelization patches) Message-ID: <20130412002252.GD11956@mtj.dyndns.org> References: <20130409210735.GR6320@redhat.com> <20130410192427.GA14911@redhat.com> <20130410235009.GI17641@mtj.dyndns.org> <20130411195203.GA11956@mtj.dyndns.org> <20130411200005.GB11956@mtj.dyndns.org> 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) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1138 Lines: 24 On Thu, Apr 11, 2013 at 08:06:10PM -0400, Mikulas Patocka wrote: > All that I can tell you is that adding an empty atomic operation > "cmpxchg(&bio->bi_css->refcnt, bio->bi_css->refcnt, bio->bi_css->refcnt);" > to bio_clone_context and bio_disassociate_task increases the time to run a > benchmark from 23 to 40 seconds. Right, linear target on ramdisk, very realistic, and you know what, hell with dm, let's just hand code everything into submit_bio(). I'm sure it will speed up your test case significantly. If this actually matters, improve it in *sane* way. Make the refcnts per-cpu and not use atomic ops. In fact, we already have proposed implementation of percpu refcnt which is being used by aio restructure patches and likely to be included in some form. It's not quite ready yet, so please work on something useful like that instead of continuing this non-sense. -- 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/