From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752462AbcAWI7h (ORCPT ); Sat, 23 Jan 2016 03:59:37 -0500 Received: from mail-pa0-f68.google.com ([209.85.220.68]:33821 "EHLO mail-pa0-f68.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751395AbcAWI7e (ORCPT ); Sat, 23 Jan 2016 03:59:34 -0500 Date: Sat, 23 Jan 2016 19:59:20 +1100 From: Balbir Singh To: Shilpasri G Bhat Cc: linuxppc-dev@ozlabs.org, linux-kernel@vger.kernel.org, rjw@rjwysocki.net, viresh.kumar@linaro.org, linux-pm@vger.kernel.org, pc@us.ibm.com, anton@samba.org, ego@linux.vnet.ibm.com, shreyas@linux.vnet.ibm.com Subject: Re: [PATCH v6 2/5] cpufreq: powernv: Remove cpu_to_chip_id() from hot-path Message-ID: <20160123195920.552990ed@cotter.ozlabs.ibm.com> In-Reply-To: <1453447145-17722-3-git-send-email-shilpa.bhat@linux.vnet.ibm.com> References: <1453447145-17722-1-git-send-email-shilpa.bhat@linux.vnet.ibm.com> <1453447145-17722-3-git-send-email-shilpa.bhat@linux.vnet.ibm.com> X-Mailer: Claws Mail 3.13.1 (GTK+ 2.24.29; x86_64-redhat-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 22 Jan 2016 12:49:02 +0530 Shilpasri G Bhat wrote: > cpu_to_chip_id() does a DT walk through to find out the chip id by > taking a contended device tree lock. This adds an unnecessary overhead > in a hot path. So instead of calling cpu_to_chip_id() everytime cache > the chip ids for all cores in the array 'core_to_chip_map' and use it > in the hotpath. > > Reported-by: Anton Blanchard > Signed-off-by: Shilpasri G Bhat > Reviewed-by: Gautham R. Shenoy snip Does the core_to_chip_map need to be updated/refreshed on/after/ a cpu (core) hotplug? I presume id's don't change Balbir