Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756431Ab2BGAbY (ORCPT ); Mon, 6 Feb 2012 19:31:24 -0500 Received: from mail-qy0-f174.google.com ([209.85.216.174]:47712 "EHLO mail-qy0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755895Ab2BGAbX convert rfc822-to-8bit (ORCPT ); Mon, 6 Feb 2012 19:31:23 -0500 MIME-Version: 1.0 In-Reply-To: <20120206203604.GC21292@google.com> References: <1328514611.21268.66.camel@sli10-conroe> <20120206151219.GC30752@redhat.com> <4F2FFB21.9000202@kernel.dk> <20120206163721.GF30752@redhat.com> <20120206164428.GA21292@google.com> <20120206172706.GB21292@google.com> <20120206203604.GC21292@google.com> Date: Tue, 7 Feb 2012 08:31:22 +0800 X-Google-Sender-Auth: HzjV51BtT1IdXoD42PXJlk5QTws Message-ID: Subject: Re: [patch]block: fix ioc locking warning From: Shaohua Li To: Tejun Heo Cc: Linus Torvalds , Vivek Goyal , Jens Axboe , lkml , Knut Petersen , mroos@linux.ee Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1317 Lines: 27 2012/2/7 Tejun Heo : > On Mon, Feb 06, 2012 at 09:27:06AM -0800, Tejun Heo wrote: >> It's one wq scheduling on exit for any task which has issued an IO. ?I >> don't think it would matter except for task fork/exit microbenchs (or >> workloads which approximate to that). ?I'll get some measurements and >> strip the optimization if it doesn't really show up. > > I'm still playing with test methods and getting numbers but the > following is the simplified one of the three setups I'm playing with - > the current one, simplified and no optimization. ?There *seems* to be > appreciable performance degradation on fork/exit w/ ioc microbenchs so > I'm likely to go with the following. ?I'll post when I know more. Hi, Since you are talking about performance, one of our microbenchmark (swap) shows a regression. Alex bisect it to be b2efa05265d62bc2, which is related to the ioc change. A little strange to me, don't expect such change can cause performance issue. I haven't double check the issue, but if you have ideas, please let me know. Thanks, Shaohua -- 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/