From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753023AbYLQWOr (ORCPT ); Wed, 17 Dec 2008 17:14:47 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751651AbYLQWOg (ORCPT ); Wed, 17 Dec 2008 17:14:36 -0500 Received: from relay3.sgi.com ([192.48.171.31]:40168 "EHLO relay.sgi.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751360AbYLQWOf (ORCPT ); Wed, 17 Dec 2008 17:14:35 -0500 Message-ID: <494979C6.7060003@sgi.com> Date: Wed, 17 Dec 2008 14:14:30 -0800 From: Mike Travis User-Agent: Thunderbird 2.0.0.6 (X11/20070801) MIME-Version: 1.0 To: Greg KH , Rusty Russell CC: Ingo Molnar , Jack Steiner , linux-kernel@vger.kernel.org, Ben Hutchings Subject: [PATCH 1/1]: sysfs: add documentation to cputopology.txt for system cpumasks References: <20081216042645.629941000@polaris-admin.engr.sgi.com> <20081216042646.088194000@polaris-admin.engr.sgi.com> <200812172223.53079.rusty@rustcorp.com.au> <20081217184011.GB30724@suse.de> In-Reply-To: <20081217184011.GB30724@suse.de> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Subject: sysfs: add documentation to cputopology.txt for system cpumasks Add information to cputopology.txt explaining the output of various system cpumask's. Signed-off-by: Mike Travis --- Documentation/cputopology.txt | 48 ++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 48 insertions(+) --- linux-2.6-for-ingo.orig/Documentation/cputopology.txt +++ linux-2.6-for-ingo/Documentation/cputopology.txt @@ -31,3 +31,51 @@ not defined by include/asm-XXX/topology. 2) core_id: 0 3) thread_siblings: just the given CPU 4) core_siblings: just the given CPU + +Additionally, cpu topology information is provided under +/sys/devices/system/cpu and includes these files. The internal +source for the output is in brackets ("[]"). + + kernel_max: the maximum cpu index allowed by the kernel configuration. + [NR_CPUS-1] + + offline: cpus that are not online because they have been + HOTPLUGGED off (see cpu-hotplug.txt) or exceed the limit + of cpus allowed by the kernel configuration (kernel_max + above). [~cpu_online_mask + cpus >= NR_CPUS] + + online: cpus that are online and being scheduled [cpu_online_mask] + + possible: cpus that have been allocated resources and can be + brought online if they are present. [cpu_possible_mask] + + present: cpus that have been identified as being present in the + system. [cpu_present_mask] + +The format for the above output is compatible with cpulist_parse() +[see ]. Some examples follow. + +In this example, there are 64 cpus in the system but cpus 32-63 exceed +the kernel max which is limited to 0..31 by the NR_CPUS config option +being 32. Note also that cpus 2 and 4-31 are not online but could be +brought online as they are both present and possible. + + kernel_max: 31 + offline: 2,4-31,32-63 + online: 0-1,3 + possible: 0-31 + present: 0-31 + +In this example, the NR_CPUS config option is 128, but the kernel was +started with possible_cpus=144. There are 4 cpus in the system and cpu2 +was manually taken offline (and is the only cpu that can be brought +online.) + + kernel_max: 127 + offline: 2,4-127,128-143 + online: 0-1,3 + possible: 0-127 + present: 0-3 + +See cpu-hotplug.txt for the possible_cpus=NUM kernel start parameter +as well as more information on the various cpumask's.