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=-4.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,HK_RANDOM_FROM,MAILING_LIST_MULTI,NICE_REPLY_A, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,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 713CCC433ED for ; Thu, 1 Apr 2021 11:38:24 +0000 (UTC) Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 1D99A60BD3 for ; Thu, 1 Apr 2021 11:38:24 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 1D99A60BD3 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linux.intel.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=dri-devel-bounces@lists.freedesktop.org Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 7FC276EC90; Thu, 1 Apr 2021 11:38:21 +0000 (UTC) Received: from mga05.intel.com (mga05.intel.com [192.55.52.43]) by gabe.freedesktop.org (Postfix) with ESMTPS id A7F226E175; Thu, 1 Apr 2021 11:38:19 +0000 (UTC) IronPort-SDR: dgpZbv4/eabFt+TEiC+tH/Qp0+M42DBnTHyRcCdxcHkajTgLE5TrGLvKjiGVoi48vpRrpYLrfi g1YcViBLl4jQ== X-IronPort-AV: E=McAfee;i="6000,8403,9940"; a="277412152" X-IronPort-AV: E=Sophos;i="5.81,296,1610438400"; d="scan'208";a="277412152" Received: from orsmga001.jf.intel.com ([10.7.209.18]) by fmsmga105.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 01 Apr 2021 04:38:19 -0700 IronPort-SDR: cXAAwLBPety1yVNKU0RUlCjQl8np80M95+7XNmPmC4da4bm8MkM+tuUTcXLnpVJ2rlrnUCtnO0 kMtwtXvruMWg== X-IronPort-AV: E=Sophos;i="5.81,296,1610438400"; d="scan'208";a="455949863" Received: from shaneken-mobl.ger.corp.intel.com (HELO [10.213.202.146]) ([10.213.202.146]) by orsmga001-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 01 Apr 2021 04:38:17 -0700 Subject: Re: [Intel-gfx] [PATCH] drm/i915/pmu: Check actual RC6 status To: "Tamminen, Eero T" , "Vivi, Rodrigo" References: <20210331101850.2582027-1-tvrtko.ursulin@linux.intel.com> <2c813fb2-6836-1888-f606-25ef1321a366@linux.intel.com> From: Tvrtko Ursulin Organization: Intel Corporation UK Plc Message-ID: <09ef3e30-4ca0-144f-af0a-358691f2fedb@linux.intel.com> Date: Thu, 1 Apr 2021 12:38:15 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.7.1 MIME-Version: 1.0 In-Reply-To: Content-Language: en-US X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: "Intel-gfx@lists.freedesktop.org" , "dri-devel@lists.freedesktop.org" Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" On 01/04/2021 11:24, Tamminen, Eero T wrote: > Hi, > > On Thu, 2021-04-01 at 05:54 -0400, Rodrigo Vivi wrote: >> On Thu, Apr 01, 2021 at 10:38:11AM +0100, Tvrtko Ursulin wrote: > ... >>> I think it is possible to argue both ways. >>> >>> 1) >>> HAS_RC6 means hardware has RC6 so if we view PMU as very low level >>> we can >>> say always export it. >>> >>> If i915 had to turn it off (rc6->supported == false) due firmware or >>> GVT-g, >>> then we could say reporting zero RC6 is accurate in that sense. Only >>> the >>> reason "why it is zero" is missing for PMU users. >>> >>> 2) >>> Or if we go with this patch we could say that presence of the PMU >>> metric >>> means RC6 is active and enabled, while absence means it is either >>> not >>> supported due platform (or firmware) or how the platform is getting >>> used >>> (GVT-g). >>> >> >> yeap, these 2 cases described well my mental conflict... >> >>> So I think patch is a bit better. I don't see it is adding more >>> confusion. >> >> As I said on the other patch I have no strong position on which is >> better, >> but if you and Eero feel that this works better for the current case, >> let's do it... > > IMHO seeing case 1) i.e. zero RC6 could be slightly better from user > point of view than not seeing RC6 at all, because: > > A) user then knows that GPU is not entering RC6, and > > B) then the question is why it's not going to RC6 => one can see from > sysfs that it has been disabled > > > Whereas in case 2), the question is why there's no RC6 info, and user > doesn't know whether GPU is suspended or not (i.e. why GPU power > consumption is higher than expected). It would help if i-g-t could show > e.g. "RC6 OFF" in that case. So many options.. :) It can be handle on the "presentation" layer (intel_gpu_top). If we go with this patch but different errnos it could indeed distinguish and either not show RC6 or say "RC6 OFF". If we go with the other patch (https://patchwork.freedesktop.org/patch/426589/?series=88580&rev=1) then intel_gpu_top could really still do the same by looking at /sys/class/drm/card0/power/rc6_enable. So strictly no i915 patch is even needed to provide clarity in intel_gpu_top. But still one of those two i915 patches is required to improve how low-level Perf/PMU RC6 counter gets exposed (or not exposed). I don't have a strong preference which one to take either. :) Regards, Tvrtko _______________________________________________ dri-devel mailing list dri-devel@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/dri-devel