From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757020Ab3BFCFZ (ORCPT ); Tue, 5 Feb 2013 21:05:25 -0500 Received: from relay1.sgi.com ([192.48.179.29]:35802 "EHLO relay.sgi.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754258Ab3BFCFX (ORCPT ); Tue, 5 Feb 2013 21:05:23 -0500 From: Nathan Zimmer To: viresh.kumar@linaro.org, rjw@sisk.pl Cc: linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org, cpufreq@vger.kernel.org, Nathan Zimmer Subject: [PATCH v2 linux-next 0/2] cpufreq: cpufreq_driver_lock is hot on large systems Date: Tue, 5 Feb 2013 20:04:48 -0600 Message-Id: <1360116290-23849-1-git-send-email-nzimmer@sgi.com> X-Mailer: git-send-email 1.8.0.1 In-Reply-To: <74F10842A85F514CA8D8C487E74474BB2D2F925E@P-EXMB1-DC21.corp.sgi.com> References: <74F10842A85F514CA8D8C487E74474BB2D2F925E@P-EXMB1-DC21.corp.sgi.com> 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 significant 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. v2: Rebase to linux-next 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 | 150 +++++++++++++++++++++++++--------------------- 1 file changed, 83 insertions(+), 67 deletions(-) -- 1.8.0.1