Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751988AbdHCJoM (ORCPT ); Thu, 3 Aug 2017 05:44:12 -0400 Received: from mail-wm0-f53.google.com ([74.125.82.53]:35416 "EHLO mail-wm0-f53.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751811AbdHCJoK (ORCPT ); Thu, 3 Aug 2017 05:44:10 -0400 Content-Type: text/plain; charset=us-ascii Mime-Version: 1.0 (Mac OS X Mail 9.3 \(3124\)) Subject: Re: Switching to MQ by default may generate some bug reports From: Paolo Valente In-Reply-To: <20170803094242.wol67mmga3om4gjp@techsingularity.net> Date: Thu, 3 Aug 2017 11:44:06 +0200 Cc: Ming Lei , Christoph Hellwig , Jens Axboe , Linux Kernel Mailing List , linux-block Message-Id: References: <20170803085115.r2jfz2lofy5spfdb@techsingularity.net> <20170803094242.wol67mmga3om4gjp@techsingularity.net> To: Mel Gorman X-Mailer: Apple Mail (2.3124) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: 8bit X-MIME-Autoconverted: from quoted-printable to 8bit by nfs id v739iGCU031777 Content-Length: 1343 Lines: 38 > Il giorno 03 ago 2017, alle ore 11:42, Mel Gorman ha scritto: > > On Thu, Aug 03, 2017 at 05:17:21PM +0800, Ming Lei wrote: >> Hi Mel Gorman, >> >> On Thu, Aug 3, 2017 at 4:51 PM, Mel Gorman wrote: >>> Hi Christoph, >>> >>> I know the reasons for switching to MQ by default but just be aware that it's >>> not without hazards albeit it the biggest issues I've seen are switching >>> CFQ to BFQ. On my home grid, there is some experimental automatic testing >>> running every few weeks searching for regressions. Yesterday, it noticed >>> that creating some work files for a postgres simulator called pgioperf >>> was 38.33% slower and it auto-bisected to the switch to MQ. This is just >>> linearly writing two files for testing on another benchmark and is not >>> remarkable. The relevant part of the report is >> >> We saw some SCSI-MQ performance issue too, please see if the following >> patchset fixes your issue: >> >> http://marc.info/?l=linux-block&m=150151989915776&w=2 >> > > That series is dealing with problems with legacy-deadline vs mq-none where > as the bulk of the problems reported in this mail are related to > legacy-CFQ vs mq-BFQ. > Out-of-curiosity: you get no regression with mq-none or mq-deadline? Thanks, Paolo > -- > Mel Gorman > SUSE Labs