From owner-freebsd-hackers@FreeBSD.ORG Mon Mar 9 21:03:50 2015 Return-Path: Delivered-To: freebsd-hackers@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [8.8.178.115]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by hub.freebsd.org (Postfix) with ESMTPS id 7AC4D67C for ; Mon, 9 Mar 2015 21:03:50 +0000 (UTC) Received: from na01-by2-obe.outbound.protection.outlook.com (mail-by2on0055.outbound.protection.outlook.com [207.46.100.55]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-SHA384 (256/256 bits)) (Client CN "mail.protection.outlook.com", Issuer "MSIT Machine Auth CA 2" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 3C8EBD8C for ; Mon, 9 Mar 2015 21:03:49 +0000 (UTC) Received: from DM2PR0801MB0944.namprd08.prod.outlook.com (25.160.131.27) by DM2PR0801MB0944.namprd08.prod.outlook.com (25.160.131.27) with Microsoft SMTP Server (TLS) id 15.1.106.15; Mon, 9 Mar 2015 21:03:47 +0000 Received: from DM2PR0801MB0944.namprd08.prod.outlook.com ([25.160.131.27]) by DM2PR0801MB0944.namprd08.prod.outlook.com ([25.160.131.27]) with mapi id 15.01.0106.007; Mon, 9 Mar 2015 21:03:47 +0000 From: "Pokala, Ravi" To: "freebsd-hackers@freebsd.org" Subject: detecting hyperthreading Thread-Topic: detecting hyperthreading Thread-Index: AQHQWqyImRFHWPGSCkqtx00nVjUfFQ== Date: Mon, 9 Mar 2015 21:03:47 +0000 Message-ID: Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: user-agent: Microsoft-MacOutlook/14.4.8.150116 x-originating-ip: [64.80.217.3] authentication-results: freebsd.org; dkim=none (message not signed) header.d=none; x-microsoft-antispam: UriScan:;BCL:0;PCL:0;RULEID:;SRVR:DM2PR0801MB0944; x-microsoft-antispam-prvs: x-forefront-antispam-report: BMV:1; SFV:NSPM; SFS:(10009020)(6009001)(164054003)(450100001)(2900100001)(122556002)(19580395003)(221733001)(77156002)(92566002)(15975445007)(50986999)(40100003)(66066001)(83506001)(102836002)(36756003)(86362001)(229853001)(62966003)(2656002)(107886001)(46102003)(2351001)(54356999)(106116001)(87936001)(110136001)(2501003); DIR:OUT; SFP:1101; SCL:1; SRVR:DM2PR0801MB0944; H:DM2PR0801MB0944.namprd08.prod.outlook.com; FPR:; SPF:None; MLV:sfv; LANG:en; x-exchange-antispam-report-test: UriScan:; x-exchange-antispam-report-cfa-test: BCL:0; PCL:0; RULEID:(601004)(5005006)(5002009); SRVR:DM2PR0801MB0944; BCL:0; PCL:0; RULEID:; SRVR:DM2PR0801MB0944; x-forefront-prvs: 05102978A2 Content-Type: text/plain; charset="us-ascii" Content-ID: Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 X-OriginatorOrg: panasas.com X-MS-Exchange-CrossTenant-originalarrivaltime: 09 Mar 2015 21:03:47.1221 (UTC) X-MS-Exchange-CrossTenant-fromentityheader: Hosted X-MS-Exchange-CrossTenant-id: acf01c9d-c699-42af-bdbb-44bf582e60b0 X-MS-Exchange-Transport-CrossTenantHeadersStamped: DM2PR0801MB0944 X-BeenThere: freebsd-hackers@freebsd.org X-Mailman-Version: 2.1.18-1 Precedence: list List-Id: Technical Discussions relating to FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 09 Mar 2015 21:03:50 -0000 Hi folks, There used to be a sysctl, "machdep.hyperthreading_allowed", which indicated whether or not the kernel was using hyperthreaded cores. It looks like it was removed sometime between 8 and 9, for perfectly good reasons (https://svnweb.freebsd.org/base?view=3Drevision&revision=3D222853)= . That said, is there currently a way to tell at runtime from userland if hyperthreading is enabled or not? Thanks, Ravi