Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751941AbdHCJcv (ORCPT ); Thu, 3 Aug 2017 05:32:51 -0400 Received: from mail-vk0-f44.google.com ([209.85.213.44]:33160 "EHLO mail-vk0-f44.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751258AbdHCJct (ORCPT ); Thu, 3 Aug 2017 05:32:49 -0400 MIME-Version: 1.0 In-Reply-To: References: <20170803085115.r2jfz2lofy5spfdb@techsingularity.net> From: Ming Lei Date: Thu, 3 Aug 2017 17:32:48 +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 , Ming Lei 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: 1273 Lines: 32 On Thu, Aug 3, 2017 at 5:17 PM, 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 BTW, the above patches(V1) can be found in the following tree: https://github.com/ming1/linux/commits/blk-mq-dispatch_for_scsi.V1 V2 has already been done but not posted out yet, because the performance test on SRP isn't completed: https://github.com/ming1/linux/commits/blk-mq-dispatch_for_scsi.V2 Thanks, Ming Lei