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 5BDC6C433EF for ; Thu, 5 May 2022 09:17:08 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1352198AbiEEJUp (ORCPT ); Thu, 5 May 2022 05:20:45 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60074 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235961AbiEEJUj (ORCPT ); Thu, 5 May 2022 05:20:39 -0400 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 930EF2E9ED for ; Thu, 5 May 2022 02:17:00 -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 0786E1042; Thu, 5 May 2022 02:17:00 -0700 (PDT) Received: from bogus (e103737-lin.cambridge.arm.com [10.1.197.49]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id BA38F3FA27; Thu, 5 May 2022 02:16:58 -0700 (PDT) Date: Thu, 5 May 2022 10:16:56 +0100 From: Sudeep Holla To: Lukasz Luba Cc: linux-kernel@vger.kernel.org, dietmar.eggemann@arm.com, vincent.guittot@linaro.org, gregkh@linuxfoundation.org, rafael@kernel.org, rostedt@goodmis.org, mingo@redhat.com, Sudeep Holla Subject: Re: [PATCH v4] arch_topology: Trace the update thermal pressure Message-ID: <20220505091656.2ryeyy5c7wy73uqh@bogus> References: <20220427080806.1906-1-lukasz.luba@arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220427080806.1906-1-lukasz.luba@arm.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Apr 27, 2022 at 09:08:06AM +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). > Sorry for missing this, looks good to me. Acked-by: Sudeep Holla -- Regards, Sudeep