From owner-freebsd-stable@FreeBSD.ORG Thu May 4 21:54:28 2006 Return-Path: X-Original-To: freebsd-stable@freebsd.org Delivered-To: freebsd-stable@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id BE2B016A403 for ; Thu, 4 May 2006 21:54:28 +0000 (UTC) (envelope-from noackjr@alumni.rice.edu) Received: from mail.clickfox.com (cffw1.clickfox.com [72.16.213.34]) by mx1.FreeBSD.org (Postfix) with ESMTP id 418A843D45 for ; Thu, 4 May 2006 21:54:28 +0000 (GMT) (envelope-from noackjr@alumni.rice.edu) X-PMWin-Spam: Gauge=IIIIIIII, Probability=8%, Report='__HAS_MSGID, __SANE_MSGID, __USER_AGENT, __MIME_VERSION, __CT, __CTYPE_CHARSET_QUOTED, __CT_TEXT_PLAIN, __CTE, __MIME_TEXT_ONLY' Thread-Index: AcZvxffXD2Nyd/WRTgS+Nl8mAnSISw== X-PMWin-Version: 2.5.1s, Antispam-Engine: 2.3.0.1, Antivirus-Engine: 2.32.14 Received: from [10.20.30.156] ([72.16.213.34]) by mail.clickfox.com over TLS secured channel with Microsoft SMTPSVC(6.0.3790.1830); Thu, 4 May 2006 17:59:08 -0400 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.3790.2663 Content-class: urn:content-classes:message Importance: normal Priority: normal Message-ID: <445A7810.5010702@alumni.rice.edu> Date: Thu, 04 May 2006 17:54:24 -0400 From: "Jonathan Noack" User-Agent: Thunderbird 1.5.0.2 (Windows/20060308) MIME-Version: 1.0 To: "Marc G. Fournier" References: <20060503113955.U1147@ganymede.hub.org> In-reply-to: <20060503113955.U1147@ganymede.hub.org> Content-Type: text/plain; format=flowed; charset="ISO-8859-1" Content-Transfer-Encoding: 7bit X-OriginalArrivalTime: 04 May 2006 21:59:08.0288 (UTC) FILETIME=[F7C6D000:01C66FC5] Cc: freebsd-stable@freebsd.org Subject: Re: Hyperthreading in 6.x ... still frowned upon? X-BeenThere: freebsd-stable@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list Reply-To: noackjr@alumni.rice.edu List-Id: Production branch of FreeBSD source code List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 04 May 2006 21:54:28 -0000 Marc G. Fournier wrote: > In 4.x, it was a 'shut it off' sort of deal .. my new amd64 don't appear > to have it enabled, but my older i386 server that I just upgraded to 6.x > does: > > user pid %cpu %mem vsz rss tt state start time command > root 14 104.0 0.0 0 8 ?? RL 11:38AM 0:55.02 [idle: > cpu0] > root 11 99.1 0.0 0 8 ?? RL 11:38AM 0:00.00 [idle: > cpu3] > root 13 99.1 0.0 0 8 ?? RL 11:38AM 0:00.00 [idle: > cpu1] > root 12 98.0 0.0 0 8 ?? RL 11:38AM 0:54.54 [idle: > cpu2] > > Is it still something that I should disable, and, if so, how in 6.x? According to the 6.0 i386 Release Notes, you should use the machdep.hyperthreading_allowed sysctl to disable Hyper-Threading. If you are concerned with security, you should disable it. If you are more concerned with performance, you should test your workload with/without Hyper-Threading and choose the configuration which performs best. -Jonathan