Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Mon, 29 Apr 2002 15:40:53 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Mon, 29 Apr 2002 15:40:51 -0400 Received: from jffdns02.or.intel.com ([134.134.248.4]:49631 "EHLO hebe.or.intel.com") by vger.kernel.org with ESMTP id ; Mon, 29 Apr 2002 15:40:49 -0400 Message-ID: <59885C5E3098D511AD690002A5072D3C02AB7DF0@orsmsx111.jf.intel.com> From: "Grover, Andrew" To: "'Andrew Theurer'" , linux-kernel@vger.kernel.org Subject: RE: Hyperthreading and physical/logical CPU identification Date: Mon, 29 Apr 2002 12:40:42 -0700 MIME-Version: 1.0 X-Mailer: Internet Mail Service (5.5.2653.19) Content-Type: text/plain Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org > From: Andrew Theurer [mailto:habanero@us.ibm.com] > I would like to know if there is any way to confirm that I have > hyperthreading enabled, and my P4 CPUs are hyperthreaded. > Actually, from > something like /proc/cpuinfo, I'd like to figure out if I am > seeing 2/4 > physical/logical processors, as a result from hyperthreading, or 4/4 > physical/logical processors with no hyperthreading. I know, > "If it's double > the number of physical processors, well you have > hyperthreading enabled." > The problem is, I have 4 physical processors, but kernel.org > kernels so far > do not recognize all of them. 2.4.18 will find 3, while > 2.5.11 will find > only 2 (BIOS hyperthreading support off, no acpismp=force). > However, on > 2.5.11, if I enable hyperthreading (thru BIOS and > acpismp=force, I see 4 > processors. > > I would very much like to believe that in this configuration, > I am only > running on 2 physical, 4 logical processors, but I am getting a 31% > improvement (netbench) when hyperthreading is enabled. Thats > why I want to > confirm I am really only using 2 physical, 4 logical > processors. Is there > any way I can do this? (dmesg? /proc/cpuinfo?) Well the two alternatives are, either A) turning on hyperthreading enabled the two virtual processors or B) turning on hyperthreading somehow enabled the other two processors, right? I would think B would be highly unlikely. Anyone else who actually has HT hardware care to comment? ;-) Regards -- Andy - 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/