Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754324AbZKLUop (ORCPT ); Thu, 12 Nov 2009 15:44:45 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754291AbZKLUol (ORCPT ); Thu, 12 Nov 2009 15:44:41 -0500 Received: from mx1.redhat.com ([209.132.183.28]:56657 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754281AbZKLUoj (ORCPT ); Thu, 12 Nov 2009 15:44:39 -0500 From: Jeff Moyer To: Jan Kara Cc: jens.axboe@oracle.com, LKML , Chris Mason , Andrew Morton , Mike Galbraith , mszeredi@suse.de Subject: Re: Performance regression in IO scheduler still there References: <20091026172012.GC7233@duck.suse.cz> <20091111141031.GA21511@duck.suse.cz> <20091112172941.GK14528@duck.suse.cz> X-PGP-KeyID: 1F78E1B4 X-PGP-CertKey: F6FE 280D 8293 F72C 65FD 5A58 1FF8 A7CA 1F78 E1B4 X-PCLoadLetter: What the f**k does that mean? Date: Thu, 12 Nov 2009 15:44:02 -0500 In-Reply-To: <20091112172941.GK14528@duck.suse.cz> (Jan Kara's message of "Thu, 12 Nov 2009 18:29:41 +0100") Message-ID: User-Agent: Gnus/5.110011 (No Gnus v0.11) Emacs/23.1 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1389 Lines: 36 Jan Kara writes: > On Wed 11-11-09 12:43:30, Jeff Moyer wrote: >> Jan Kara writes: >> >> > Sadly, I don't see the improvement you can see :(. The numbers are the >> > same regardless low_latency set to 0: >> > 2.6.32-rc5 low_latency = 0: >> > 37.39 36.43 36.51 -> 36.776667 0.434920 >> > But my testing environment is a plain SATA drive so that probably >> > explains the difference... >> >> I just retested (10 runs for each kernel) on a SATA disk with no NCQ >> support and I could not see a difference. I'll try to dig up a disk >> that support NCQ. Is that what you're using for testing? > I don't think I am. How do I find out? Good question. ;-) I grep for NCQ in dmesg output and make sure it's greater than 0/32. There may be a better way, though. >> 2.6.29 2.6.32-rc6,low_latency=0 >> ---------------------------------- >> Average: 34.6648 34.4475 >> Pop.Std.Dev.: 0.55523 0.21981 > Hmm, strange. Miklos Szeredi tried tiobench on his machine and he also > saw the regression. I'll try to think what could make the difference. OK, I'll try again. Cheers, Jeff -- 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/