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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 5144EC433F5 for ; Wed, 27 Apr 2022 08:02:08 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1359255AbiD0IFQ (ORCPT ); Wed, 27 Apr 2022 04:05:16 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34080 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S243567AbiD0IFM (ORCPT ); Wed, 27 Apr 2022 04:05:12 -0400 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id B8507152485 for ; Wed, 27 Apr 2022 01:02:01 -0700 (PDT) Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 82D52ED1; Wed, 27 Apr 2022 01:02:01 -0700 (PDT) Received: from [10.57.7.196] (unknown [10.57.7.196]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id D1F6E3F5A1; Wed, 27 Apr 2022 01:01:59 -0700 (PDT) Message-ID: Date: Wed, 27 Apr 2022 09:01:58 +0100 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.7.0 Subject: Re: [PATCH v3] arch_topology: Trace the update thermal pressure Content-Language: en-US To: Greg KH Cc: linux-kernel@vger.kernel.org, sudeep.holla@arm.com, dietmar.eggemann@arm.com, vincent.guittot@linaro.org, rafael@kernel.org, rostedt@goodmis.org, mingo@redhat.com References: <20220427073551.19032-1-lukasz.luba@arm.com> <38c8a684-5fcc-cfb3-424c-d353a7bafe03@arm.com> From: Lukasz Luba In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 4/27/22 08:58, Greg KH wrote: > On Wed, Apr 27, 2022 at 08:52:50AM +0100, Lukasz Luba wrote: >> >> >> On 4/27/22 08:44, Greg KH wrote: >>> On Wed, Apr 27, 2022 at 08:35:51AM +0100, Lukasz Luba wrote: >>>> Add trace event to capture the moment of the call for updating the thermal >>>> pressure value. It's helpful to investigate how often those events occur >>>> in a system dealing with throttling. This trace event is needed since the >>>> old 'cdev_update' might not be used by some drivers. >>>> >>>> The old 'cdev_update' trace event only provides a cooling state >>>> value: [0, n]. That state value then needs additional tools to translate >>>> it: state -> freq -> capacity -> thermal pressure. This new trace event >>>> just stores proper thermal pressure value in the trace buffer, no need >>>> for additional logic. This is helpful for cooperation when someone can >>>> simply sends to the list the trace buffer output from the platform (no >>>> need from additional information from other subsystems). >>>> >>>> There are also platforms which due to some design reasons don't use >>>> cooling devices and thus don't trigger old 'cdev_update' trace event. >>>> They are also important and measuring latency for the thermal signal >>>> raising/decaying characteristics is in scope. This new trace event >>>> would cover them as well. >>>> >>>> We already have a trace point 'pelt_thermal_tp' which after a change to >>>> trace event can be paired with this new 'thermal_pressure_update' and >>>> derive more insight what is going on in the system under thermal pressure >>>> (and why). >>>> >>>> Reported-by: kernel test robot >>> >>> The kernel test robot did not report that you needed to add a new trace >>> event :( >>> >> >> I got feedback from the test robot for v1, which figured out that >> the riscv configuration is broken. You can find it here >> https://lore.kernel.org/lkml/202204201654.vcszVDGb-lkp@intel.com/ >> >> So, I've added that tag following: >> "If you fix the issue, kindly add following tag as appropriate" >> >> Should this only be honored when a patch actually got into next >> and then following patch with a fix would have that tag? > > Yes. And you can mention it in the version information about what > changed between each patch version below the --- line, but as is, you > can see how this does not make sense. > Thank you Greg for the explanation. I'll remove the tag in v4. Regards, Lukasz