From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 52028C433EF for ; Tue, 19 Jun 2018 12:41:08 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id EEEF620836 for ; Tue, 19 Jun 2018 12:41:07 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org EEEF620836 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S937833AbeFSMlG (ORCPT ); Tue, 19 Jun 2018 08:41:06 -0400 Received: from usa-sjc-mx-foss1.foss.arm.com ([217.140.101.70]:49000 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S937705AbeFSMlF (ORCPT ); Tue, 19 Jun 2018 08:41:05 -0400 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.72.51.249]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id D493B1435; Tue, 19 Jun 2018 05:41:04 -0700 (PDT) Received: from e108498-lin.cambridge.arm.com (e108498-lin.cambridge.arm.com [10.1.211.46]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id DFCB23F557; Tue, 19 Jun 2018 05:41:00 -0700 (PDT) Date: Tue, 19 Jun 2018 13:40:59 +0100 From: Quentin Perret To: Peter Zijlstra Cc: rjw@rjwysocki.net, gregkh@linuxfoundation.org, linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org, mingo@redhat.com, dietmar.eggemann@arm.com, morten.rasmussen@arm.com, chris.redpath@arm.com, patrick.bellasi@arm.com, valentin.schneider@arm.com, vincent.guittot@linaro.org, thara.gopinath@linaro.org, viresh.kumar@linaro.org, tkjos@google.com, joelaf@google.com, smuckle@google.com, adharmap@quicinc.com, skannan@quicinc.com, pkondeti@codeaurora.org, juri.lelli@redhat.com, edubezval@gmail.com, srinivas.pandruvada@linux.intel.com, currojerez@riseup.net, javi.merino@kernel.org Subject: Re: [RFC PATCH v3 03/10] PM: Introduce an Energy Model management framework Message-ID: <20180619124058.GX17720@e108498-lin.cambridge.arm.com> References: <20180521142505.6522-1-quentin.perret@arm.com> <20180521142505.6522-4-quentin.perret@arm.com> <20180619113106.GP2458@hirez.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180619113106.GP2458@hirez.programming.kicks-ass.net> User-Agent: Mutt/1.8.3 (2017-05-23) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tuesday 19 Jun 2018 at 13:31:06 (+0200), Peter Zijlstra wrote: > On Mon, May 21, 2018 at 03:24:58PM +0100, Quentin Perret wrote: > > + read_lock_irqsave(&em_data_lock, flags); > > + for_each_cpu(cpu, cpu_possible_mask) { > > I know we're likely to only use this on small systems, but this pattern > is a very bad, Please look at alternatives. Ok, this isn't supposed to be called very often (only once, at boot time, for Arm for example), but I see your point.