From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756214Ab2CEBfW (ORCPT ); Sun, 4 Mar 2012 20:35:22 -0500 Received: from mga01.intel.com ([192.55.52.88]:34211 "EHLO mga01.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754925Ab2CEBfV (ORCPT ); Sun, 4 Mar 2012 20:35:21 -0500 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.71,315,1320652800"; d="scan'208";a="133351759" Subject: Re: Subject: [PATCH] cpuidle: Add a sysfs entry to disable specific C state for debug purpose. From: Yanmin Zhang Reply-To: yanmin_zhang@linux.intel.com To: Andrew Morton Cc: "linux-kernel@vger.kernel.org" , "Brown, Len" , "Liu, ShuoX" , Ingo Molnar , Thomas Gleixner , "H. Peter Anvin" In-Reply-To: <20120302142303.648285a7.akpm@linux-foundation.org> References: <1330647453.1916.7.camel@ymzhang> <20120302142303.648285a7.akpm@linux-foundation.org> Content-Type: text/plain; charset="UTF-8" Organization: UMG Date: Mon, 05 Mar 2012 09:34:31 +0800 Message-ID: <1330911271.1916.14.camel@ymzhang> Mime-Version: 1.0 X-Mailer: Evolution 2.30.3 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 2012-03-02 at 14:23 -0800, Andrew Morton wrote: > On Fri, 02 Mar 2012 08:17:33 +0800 > Yanmin Zhang wrote: > > > On Wed, 2012-02-29 at 04:55 +0000, Liu, ShuoX wrote: > > > From: ShuoX Liu > > > > > > Some C states of new CPU might be not good. One reason is BIOS might configure > > > them incorrectly. To help developers root cause it quickly, the patch adds a > > > new sysfs entry, so developers could disable specific C state manually. > > > > > > In addition, C state might have much impact on performance tuning, as it takes > > > much time to enter/exit C states, which might delay interrupt processing. With > > > the new debug option, developers could check if a deep C state could impact > > > performance and how much impact it could cause. > > > > > > Signed-off-by: ShuoX Liu > > Andrew, > > > > Would you like to merge the patch into your testing tree? > > I can do that, but it's hardly my area and I can't comment on the > desirability of the patch and Len is having quiet time. Perhaps the > x86 guys can take a look please> > > > It's useful to help developers debug some issues. > > It would help developers more if it was documented a bit. As it > stands, they'd be lucky if they even knew it existed. > > Looky: > > akpm:/usr/src/linux-3.3-rc5> grep -ril cpuidle Documentation > Documentation/trace/events-power.txt > Documentation/ABI/testing/sysfs-devices-system-cpu > Documentation/kernel-parameters.txt > Documentation/00-INDEX > Documentation/cpuidle/core.txt > Documentation/cpuidle/sysfs.txt > Documentation/cpuidle/driver.txt > Documentation/cpuidle/governor.txt Thanks Andrew. We checked above document files. The best place to record the new entry is Documentation/cpuidle/sysfs.txt. We would change it and resend the patch.