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 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 2AFCFC0015E for ; Fri, 11 Aug 2023 13:11:03 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:In-Reply-To:Content-Type: MIME-Version:References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=wqPO3fjYCFSZoxri1VRwX01Ep7+zcmQMJe0Oi2gC3UY=; b=sy05y1NEWEy/P5/Zk0zskflrnt zi9+y2xS4NNcJfa62k8xtlMUhrdg8oRmhKgHO19CFdB6pgw3JZvS5vphxK+K6Kxer3TstumlFPV/c etwpx0i3F0K4/F5o8bo2HtwCyX6ySdcp6j74nQOTrLKf3t31HEYLkxyFyyAx6VDn8VYFiLEqxPymA C94dpD41mGsFpKputzuGPwMlgfiBqgemXMNl+cR1nbmLK5E3V99h7S72pu9+SWg6VO0qyFT71H5Dv XHLWMCRO68PFB2FQltVtGxjjNfZPLwd27VdRQaEjgfFpg5dQLb2tZOgowcVoKjRfNxmutGEEnhFnk +BYgw8IA==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.96 #2 (Red Hat Linux)) id 1qURut-00Ah17-1f; Fri, 11 Aug 2023 13:10:59 +0000 Received: from verein.lst.de ([213.95.11.211]) by bombadil.infradead.org with esmtps (Exim 4.96 #2 (Red Hat Linux)) id 1qURuq-00AgyY-2N; Fri, 11 Aug 2023 13:10:58 +0000 Received: by verein.lst.de (Postfix, from userid 2407) id 4DD1867373; Fri, 11 Aug 2023 15:10:49 +0200 (CEST) Date: Fri, 11 Aug 2023 15:10:49 +0200 From: Christoph Hellwig To: Ming Lei Cc: Christoph Hellwig , Jens Axboe , linux-nvme@lists.infradead.org, "Martin K . Petersen" , linux-scsi@vger.kernel.org, linux-block@vger.kernel.org, Wen Xiong , Keith Busch , linuxppc-dev@lists.ozlabs.org, Dave Young , kexec@lists.infradead.org, linux-kernel@vger.kernel.org, Baoquan He , Pingfan Liu Subject: Re: [PATCH V3 01/14] blk-mq: add blk_mq_max_nr_hw_queues() Message-ID: <20230811131049.GA20991@lst.de> References: <20230808104239.146085-1-ming.lei@redhat.com> <20230808104239.146085-2-ming.lei@redhat.com> <20230809134401.GA31852@lst.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.17 (2007-11-01) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20230811_061056_924727_880FA0D7 X-CRM114-Status: GOOD ( 12.86 ) X-BeenThere: linux-nvme@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "Linux-nvme" Errors-To: linux-nvme-bounces+linux-nvme=archiver.kernel.org@lists.infradead.org On Thu, Aug 10, 2023 at 08:09:27AM +0800, Ming Lei wrote: > 1) some archs support 'nr_cpus=1' for kdump kernel, which is fine, since > num_possible_cpus becomes 1. > > 2) some archs do not support 'nr_cpus=1', and have to rely on > 'max_cpus=1', so num_possible_cpus isn't changed, and kernel just boots > with single online cpu. That causes trouble because blk-mq limits single > queue. And we need to fix case 2. We need to drop the is_kdump support, and if they want to force less cpus they need to make nr_cpus=1 work.