Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1030816AbbD1TSs (ORCPT ); Tue, 28 Apr 2015 15:18:48 -0400 Received: from mail-am1on0054.outbound.protection.outlook.com ([157.56.112.54]:59104 "EHLO emea01-am1-obe.outbound.protection.outlook.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1030638AbbD1TSr (ORCPT ); Tue, 28 Apr 2015 15:18:47 -0400 Authentication-Results: linuxfoundation.org; dkim=none (message not signed) header.d=none; Message-ID: <553FDD06.8090504@ezchip.com> Date: Tue, 28 Apr 2015 15:18:30 -0400 From: Chris Metcalf User-Agent: Mozilla/5.0 (X11; Linux i686 on x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.6.0 MIME-Version: 1.0 To: , CC: , , , , Subject: Re: [PATCH 2/2] show nohz_full cpus in sysfs References: <1429903468-11099-1-git-send-email-riel@redhat.com> <1429903468-11099-3-git-send-email-riel@redhat.com> In-Reply-To: <1429903468-11099-3-git-send-email-riel@redhat.com> Content-Type: text/plain; charset="windows-1252"; format=flowed Content-Transfer-Encoding: 7bit X-Originating-IP: [12.216.194.146] X-ClientProxiedBy: BY1PR0201CA0041.namprd02.prod.outlook.com (25.160.191.179) To AM2PR02MB0771.eurprd02.prod.outlook.com (25.163.146.156) X-Microsoft-Antispam: UriScan:;BCL:0;PCL:0;RULEID:;SRVR:AM2PR02MB0771; X-Forefront-Antispam-Report: BMV:1;SFV:NSPM;SFS:(10009020)(6009001)(6049001)(377454003)(479174004)(51704005)(24454002)(76176999)(19580405001)(62966003)(83506001)(54356999)(65816999)(2950100001)(87266999)(23746002)(46102003)(50466002)(19580395003)(77156002)(86362001)(15975445007)(33656002)(59896002)(64126003)(92566002)(5001770100001)(42186005)(47776003)(66066001)(36756003)(50986999)(87976001)(77096005)(4001350100001)(122386002)(65956001)(40100003)(65806001)(18886065003);DIR:OUT;SFP:1101;SCL:1;SRVR:AM2PR02MB0771;H:[10.7.0.41];FPR:;SPF:None;MLV:sfv;LANG:en; X-Microsoft-Antispam-PRVS: X-Exchange-Antispam-Report-Test: UriScan:; X-Exchange-Antispam-Report-CFA-Test: BCL:0;PCL:0;RULEID:(601004)(5002010)(5005006)(3002001);SRVR:AM2PR02MB0771;BCL:0;PCL:0;RULEID:;SRVR:AM2PR02MB0771; X-Forefront-PRVS: 0560A2214D X-OriginatorOrg: ezchip.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 28 Apr 2015 19:18:42.1557 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-Transport-CrossTenantHeadersStamped: AM2PR02MB0771 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1208 Lines: 32 On 04/24/2015 03:24 PM, riel@redhat.com wrote: > From: Rik van Riel > > Currently there is no way to query which CPUs are in nohz_full > mode from userspace. > > Export the CPU list running in nohz_full mode in sysfs, > specifically in the file /sys/devices/system/cpu/nohz_full > > This can be used by system management tools like libvirt, > openstack, and others to ensure proper task placement. > > Signed-off-by: Rik van Riel > --- > drivers/base/cpu.c | 17 +++++++++++++++++ > 1 file changed, 17 insertions(+) In the arch/tile distribution with our "dataplane" support, we have traditionally had a /sys/devices/system/cpu/dataplane file with the same semantics you are proposing. It's definitely helpful to userspace applications figuring out how to appropriately take over the machine they are being run on. Acked-by: Chris Metcalf -- Chris Metcalf, EZChip Semiconductor http://www.ezchip.com -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/