Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755628AbZKEDQ5 (ORCPT ); Wed, 4 Nov 2009 22:16:57 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753910AbZKEDQ4 (ORCPT ); Wed, 4 Nov 2009 22:16:56 -0500 Received: from mail-yx0-f187.google.com ([209.85.210.187]:43782 "EHLO mail-yx0-f187.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750848AbZKEDQz (ORCPT ); Wed, 4 Nov 2009 22:16:55 -0500 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=subject:from:to:cc:in-reply-to:references:content-type:date :message-id:mime-version:x-mailer:content-transfer-encoding; b=fJNzx06p1pBN7DPziWwFmgh4YesqMh9fsHuplP9BMdDCbx3n4uUFuV9rMB0gUcYt7r 6g+t2zKymsHUXu1z/Q4Cf/vlJkADbkAyOBgS8U9CSkrwscVig5zC2LQcXxe4jeHp/kOD vYd+3aLkh+0as333795ofq9ESaDbVpidVTkg0= Subject: Re: Is this needed to enable turbo mode/boost on i7 processors? From: Calvin Walton To: Justin Piszcz Cc: linux-kernel@vger.kernel.org In-Reply-To: References: Content-Type: text/plain; charset="UTF-8" Date: Wed, 04 Nov 2009 22:16:56 -0500 Message-ID: <1257391016.9724.11.camel@nayuki> Mime-Version: 1.0 X-Mailer: Evolution 2.28.1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1790 Lines: 51 On Tue, 2009-11-03 at 16:00 -0500, Justin Piszcz wrote: > I realize the BIOS is supposed to take care of it, but it would be nice if > there was an easy way to verify it is working. > > On Tue, 3 Nov 2009, Justin Piszcz wrote: > > > Hello, > > > > Per: http://kolbusa.livejournal.com/71066.html > > > > Is it necessary to do this--? > > > > Is there a way to verify whether turbo boost is being enabled when one core > > is at 100% cpu? > > > > Justin. Assuming that the cpufreq functionality is enabled in your kernel, a simple cat /sys/devices/system/cpu/cpu*/cpufreq/scaling_cur_freq Should return the frequencies that each cpu core is currently running at. I'm using a core i7 920 (2.67 ghz nominal) and have seen it hit 2.80 ghz on occasion. None of the extra kernel options mentioned in that blog post should be required, assuming that you are using an up-to-date kernel. I would expect this to work correctly in the latest Ubuntu or Fedora, for example. For the record, I have all of the bios power saving modes enabled (and turbo mode, of course), and am using the kernel 'ondemand' governor with no extra userspace applications or configuration. My understanding of how it works is that when the cpu load is OK, the bios adjusts the values for the top couple of speedstep settings (use cat /sys/devices/system/cpu/cpu*/cpufreq/scaling_available_frequencies to see them), and the kernel will automatically take advantage of them, according to the cpufreq governor you select. -- Calvin Walton -- 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/