From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from mail-pg0-x244.google.com ([2607:f8b0:400e:c05::244]) by bombadil.infradead.org with esmtps (Exim 4.89 #1 (Red Hat Linux)) id 1evFJC-0001Gn-FR for kexec@lists.infradead.org; Mon, 12 Mar 2018 04:43:45 +0000 Received: by mail-pg0-x244.google.com with SMTP id y26so6047405pgv.4 for ; Sun, 11 Mar 2018 21:43:28 -0700 (PDT) From: Pingfan Liu Subject: [PATCHv4 2/3] powerpc, cpu: handling the special case when boot_cpuid greater than nr_cpus Date: Mon, 12 Mar 2018 12:43:09 +0800 Message-Id: <1520829790-14029-3-git-send-email-kernelfans@gmail.com> In-Reply-To: <1520829790-14029-1-git-send-email-kernelfans@gmail.com> References: <1520829790-14029-1-git-send-email-kernelfans@gmail.com> List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "kexec" Errors-To: kexec-bounces+dwmw2=infradead.org@lists.infradead.org To: linuxppc-dev@lists.ozlabs.org Cc: cascardo@canonical.com, gpiccoli@linux.vnet.ibm.com, kexec@lists.infradead.org, paulus@ozlabs.org, mpe@ellerman.id.au, benh@kernel.crashing.org For kexec -p, after boot_cpuid is mapping into the range of [0, threads_per_core), then if nr_cpus is small, we will have the bitmap [0,..., nr_cpus, ..., boot_cpuid, ...). This patch chooses cpus inside the range of [boot_cpuid - nr_cpus +1, ..., boot_cpuid] to be online. With this patch and the next, on a P9 machine with thread_per_core=4, and set nr_cpus=2 for the crash kernel. After taskset -c 11 sh -c "echo c > /proc/sysrq-trigger" Then kdump:/sys/devices/system/cpu# cat possible 2-3 kdump:/sys/devices/system/cpu# cat present 2-3 kdump:/sys/devices/system/cpu# cat online 2-3 Signed-off-by: Pingfan Liu --- arch/powerpc/kernel/setup-common.c | 14 ++++++++++++-- 1 file changed, 12 insertions(+), 2 deletions(-) diff --git a/arch/powerpc/kernel/setup-common.c b/arch/powerpc/kernel/setup-common.c index 1a67344..6920b5e 100644 --- a/arch/powerpc/kernel/setup-common.c +++ b/arch/powerpc/kernel/setup-common.c @@ -462,6 +462,8 @@ void __init smp_setup_cpu_maps(void) struct device_node *dn; struct device_node *boot_dn = NULL; bool handling_bootdn = true; + int head_thread = 0; + int online_cnt = 0; int cpu = 0; int nthreads = 1; @@ -499,13 +501,19 @@ void __init smp_setup_cpu_maps(void) if (boot_cpuid < nthreads && be32_to_cpu(intserv[boot_cpuid]) == boot_cpuhwid) { boot_dn = dn; + /* choose a bunch of continous threads */ + if (boot_cpuid > nr_cpu_ids - 1) { + head_thread = boot_cpuid - nr_cpu_ids + 1; + /* keep the mapping of logical and thread */ + cpu = head_thread; + } } if (boot_dn == NULL) continue; } else if (dn == boot_dn) continue; - for (j = 0; j < nthreads && cpu < nr_cpu_ids; j++) { + for (j = head_thread; j < nthreads && online_cnt < nr_cpu_ids; j++) { bool avail; DBG(" thread %d -> cpu %d (hard id %d)\n", @@ -520,13 +528,15 @@ void __init smp_setup_cpu_maps(void) set_hard_smp_processor_id(cpu, be32_to_cpu(intserv[j])); set_cpu_possible(cpu, true); cpu++; + online_cnt++; } - if (cpu >= nr_cpu_ids) { + if (online_cnt >= nr_cpu_ids) { of_node_put(dn); break; } if (handling_bootdn) { + head_thread = 0; handling_bootdn = false; goto again; } -- 2.7.4 _______________________________________________ kexec mailing list kexec@lists.infradead.org http://lists.infradead.org/mailman/listinfo/kexec