From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 663B1221DB3; Thu, 22 May 2025 08:43:06 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.140.110.172 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1747903389; cv=none; b=Qhsa8fpMiiOAcpWv5FbG+IQEJwt3P/i6r6M806snf6+FBM8tOQ8oZUIu3ESUJh5mlj8P7/yGebG1IK+MwHBTIheAtH3Rfw8yP4ldONIuERuYyJ2Ugoz2Ey2odLnW2fl41H38gg1Kvju0so/VfMK1BGMnFnUwsHau8ALaA/N2g3E= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1747903389; c=relaxed/simple; bh=MLgJr4DqWEmGJovEN1mYiASzZcP9xU2E8Kh3tstQ6V8=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=SGpRecZPB9cFipvafVFggC1XXAypn21CvF4jj5hXxUVsZmZ6CVccgZGLtw1PE4Qtd8jYkMKw7EpZ5AdVlrHUPhbsPY5F7NUbkm3B5t4RmNyuUGpTrQkreLyb9y+//tzYJOFqSvtVR/pdCbHkVgPcDsYU3UnFugIS/piQaOIz/zA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com; spf=pass smtp.mailfrom=arm.com; arc=none smtp.client-ip=217.140.110.172 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=arm.com 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 8CC0A1D13; Thu, 22 May 2025 01:42:51 -0700 (PDT) Received: from [10.57.46.113] (unknown [10.57.46.113]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 9D9443F5A1; Thu, 22 May 2025 01:43:03 -0700 (PDT) Message-ID: <040a0850-a686-42c3-832c-07494cac8ef0@arm.com> Date: Thu, 22 May 2025 09:43:08 +0100 Precedence: bulk X-Mailing-List: linux-pm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2] PM: EM: Add inotify support when the energy model is updated. To: Changwoo Min Cc: christian.loehle@arm.com, tj@kernel.org, pavel@kernel.org, kernel-dev@igalia.com, linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org, len.brown@intel.com, "Rafael J. Wysocki" References: <20250507014728.6094-1-changwoo@igalia.com> <90834b07-9261-4be6-a10b-88d3f5308e1e@igalia.com> <96b4ae67-b9a8-47d3-a951-a880848e6719@arm.com> Content-Language: en-US From: Lukasz Luba In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit On 5/22/25 09:35, Changwoo Min wrote: > > > On 5/22/25 17:19, Lukasz Luba wrote: >> >> >> On 5/10/25 12:34, Rafael J. Wysocki wrote: >>> On Sat, May 10, 2025 at 7:07 AM Changwoo Min >>> wrote: > >>>> I am curious about whether the energy mode is likely to be updated more >>>> often with this change. How often the energy model is likely to be >>>> updated is the factor to be considered for the interface and the model >>>> to post-processing the eneergy model (in the BPF schedulers). >>> >>> It really is hard to say precisely because eventually this will depend >>> on the platform firmware.  Hopefully, this is not going to happen too >>> often, but if the thermal envelope of the platform is tight, for >>> instance, it may not be the case. >> >> It's hard to say for all use cases, but there are some easy to measure >> and understand: >> >> 1. Long scenarios with heavy GPU usage (e.g. gaming). Power on CPUs >>     built from High-Performance cells can be affected by +20% and after >>     ~1min >> 2. Longer recording with heavy ISP usage, similar to above >> >> In those two, it's sufficient to update the EM every 1-3sec to reach >> this +20% after 60sec. Although, at the beginning when the GPU starts >> heating the updates should happen a bit more often. >> >> There are some more complex cases, e.g. when more than 1 Big CPU does >> heavy computations and the heat is higher than normal EM model of >> single CPU (even for that scenario profile). Then the updates to EM >> can go a bit more often (it depends what the platform would like >> to leverage and achieve w/ SW). > > Thank you for the further clarification. I think the netlink > notification should be fast and efficient enough to cover these scenarios. Yes, I agree