From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id E408DC433E0 for ; Mon, 18 May 2020 18:45:50 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C57352070A for ; Mon, 18 May 2020 18:45:50 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728960AbgERSpu (ORCPT ); Mon, 18 May 2020 14:45:50 -0400 Received: from verein.lst.de ([213.95.11.211]:40098 "EHLO verein.lst.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728794AbgERSpu (ORCPT ); Mon, 18 May 2020 14:45:50 -0400 Received: by verein.lst.de (Postfix, from userid 2407) id 1F0F168B05; Mon, 18 May 2020 20:45:44 +0200 (CEST) Date: Mon, 18 May 2020 20:45:43 +0200 From: Christoph Hellwig To: Thomas Gleixner Cc: Christoph Hellwig , Ming Lei , linux-block@vger.kernel.org, John Garry , Bart Van Assche , Hannes Reinecke Subject: Re: [PATCH 5/9] blk-mq: don't set data->ctx and data->hctx in blk_mq_alloc_request_hctx Message-ID: <20200518184543.GA26157@lst.de> References: <20200518093155.GB35380@T590> <87imgty15d.fsf@nanos.tec.linutronix.de> <20200518115454.GA46364@T590> <20200518131634.GA645@lst.de> <20200518141107.GA50374@T590> <20200518165619.GA17465@lst.de> <87o8qlw0kz.fsf@nanos.tec.linutronix.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <87o8qlw0kz.fsf@nanos.tec.linutronix.de> User-Agent: Mutt/1.5.17 (2007-11-01) Sender: linux-block-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org On Mon, May 18, 2020 at 08:38:04PM +0200, Thomas Gleixner wrote: > > Shouldn't all the per-cpu kthreads also stop as part of the offlining? > > If they don't quiesce before the new blk-mq stop state I think we need > > to make sure they do. It is rather pointless to quiesce the requests > > if a thread that can submit I/O is still live. > > Which kthreads are you talking about? I think PF_KTHREAD threads bound to single cpu will usually be workqueues, yes. > Workqueues? CPU bound workqueues are shut down in > CPUHP_AP_WORKQUEUE_ONLINE state. That's what I mean. If we shut down I/O before that happend we'd have a problem, but as I expected your state machine is smarter than that :)