From owner-freebsd-questions@FreeBSD.ORG Mon Aug 29 21:20:48 2011 Return-Path: Delivered-To: questions@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 80EAC106564A for ; Mon, 29 Aug 2011 21:20:48 +0000 (UTC) (envelope-from amvandemore@gmail.com) Received: from mail-fx0-f54.google.com (mail-fx0-f54.google.com [209.85.161.54]) by mx1.freebsd.org (Postfix) with ESMTP id 165D88FC13 for ; Mon, 29 Aug 2011 21:20:47 +0000 (UTC) Received: by fxe4 with SMTP id 4so6261047fxe.13 for ; Mon, 29 Aug 2011 14:20:46 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :cc:content-type; bh=EJEqqowYPNliaS4z0wZfSRViwjmlfEy6AUK7YoIdaNM=; b=SKRZ3eMLTKrZ9aQIGqf6lc/P0WdvfvERIVNaSjzss4Y4bRCzw3Zn7KOXtaT+VTHwVE lvvBapp0uLgWegDLPUu6BoelRObpOia5l67fAPagkbX1QzGayHI3JetupZHOvDDYwKzO Kw5AERbFMeQuSZjtqfQ2IEznSczo+rXRAWsYM= MIME-Version: 1.0 Received: by 10.223.26.20 with SMTP id b20mr7103902fac.50.1314652846630; Mon, 29 Aug 2011 14:20:46 -0700 (PDT) Received: by 10.223.120.72 with HTTP; Mon, 29 Aug 2011 14:20:46 -0700 (PDT) In-Reply-To: <201108292115.PAA21491@lariat.net> References: <201108291724.LAA18734@lariat.net> <4E5BEE9C.7080706@cran.org.uk> <201108292115.PAA21491@lariat.net> Date: Mon, 29 Aug 2011 16:20:46 -0500 Message-ID: From: Adam Vande More To: Brett Glass Content-Type: text/plain; charset=ISO-8859-1 X-Content-Filtered-By: Mailman/MimeDel 2.1.5 Cc: Bruce Cran , questions@freebsd.org Subject: Re: Turn off hyperthreading on dual core Atom? X-BeenThere: freebsd-questions@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: User questions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 29 Aug 2011 21:20:48 -0000 On Mon, Aug 29, 2011 at 4:15 PM, Brett Glass wrote > Alas, during a recent kernel build, I used the -j2 command line option in > "make" and watched as the scheduler repeatedly assigned two instances of cc > (the most CPU-intensive program) to the same core. > > During that process, I also watched CPU utilization in top(1). The peak was > 46% idle, which means that HTT appeared to be making at most a 4% > difference. (If the peak were 50% idle, HTT would be doing nothing at all, > because top(1) can't tell that there aren't really 4 CPUs.) > You can achieve definitive answers by timing several build runs of each setting and using ministat. -- Adam Vande More