From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756005Ab3BDWpy (ORCPT ); Mon, 4 Feb 2013 17:45:54 -0500 Received: from relay3.sgi.com ([192.48.152.1]:45306 "EHLO relay.sgi.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1755938Ab3BDWpw (ORCPT ); Mon, 4 Feb 2013 17:45:52 -0500 From: Nathan Zimmer To: rjw@sisk.pl Cc: linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org, cpufreq@vger.kernel.org, Nathan Zimmer Subject: [PATCH 0/2] cpufreq: cpufreq_driver_lock is hot on large systems Date: Mon, 4 Feb 2013 16:45:11 -0600 Message-Id: <1360017913-25667-1-git-send-email-nzimmer@sgi.com> X-Mailer: git-send-email 1.8.0.1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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(-) -- 1.8.0.1