From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx0b-00082601.pphosted.com ([67.231.153.30]:52875 "EHLO mx0b-00082601.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750714AbdAXQEY (ORCPT ); Tue, 24 Jan 2017 11:04:24 -0500 Subject: Re: [PATCH] queue stall with blk-mq-sched To: Hannes Reinecke References: CC: "linux-block@vger.kernel.org" , Omar Sandoval From: Jens Axboe Message-ID: <1c9beccc-c7cc-dd3e-703d-e91d8110ec86@fb.com> Date: Tue, 24 Jan 2017 09:03:26 -0700 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset="utf-8" Sender: linux-block-owner@vger.kernel.org List-Id: linux-block@vger.kernel.org On 01/24/2017 08:54 AM, Hannes Reinecke wrote: > Hi Jens, > > I'm trying to debug a queue stall with your blk-mq-sched branch; with my > latest mpt3sas patches fio stops basically directly after starting a > sequential read :-( > > I've debugged things and came up with the attached patch; we need to > restart waiters with blk_mq_tag_idle() after completing a tag. > We're already calling blk_mq_tag_busy() when fetching a tag, so I think > calling blk_mq_tag_idle() is required when retiring a tag. I'll take a look at this. It sounds like all your grief is related to shared tag maps, which I don't have anything that uses here. I'll see if we are leaking it, you should be able to check that by reading the 'active' file in the sysfs directory. -- Jens Axboe