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 31EBECD98E9 for ; Wed, 11 Oct 2023 03:05:45 +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=YndxWFpwM+jc/Ck8jHYd20j/Tv1NLHb1us6BonGPNRU=; b=ybCLCew4+Y0PAQ D6CSxs7pYp0g7RFWf+R/awfO+KNEtQk1FKwhkXKqWh+VnpfZQBa3r08biyY5rTxaWwOn4vwGD9aC4 cl3vLADf6RTHf7DNqWFcirpYtoRXuYZy3vKKYBkbkJEsY5h8LR2cIfaZ+8JwtPWnN4YeY7pBrC9r/ JP0+PYaIxoG1czeo0eck6VVU6azVnGZ2/c911ECrZDmed0Neud+ztWCNmtJY2PhS2G5TKHx0Td0vl z9SGSjHIMjmUiBLySmovg8XTHNqGOzwSO+eYuDMNnP/h1nRDnfFGCZURJUpYxAm/Adp3h8COpvV3G HD1Gm7J5Wzw+O8fJ8lAA==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.96 #2 (Red Hat Linux)) id 1qqPXa-00EdQc-0p; Wed, 11 Oct 2023 03:05:42 +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 1qqPXX-00EdQ4-1F for kexec@lists.infradead.org; Wed, 11 Oct 2023 03:05:40 +0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1696993538; 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=AvOLEprUT3mwclaqpVcqIEF1+DoeNmmz2gHww9Z9kLg=; b=iGwuDmrKwZxGEZmeQGfGKv8mt2jHH+K6W0jTgvxNxghAW9u61XobREJfw5hg3RDsY1T/G5 c+MqlBcc2s6kazcI80MxVq4sjv92BQWy41FG3ylVdJkgb93MMt54yFdGCdnFfsiOuTopQ3 BqXckbb6yyutqk86S1JnUknnyDWAO54= Received: from mimecast-mx02.redhat.com (mx-ext.redhat.com [66.187.233.73]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-336-ss5hYIS7PfysupHzS3n9rA-1; Tue, 10 Oct 2023 23:05:36 -0400 X-MC-Unique: ss5hYIS7PfysupHzS3n9rA-1 Received: from smtp.corp.redhat.com (int-mx10.intmail.prod.int.rdu2.redhat.com [10.11.54.10]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id B969C3C0DF84; Wed, 11 Oct 2023 03:05:35 +0000 (UTC) Received: from piliu.users.ipa.redhat.com (unknown [10.72.120.9]) by smtp.corp.redhat.com (Postfix) with ESMTPS id CF8A6492C3E; Wed, 11 Oct 2023 03:05:31 +0000 (UTC) Date: Wed, 11 Oct 2023 11:05:26 +0800 From: Pingfan Liu To: Hari Bathini Cc: linuxppc-dev@lists.ozlabs.org, Baoquan He , kexec@lists.infradead.org, Mahesh Salgaonkar , Nicholas Piggin , Ming Lei , Wen Xiong Subject: Re: [PATCHv8 3/5] powerpc/setup: Handle the case when boot_cpuid greater than nr_cpus Message-ID: References: <20231009113036.45988-1-piliu@redhat.com> <20231009113036.45988-4-piliu@redhat.com> <8216e3e3-8475-158f-dc79-1b5ba1032150@linux.ibm.com> MIME-Version: 1.0 In-Reply-To: <8216e3e3-8475-158f-dc79-1b5ba1032150@linux.ibm.com> X-Scanned-By: MIMEDefang 3.1 on 10.11.54.10 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Disposition: inline X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20231010_200539_493948_1DBED98E X-CRM114-Status: GOOD ( 26.55 ) X-BeenThere: kexec@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: "kexec" Errors-To: kexec-bounces+kexec=archiver.kernel.org@lists.infradead.org On Tue, Oct 10, 2023 at 01:56:13PM +0530, Hari Bathini wrote: > > > On 09/10/23 5:00 pm, Pingfan Liu wrote: > > If the boot_cpuid is smaller than nr_cpus, it requires extra effort to > > ensure the boot_cpu is in cpu_present_mask. This can be achieved by > > reserving the last quota for the boot cpu. > > > > Note: the restriction on nr_cpus will be lifted with more effort in the > > successive patches > > > > Signed-off-by: Pingfan Liu > > Cc: Michael Ellerman > > Cc: Nicholas Piggin > > Cc: Christophe Leroy > > Cc: Mahesh Salgaonkar > > Cc: Wen Xiong > > Cc: Baoquan He > > Cc: Ming Lei > > Cc: kexec@lists.infradead.org > > To: linuxppc-dev@lists.ozlabs.org > > --- > > arch/powerpc/kernel/setup-common.c | 25 ++++++++++++++++++++++--- > > 1 file changed, 22 insertions(+), 3 deletions(-) > > > > diff --git a/arch/powerpc/kernel/setup-common.c b/arch/powerpc/kernel/setup-common.c > > index 81291e13dec0..f9ef0a2666b0 100644 > > --- a/arch/powerpc/kernel/setup-common.c > > +++ b/arch/powerpc/kernel/setup-common.c > > @@ -454,8 +454,8 @@ struct interrupt_server_node { > > void __init smp_setup_cpu_maps(void) > > { > > struct device_node *dn; > > - int shift = 0, cpu = 0; > > - int j, nthreads = 1; > > + int terminate, shift = 0, cpu = 0; > > + int j, bt_thread = 0, nthreads = 1; > > int len; > > struct interrupt_server_node *intserv_node, *n; > > struct list_head *bt_node, head; > > @@ -518,6 +518,7 @@ void __init smp_setup_cpu_maps(void) > > for (j = 0 ; j < nthreads; j++) { > > if (be32_to_cpu(intserv[j]) == boot_cpu_hwid) { > > bt_node = &intserv_node->node; > > + bt_thread = j; > > found_boot_cpu = true; > > /* > > * Record the round-shift between dt > > @@ -537,11 +538,21 @@ void __init smp_setup_cpu_maps(void) > > /* Select the primary thread, the boot cpu's slibing, as the logic 0 */ > > list_add_tail(&head, bt_node); > > pr_info("the round shift between dt seq and the cpu logic number: %d\n", shift); > > + terminate = nr_cpu_ids; > > list_for_each_entry(intserv_node, &head, node) { > > + j = 0; > > > + /* Choose a start point to cover the boot cpu */ > > + if (nr_cpu_ids - 1 < bt_thread) { > > + /* > > + * The processor core puts assumption on the thread id, > > + * not to breach the assumption. > > + */ > > + terminate = nr_cpu_ids - 1; > > nthreads is anyway assumed to be same for all cores. So, enforcing > nr_cpu_ids to a minimum of nthreads (and multiple of nthreads) should > make the code much simpler without the need for above check and the > other complexities addressed in the subsequent patches... > Indeed, this series can be splited into two partsk, [1-2/5] and [3-5/5]. In [1-2/5], if smaller, the nr_cpu_ids is enforced to be equal to nthreads. I will make it align upward on nthreads in the next version. So [1-2/5] can be totally independent from the rest patches in this series. >From an engineer's perspective, [3-5/5] are added to maintain the nr_cpus semantics. (Finally, nr_cpus=1 can be achieved but requiring effort on other subsystem) Testing result on my Power9 machine with SMT=4 -1. taskset -c 4 bash -c 'echo c > /proc/sysrq-trigger' kdump:/# cat /proc/meminfo | grep Percpu Percpu: 896 kB kdump:/# cat /sys/devices/system/cpu/possible 0 -2. taskset -c 5 bash -c 'echo c > /proc/sysrq-trigger' kdump:/# cat /proc/meminfo | grep Percpu Percpu: 1792 kB kdump:/# cat /sys/devices/system/cpu/possible 0-1 -3. taskset -c 6 bash -c 'echo c > /proc/sysrq-trigger' kdump:/# cat /proc/meminfo | grep Percpu Percpu: 1792 kB kdump:/# cat /sys/devices/system/cpu/possible 0,2 -4. taskset -c 7 bash -c 'echo c > /proc/sysrq-trigger' kdump:/# cat /proc/meminfo | grep Percpu Percpu: 1792 kB kdump:/# cat /sys/devices/system/cpu/possible 0,3 Thanks, Pingfan _______________________________________________ kexec mailing list kexec@lists.infradead.org http://lists.infradead.org/mailman/listinfo/kexec