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=-2.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no 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 4114EC433DF for ; Mon, 8 Jun 2020 06:52:30 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 217BB206A4 for ; Mon, 8 Jun 2020 06:52:30 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728334AbgFHGw2 (ORCPT ); Mon, 8 Jun 2020 02:52:28 -0400 Received: from mga11.intel.com ([192.55.52.93]:17633 "EHLO mga11.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726929AbgFHGw1 (ORCPT ); Mon, 8 Jun 2020 02:52:27 -0400 IronPort-SDR: cp9X9B84NAjPh0/jJ2V5rrR8AkAdWPa3wTMXeSCL97NiC6dw+IAMSQi5+4sdC0m9R2LxMQF3H0 qpaRkDHn2OFg== X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga003.fm.intel.com ([10.253.24.29]) by fmsmga102.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 07 Jun 2020 23:52:26 -0700 IronPort-SDR: mTuTwaNs94YS1DXYh0D7RJaQ3aJ2l6U9lq8UJ0y4jWjDGsH6lBWYNmBD/nA6kW3Bn5pNrPCUYz SzRyVmF9zuog== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.73,487,1583222400"; d="scan'208";a="313797666" Received: from chenyu-office.sh.intel.com ([10.239.158.173]) by FMSMGA003.fm.intel.com with ESMTP; 07 Jun 2020 23:52:25 -0700 Date: Mon, 8 Jun 2020 14:53:24 +0800 From: Chen Yu To: Michal Miroslaw Cc: "Rafael J . Wysocki" , Len Brown , Greg Kroah-Hartman , linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 2/2][RFC] PM-runtime: add tracepoints to cover all usage_count changes Message-ID: <20200608065324.GA9018@chenyu-office.sh.intel.com> References: <6ce5c2d21758363b7c9a31187eda1787bc4a6160.1591380524.git.yu.c.chen@intel.com> <20200605193311.GB9553@qmqm.qmqm.pl> <20200606071459.GA1298@chenyu-office.sh.intel.com> <20200607045535.GD12913@qmqm.qmqm.pl> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200607045535.GD12913@qmqm.qmqm.pl> User-Agent: Mutt/1.9.4 (2018-02-28) Sender: linux-pm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-pm@vger.kernel.org On Sun, Jun 07, 2020 at 06:55:35AM +0200, Michal Miroslaw wrote: > On Sat, Jun 06, 2020 at 03:14:59PM +0800, Chen Yu wrote: > > Hi, > > On Fri, Jun 05, 2020 at 09:33:11PM +0200, Michal Miroslaw wrote: > > > On Sat, Jun 06, 2020 at 03:05:52AM +0800, Chen Yu wrote: > > > > Commit d229290689ae ("PM-runtime: add tracepoints for usage_count changes") > > > > has added some tracepoints to monitor the change of runtime usage, and > > > > there is something to improve: > > > > 1. There are some places that adjust the usage count have not > > > > been traced yet. For example, pm_runtime_get_noresume() and > > > > pm_runtime_put_noidle() > > > > 2. The change of the usage count will not be tracked if decreased > > > > from 1 to 0. > > > [...] > > > > @@ -1448,16 +1453,17 @@ EXPORT_SYMBOL_GPL(pm_runtime_forbid); > > > > */ > > > > void pm_runtime_allow(struct device *dev) > > > > { > > > > + bool is_zero; > > > > + > > > > spin_lock_irq(&dev->power.lock); > > > > if (dev->power.runtime_auto) > > > > goto out; > > > > > > > > dev->power.runtime_auto = true; > > > > - if (atomic_dec_and_test(&dev->power.usage_count)) > > > > + is_zero = atomic_dec_and_test(&dev->power.usage_count); > > > > + trace_rpm_usage_rcuidle(dev, RPM_AUTO | RPM_ASYNC); > > > > + if (is_zero) > > > > rpm_idle(dev, RPM_AUTO | RPM_ASYNC); > > > > - else > > > > - trace_rpm_usage_rcuidle(dev, RPM_AUTO | RPM_ASYNC); > > > > - > > > [...] > > > > > > IIRC, rpm_idle() has a tracepoint already. > > > > > Yes, this is what I concerned previously. If someone > > want to track the change of usage_count, then he might > > have to enable both trace rpm_usage and rpm_idle so > > as to track the moment when the counter drops from 1 to > > 0. It might be more consistent if we only enable > > trace rpm_usage to track the whole process. > > > > @@ -1523,9 +1529,8 @@ static void update_autosuspend(struct device *dev, int old_delay, int old_use) > > > > /* If it used to be allowed then prevent it. */ > > > > if (!old_use || old_delay >= 0) { > > > > atomic_inc(&dev->power.usage_count); > > > > - rpm_resume(dev, 0); > > > > - } else { > > > > trace_rpm_usage_rcuidle(dev, 0); > > > > + rpm_resume(dev, 0); > > > > } > > > > } > > > [...] > > > > > > This actually changes logic, so it doesn't match the patch description. > > > > > This patch intends to adjust the logic to be consistent with > > the change of usage_counter, that is to say, only after the > > counter has been possibly modified, we record it. In current > > logic above, it tracks the usage count where the latter does > > not change. > > I see now what you intended. I think it would be nice to put the idea > (that all usage changes be shown using rpm_usage even if included in > other trace points) into the commit message. Otherwise, looks ok. > Okay, will do in next version, thanks! Chenyu