From owner-freebsd-questions@FreeBSD.ORG Fri Jan 13 18:33:54 2012 Return-Path: Delivered-To: freebsd-questions@FreeBSD.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id E017E106564A for ; Fri, 13 Jan 2012 18:33:54 +0000 (UTC) (envelope-from bf1783@googlemail.com) Received: from mail-ww0-f50.google.com (mail-ww0-f50.google.com [74.125.82.50]) by mx1.freebsd.org (Postfix) with ESMTP id 7701F8FC0A for ; Fri, 13 Jan 2012 18:33:54 +0000 (UTC) Received: by wgbdr11 with SMTP id dr11so3652675wgb.31 for ; Fri, 13 Jan 2012 10:33:53 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=googlemail.com; s=gamma; h=mime-version:reply-to:date:message-id:subject:from:to:content-type; bh=WGtr+aRd3Fj1y+GP1wGEyLJDXllq3zaEiXRr+oW6bj0=; b=Fp9pePGUE8iP9bzf9v5mEMdWjXUHx/LCIFh0Bu3EcGMpFRGm62T2AUQJBtr+ioTn3V Bz1n3NezDKvlf1DX810UXw5Y7AfQFlm1rvev7nn7VpbP+IEyzbrr1/1ePAFszLwBv7rv pU1GTzHlVZJDoxF5eIfnKVn+PIgFVqqQNFxmg= MIME-Version: 1.0 Received: by 10.216.202.194 with SMTP id d44mr1115459weo.1.1326478104355; Fri, 13 Jan 2012 10:08:24 -0800 (PST) Received: by 10.180.94.6 with HTTP; Fri, 13 Jan 2012 10:08:24 -0800 (PST) Date: Fri, 13 Jan 2012 18:08:24 +0000 Message-ID: From: "b. f." To: Marco Beishuizen , Mark Blackman , freebsd-questions@FreeBSD.org Content-Type: text/plain; charset=ISO-8859-1 Cc: Subject: Re: no hyperthreading in FreeBSD 9? X-BeenThere: freebsd-questions@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list Reply-To: bf1783@gmail.com List-Id: User questions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 13 Jan 2012 18:33:55 -0000 > > > Hi, > > > > I just upgraded from 8-STABLE to 9-STABLE on my dual Xeon (nocona). Now I have in my boot messages: > > ... > > root: /etc/rc.d/sysctl: WARNING: sysctl machdep.hlt_logical_cpus does not exist. > > root: /etc/rc.d/sysctl: WARNING: sysctl machdep.hyperthreading_allowed does not exist. > > ... > > > > So isn't hyperthreading not available anymore in FreeBSD 9? I'm not sure what you mean by this double negative. If you mean "Is hyperthreading still available on FreeBSD?", the answer is yes. If you mean "Can hyperthreading still be disabled on FreeBSD?" the answer is still yes-- only some problematic and redundant means of disabling it that were present in earlier versions of FreeBSD have been removed. (The primary commit is: http://svnweb.freebsd.org/base?view=revision&revision=222853 .) You can still use machdep.hyperthreading_allowed, but it is now only a (loader) tunable, and not also a sysctl, so you can only set it at boot time (via loader.conf(5), or by using "set ..." on the loader(8) command line), and you cannot change it on the fly after the system is up and running. > > http://svnweb.freebsd.org/base/release/9.0.0/UPDATING?r1=222852&r2=222853& > > Seems to imply HT is enabled by default and new sysctls are used to take > logical CPUs offline. > Yes -- although that has been the case for a while, and the OIDs are not all sysctls (some are (loader) tunables or device hints (cf. device.hints(5)), and they are not new. b.