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 8CC6FC433EF for ; Wed, 27 Apr 2022 09:21:43 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231371AbiD0JYv (ORCPT ); Wed, 27 Apr 2022 05:24:51 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:33592 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229757AbiD0JYt (ORCPT ); Wed, 27 Apr 2022 05:24:49 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 5A1AD28F963 for ; Wed, 27 Apr 2022 02:20:51 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 2E08E61CEC for ; Wed, 27 Apr 2022 09:20:36 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 664F2C385AA; Wed, 27 Apr 2022 09:20:34 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1651051235; bh=m9uxew7Ob+mN18WzmXF2f6e5Z5voUIFfMjJGwq2tpr0=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=ecnrmmJjKkvpYal7Ghn5bftg1xtu7Z0Gme56Wvq6DjVirZBbOhPRm0lt2jBIuv9xu 0ONfHQ/Gey4P+DI8K4cAR/b0dWSQKRuIta1DfsqsJBRVGHVJprNh2XD7r7x5M0uU+E 3kEoSbKrCNRTIi3v5SyHv5br8RfVjDoi81AzfJu4= Date: Wed, 27 Apr 2022 11:20:31 +0200 From: Greg KH To: Lukasz Luba 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 Subject: Re: [PATCH v4] arch_topology: Trace the update thermal pressure Message-ID: 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). > > Signed-off-by: Lukasz Luba Much better, thanks. I'll wait for Sudeep's comments/review before taking it into my tree. greg k-h