From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx0b-00082601.pphosted.com ([67.231.153.30]:48626 "EHLO mx0b-00082601.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751913AbcAYPap (ORCPT ); Mon, 25 Jan 2016 10:30:45 -0500 Subject: Re: [FIO][PATCH v1] powerpc: fix cpus_online() to get correct max CPU number for powerpc64 References: <1453727058-45619-1-git-send-email-dqzhang@linux.vnet.ibm.com> From: Jens Axboe Message-ID: <56A63F91.6090102@fb.com> Date: Mon, 25 Jan 2016 08:30:25 -0700 MIME-Version: 1.0 In-Reply-To: <1453727058-45619-1-git-send-email-dqzhang@linux.vnet.ibm.com> Content-Type: text/plain; charset="windows-1252"; format=flowed Content-Transfer-Encoding: 7bit Sender: fio-owner@vger.kernel.org List-Id: fio@vger.kernel.org To: Dan Qing Zhang Cc: fio@vger.kernel.org, zhong@linux.vnet.ibm.com On 01/25/2016 06:04 AM, Dan Qing Zhang wrote: > This patch tries to fix cpus_online() for powerpc64 when running fio > by using parameter "cpus_allowed", in order to obtain correct max CPU > number on powerpc64 architecture. > > When changing SMT settings on powerpc architecture, the way of cpu > numbering is changing as well. For example, when SMT=off, CPUs are > numbered like 0,8,16,..., while when SMT=2, CPUs are numbered like > 0,1,8,9,.... Therefore, sysconf(_SC_NPROCESSORS_ONLN) is not applied > to get exact max CPU number on powerpc. And the max_cpu value can be > correctly ontained by using sysconf(_SC_NPROCESSORS_CONF). Thanks, applied. I have a general dislike for discontiguous CPU numbering, be it in the kernel or in user space :-) -- Jens Axboe