Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752037AbdHCJRZ (ORCPT ); Thu, 3 Aug 2017 05:17:25 -0400 Received: from mail-ua0-f170.google.com ([209.85.217.170]:34868 "EHLO mail-ua0-f170.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751295AbdHCJRW (ORCPT ); Thu, 3 Aug 2017 05:17:22 -0400 MIME-Version: 1.0 In-Reply-To: <20170803085115.r2jfz2lofy5spfdb@techsingularity.net> References: <20170803085115.r2jfz2lofy5spfdb@techsingularity.net> From: Ming Lei Date: Thu, 3 Aug 2017 17:17:21 +0800 Message-ID: Subject: Re: Switching to MQ by default may generate some bug reports To: Mel Gorman Cc: Christoph Hellwig , Jens Axboe , Linux Kernel Mailing List , linux-block , Paolo Valente Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 858 Lines: 21 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 Thanks, Ming