From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752695Ab0DSRrr (ORCPT ); Mon, 19 Apr 2010 13:47:47 -0400 Received: from cavan.codon.org.uk ([93.93.128.6]:58462 "EHLO cavan.codon.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751494Ab0DSRrq (ORCPT ); Mon, 19 Apr 2010 13:47:46 -0400 Date: Mon, 19 Apr 2010 18:47:37 +0100 From: Matthew Garrett To: Luming Yu Cc: LKML , Len Brown , "Pallipadi, Venkatesh" , "Siddha, Suresh B" , Arjan van de Ven Subject: Re: [RFC PATCH] use acpi_idle_enter_simple if bm_check && !.bm_control Message-ID: <20100419174737.GA13331@srcf.ucam.org> References: <3877989d0911092212i367b9156n78d57aeee6742147@mail.gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <3877989d0911092212i367b9156n78d57aeee6742147@mail.gmail.com> User-Agent: Mutt/1.5.18 (2008-05-17) X-SA-Exim-Connect-IP: X-SA-Exim-Mail-From: mjg59@cavan.codon.org.uk X-SA-Exim-Scanned: No (on cavan.codon.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Nov 10, 2009 at 02:12:41PM +0800, Luming Yu wrote: > I came across acpi processor idle driver, noticed that we can cut a > bit overhead at C3 entry that can improve C3 residency a bit, > especially when it has similar kernel config as old RHEL 5 kernel > (2.6.18) on systems with as many as 64 logical CPUs. The point of this > patch is bm_sts is an optional bit. It never returns 1 on systems with > bm_check && !bm_control I tested. Instead, I have observed lower C3 > residency due to accessing bm_sts and relevant code on a system with > 64 logical CPUs with HZ=1000. Please review. If make sense, please > apply. Saves 40W or so on a dual-socket Nehalem system here. Is there a reason it wasn't picked up? -- Matthew Garrett | mjg59@srcf.ucam.org