From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-it0-f41.google.com ([209.85.214.41]:51662 "EHLO mail-it0-f41.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751691AbeEVUUk (ORCPT ); Tue, 22 May 2018 16:20:40 -0400 Received: by mail-it0-f41.google.com with SMTP id d10-v6so1005681itj.1 for ; Tue, 22 May 2018 13:20:39 -0700 (PDT) Subject: Re: [PATCH V2] blk-mq: avoid to starve tag allocation after allocation process migrates To: Ming Lei Cc: linux-block@vger.kernel.org, stable@vger.kernel.org, Omar Sandoval References: <20180519074406.6045-1-ming.lei@redhat.com> From: Jens Axboe Message-ID: <9ea0bf13-8891-0214-d735-2088827b2937@kernel.dk> Date: Tue, 22 May 2018 14:20:37 -0600 MIME-Version: 1.0 In-Reply-To: <20180519074406.6045-1-ming.lei@redhat.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: stable-owner@vger.kernel.org List-ID: On 5/19/18 1:44 AM, Ming Lei wrote: > When the allocation process is scheduled back and the mapped hw queue is > changed, do one extra wake up on orignal queue for compensating wake up > miss, so other allocations on the orignal queue won't be starved. > > This patch fixes one request allocation hang issue, which can be > triggered easily in case of very low nr_request. Can you explain what the actual bug is? The commit message doesn't really say, it just explains what the code change does. What wake up miss? -- Jens Axboe