From patchwork Fri Mar 18 04:11:48 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Michael Neuling X-Patchwork-Id: 8616051 Return-Path: X-Original-To: patchwork-linux-pm@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork2.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.136]) by patchwork2.web.kernel.org (Postfix) with ESMTP id 1B1CAC0553 for ; Fri, 18 Mar 2016 04:11:55 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 4D60F2037F for ; Fri, 18 Mar 2016 04:11:54 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 453C120382 for ; Fri, 18 Mar 2016 04:11:53 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751444AbcCRELu (ORCPT ); Fri, 18 Mar 2016 00:11:50 -0400 Received: from ozlabs.org ([103.22.144.67]:55522 "EHLO ozlabs.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751442AbcCRELu convert rfc822-to-8bit (ORCPT ); Fri, 18 Mar 2016 00:11:50 -0400 Received: from localhost.localdomain (localhost [127.0.0.1]) by ozlabs.org (Postfix) with ESMTP id 3qRBch5BtJz9sBM; Fri, 18 Mar 2016 15:11:48 +1100 (AEDT) Received: by localhost.localdomain (Postfix, from userid 1000) id AE157EEB216; Fri, 18 Mar 2016 15:11:48 +1100 (AEDT) Message-ID: <1458274308.6622.79.camel@neuling.org> Subject: Re: [PATCH v8 3/6] cpufreq: powernv: Remove cpu_to_chip_id() from hot-path From: Michael Neuling To: Shilpasri G Bhat , linuxppc-dev@ozlabs.org, linux-kernel@vger.kernel.org Cc: ego@linux.vnet.ibm.com, linux-pm@vger.kernel.org, viresh.kumar@linaro.org, rjw@rjwysocki.net, pc@us.ibm.com, shreyas@linux.vnet.ibm.com, anton@samba.org Date: Fri, 18 Mar 2016 15:11:48 +1100 In-Reply-To: <1458273857.6622.75.camel@neuling.org> References: <1454442102-1229-1-git-send-email-shilpa.bhat@linux.vnet.ibm.com> <1454442102-1229-4-git-send-email-shilpa.bhat@linux.vnet.ibm.com> <1458273857.6622.75.camel@neuling.org> X-Mailer: Evolution 3.16.5-1ubuntu3.1 Mime-Version: 1.0 Sender: linux-pm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-pm@vger.kernel.org X-Spam-Status: No, score=-6.9 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_HI, RP_MATCHES_RCVD, UNPARSEABLE_RELAY autolearn=unavailable version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP On Fri, 2016-03-18 at 15:04 +1100, Michael Neuling wrote: > On Wed, 2016-02-03 at 01:11 +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 > > Acked-by: Viresh Kumar > > --- > > No changes from v7. > > How about this instead? It removes the linear lookup and seems a lot > less complex. BTW we never init nr_chips before using it. We also need something like. --- To unsubscribe from this list: send the line "unsubscribe linux-pm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html diff --git a/drivers/cpufreq/powernv-cpufreq.c b/drivers/cpufreq/powernv-cpufreq.c index d63d2cb..c819ed4 100644 --- a/drivers/cpufreq/powernv-cpufreq.c +++ b/drivers/cpufreq/powernv-cpufreq.c @@ -556,6 +556,8 @@ static int init_chip_info(void) unsigned int cpu, i; unsigned int prev_chip_id = UINT_MAX; + nr_chips = 0; + for_each_possible_cpu(cpu) { unsigned int id = cpu_to_chip_id(cpu);