From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755619Ab3BEBBD (ORCPT ); Mon, 4 Feb 2013 20:01:03 -0500 Received: from hydra.sisk.pl ([212.160.235.94]:41088 "EHLO hydra.sisk.pl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751215Ab3BEBBB (ORCPT ); Mon, 4 Feb 2013 20:01:01 -0500 From: "Rafael J. Wysocki" To: Nathan Zimmer , Viresh Kumar Cc: linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org, cpufreq@vger.kernel.org, Shawn Guo Subject: Re: [PATCH 0/2] cpufreq: cpufreq_driver_lock is hot on large systems Date: Tue, 05 Feb 2013 02:07:18 +0100 Message-ID: <2765418.Ft0GYkgNgL@vostro.rjw.lan> User-Agent: KMail/4.9.5 (Linux/3.8.0-rc6; KDE/4.9.5; x86_64; ; ) In-Reply-To: <1360017913-25667-1-git-send-email-nzimmer@sgi.com> References: <1360017913-25667-1-git-send-email-nzimmer@sgi.com> MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="utf-8" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Monday, February 04, 2013 04:45:11 PM Nathan Zimmer wrote: > I am noticing the cpufreq_driver_lock is quite hot. > On an idle 512 system perf shows me most of the system time is spent on this > lock. This is quite signifigant as top shows 5% of time in system time. > My solution was to first convert the lock to a rwlock and then to the rcu. > > > Nathan Zimmer (2): > cpufreq: Convert the cpufreq_driver_lock to a rwlock > cpufreq: Convert the cpufreq_driver_lock to use the rcu > > drivers/cpufreq/cpufreq.c | 139 ++++++++++++++++++++++++++-------------------- > 1 file changed, 79 insertions(+), 60 deletions(-) I like these changes. Viresh, anyone, any comments? Rafael -- I speak only for myself. Rafael J. Wysocki, Intel Open Source Technology Center.