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 93D21EB64DC for ; Tue, 11 Jul 2023 07:01:29 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: Message-ID:Subject:Cc:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=RWlMtWC0dxX3/jRt2OQgoURH5ZuxDRFPxiCzAov7sw8=; b=RUtxYvdDumC5kr np+fgoLbwhjuxcWyCVV7rUSXVJxEatgBcFWZ71P5m1NOfuKSEz6VXEkMuJxtuX/5VmLCJYw4lV4Tf 6E2JavLQ2n7a3o4ghVwBckV9quNPODArK5ix/wowwg5nKWQelpDS85vUPnRZNGO8L0BcAoWruXZIh KN/AVJckcp1P+g3wNs66oDsbdL2aT0A24G5iYS0uwhDxA+n6q9GvO7abLy2y3eOvWHU2qcfu7uE/9 iRSk7mctfRGqd6sw7RqaCXS5K07TbXJwuHO4YU0R+EYpH0axoG0t5EowzAsTVMckdILlg/deMIH0j 5roxkM1asQrUojm+8Vog==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.96 #2 (Red Hat Linux)) id 1qJ7Mm-00DwHr-0j; Tue, 11 Jul 2023 07:00:56 +0000 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]) by bombadil.infradead.org with esmtps (Exim 4.96 #2 (Red Hat Linux)) id 1qJ7Mj-00DwGA-07 for linux-arm-kernel@lists.infradead.org; Tue, 11 Jul 2023 07:00:54 +0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1689058848; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=v7BjYj/I+4PNhxODpnsSg7iMK5tRoeIrCo2+55CRjhI=; b=F5lmZSA6WJgA2xcJDkDo9gI8agt9MZD4SNf2LRDA4CVWq2zYFUxmghPXa+4LAc56Lq/fuH Z1Tk8A/2vT+PKfDdCHGKy7knNw3fs7VWqLKX8Di8F4o6+cgfp3rr1hV00YwuW+qjuNwkof 1oUO+2iriw38WRy1t7KmwM1QkUWxUxY= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-26-PfcYMSaXMaKpVE0zvE3fRA-1; Tue, 11 Jul 2023 03:00:45 -0400 X-MC-Unique: PfcYMSaXMaKpVE0zvE3fRA-1 Received: from smtp.corp.redhat.com (int-mx09.intmail.prod.int.rdu2.redhat.com [10.11.54.9]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 2F6FA856506; Tue, 11 Jul 2023 07:00:44 +0000 (UTC) Received: from localhost (ovpn-12-93.pek2.redhat.com [10.72.12.93]) by smtp.corp.redhat.com (Postfix) with ESMTPS id B333A492B01; Tue, 11 Jul 2023 07:00:05 +0000 (UTC) Date: Tue, 11 Jul 2023 14:59:35 +0800 From: Baoquan He To: Ming Lei Cc: Christoph Hellwig , Jens Axboe , linux-nvme@lists.infradead.org, linux-block@vger.kernel.org, Wen Xiong , Keith Busch , Dave Young , kexec@lists.infradead.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linuxppc-dev@lists.ozlabs.org, mpe@ellerman.id.au, Thomas Gleixner Subject: Re: [PATCH 2/2] nvme-pci: use blk_mq_max_nr_hw_queues() to calculate io queues Message-ID: References: <20230708020259.1343736-1-ming.lei@redhat.com> <20230708020259.1343736-3-ming.lei@redhat.com> <20230710064109.GB24519@lst.de> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: X-Scanned-By: MIMEDefang 3.1 on 10.11.54.9 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20230711_000053_241197_6BF82AAB X-CRM114-Status: GOOD ( 31.73 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 07/11/23 at 11:53am, Ming Lei wrote: > Hi Baoquan, > > On Tue, Jul 11, 2023 at 11:35:50AM +0800, Baoquan He wrote: > > On 07/10/23 at 05:14pm, Ming Lei wrote: > > > On Mon, Jul 10, 2023 at 08:41:09AM +0200, Christoph Hellwig wrote: > > > > On Sat, Jul 08, 2023 at 10:02:59AM +0800, Ming Lei wrote: > > > > > Take blk-mq's knowledge into account for calculating io queues. > > > > > > > > > > Fix wrong queue mapping in case of kdump kernel. > > > > > > > > > > On arm and ppc64, 'maxcpus=1' is passed to kdump command line, see > > > > > `Documentation/admin-guide/kdump/kdump.rst`, so num_possible_cpus() > > > > > still returns all CPUs. > > > > > > > > That's simply broken. Please fix the arch code to make sure > > > > it does not return a bogus num_possible_cpus value for these > > > > > > That is documented in Documentation/admin-guide/kdump/kdump.rst. > > > > > > On arm and ppc64, 'maxcpus=1' is passed for kdump kernel, and "maxcpu=1" > > > simply keep one of CPU cores as online, and others as offline. > > > > I don't know maxcpus on arm and ppc64 well. But maxcpus=1 or nr_cpus=1 > > are suggested parameter. Because usually nr_cpus=1 is enough to make > > kdump kernel work well to capture vmcore. However, user is allowed to > > specify nr_cpus=n (n>1) if they think multiple cpus are needed in kdump > > kernel. Your hard coding of cpu number in kdump kernel may be not so > > reasonable. > > As I mentioned, for arm/ppc64, passing 'maxcpus=1' actually follows > Documentation/admin-guide/kdump/kdump.rst. > > 'nr_cpus=N' just works fine, so not related with this topic. > > After 'maxcpus=1' is passed, kernel only brings up one of cpu cores as > online during booting, and others still can be put into online by > userspace. Now this way causes IO timeout on some storage device which > uses managed irq and supports multiple io queues. > > Here the focus is if passing 'maxcpus=1' is valid for kdump > kernel, that is we want to hear from our arch/kdump guys. Yes, 'maxcpus=1' is valid and suggested on ppc64 for kdump kernel if needed, because there's no 'nr_cpus=' support on ppc64 yet. > > If yes, something needs to be fixed, such as, what this patchset is > doing. > > > > > Please cc kexec mailing list when posting so that people can view the > > whole thread of discussion. > > Already Cc kexe & arm/powerpc & irq list. > > > Thanks, > Ming > _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel