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=-12.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,NICE_REPLY_A,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=unavailable 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 466DDC41604 for ; Tue, 6 Oct 2020 14:43:45 +0000 (UTC) Received: from merlin.infradead.org (merlin.infradead.org [205.233.59.134]) (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 E698D208FE for ; Tue, 6 Oct 2020 14:43:44 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="MwAJFznU" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org E698D208FE Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=merlin.20170209; h=Sender:Content-Type: Content-Transfer-Encoding:Cc:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:Date:Message-ID:From: References:To:Subject:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=/uWxkdUkjcABhvVqQ8G/9wYEaL4udvFT8kuh798poj0=; b=MwAJFznUYggCmWaSXIGe7vmKh rnwZ/EzEwhQg0mJ//bqX4b8sFBrTMgD0x74wSChtwAi9L+cRIsFV7zbqpxgB0QHjR3U6EFZbotvnW xI9DpJYdSB+qvTCwefDyzictcByr2KE2Lki/3eXAObnC6+F+qCKx+lTpGVd9tzLtNup/PBF3GHKB9 4hpUY8TSd+20RkHikeseNTYZ1oCZUjvFwX2U1H/jAkOn9V6huftrhjEjhGKQORN1CD9RyDZ/1sLUu lIqu9fAZajlIh5ji0IAI0LbvmqCnHZY/v0Xt3a+6bc63cIpxi9/YLv8KH5NEj55dyBtKr9wsal2mk 9OV93kngA==; Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1kPo8P-0007JY-Ex; Tue, 06 Oct 2020 14:40:09 +0000 Received: from foss.arm.com ([217.140.110.172]) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1kPo8L-0007IN-L6; Tue, 06 Oct 2020 14:40:06 +0000 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 01EE8113E; Tue, 6 Oct 2020 07:40:03 -0700 (PDT) Received: from [10.57.54.147] (unknown [10.57.54.147]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id E34B03F71F; Tue, 6 Oct 2020 07:39:59 -0700 (PDT) Subject: Re: [PATCH] thermal: power_allocate: add upper and lower limits To: Michael Kao References: <20200424071601.2636-1-michael.kao@mediatek.com> <1588156776.3573.1.camel@mtksdccf07> <03286571-c110-7f5e-a911-24f8c3e4fd42@arm.com> <1598347775.16267.0.camel@mtksdccf07> From: Lukasz Luba Message-ID: <25cb2d5b-0d87-8a22-a881-a5b6e46307ec@arm.com> Date: Tue, 6 Oct 2020 15:39:57 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.9.0 MIME-Version: 1.0 In-Reply-To: <1598347775.16267.0.camel@mtksdccf07> Content-Language: en-US X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20201006_104005_821872_4B6DBBCC X-CRM114-Status: GOOD ( 31.53 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Mark Rutland , devicetree@vger.kernel.org, srv_heupstream@mediatek.com, linux-pm@vger.kernel.org, Daniel Lezcano , linux-kernel@vger.kernel.org, Eduardo Valentin , Rob Herring , linux-mediatek@lists.infradead.org, hsinyi@chromium.org, Matthias Brugger , Zhang Rui , linux-arm-kernel@lists.infradead.org Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org Hi Michael, On 8/25/20 10:29 AM, Michael Kao wrote: > On Wed, 2020-04-29 at 21:24 +0100, Lukasz Luba wrote: >> >> On 4/29/20 11:39 AM, Michael Kao wrote: >>> On Fri, 2020-04-24 at 10:22 +0100, Lukasz Luba wrote: >>>> Hi Michael, >>>> >>>> On 4/24/20 8:16 AM, Michael Kao wrote: >>>>> The upper and lower limits of thermal throttle state in the >>>>> device tree do not apply to the power_allocate governor. >>>>> Add the upper and lower limits to the power_allocate governor. >>>>> >>>>> Signed-off-by: Michael Kao >>>>> --- >>>>> drivers/thermal/thermal_core.c | 2 +- >>>>> 1 file changed, 1 insertion(+), 1 deletion(-) >>>>> >>>>> diff --git a/drivers/thermal/thermal_core.c b/drivers/thermal/thermal_core.c >>>>> index 9a321dc548c8..f6feed2265bd 100644 >>>>> --- a/drivers/thermal/thermal_core.c >>>>> +++ b/drivers/thermal/thermal_core.c >>>>> @@ -598,7 +598,7 @@ int power_actor_set_power(struct thermal_cooling_device *cdev, >>>>> if (ret) >>>>> return ret; >>>>> >>>>> - instance->target = state; >>>>> + instance->target = clamp_val(state, instance->lower, instance->upper); >>>>> mutex_lock(&cdev->lock); >>>>> cdev->updated = false; >>>>> mutex_unlock(&cdev->lock); >>>>> >>>> >>>> Thank you for the patch and having to look at it. I have some concerns >>>> with this approach. Let's analyze it further. >>>> >>>> In default the cooling devices in the thermal zone which is used by IPA >>>> do not have this 'lower' and 'upper' limits. They are set to >>>> THERMAL_NO_LIMIT in DT to give full control to IPA over the states. >>>> >>>> This the function 'power_actor_set_power' actually translates granted >>>> power to the state that device will run for the next period. >>>> The IPA algorithm has already split the power budget. >>>> Now what happen when the 'lower' value will change the state to a state >>>> which consumes more power than was calculated in the IPA alg... It will >>>> became unstable. >>>> >>>> I would rather see a change which uses these 'lower' and 'upper' limits >>>> before the IPA do the calculation of the power budget. But this wasn't >>>> a requirement and we assumed that IPA has full control over the cooling >>>> device (which I described above with this DT THERMAL_NO_LIMIT). >>>> >>>> Is there a problem with your platform that it has to provide some >>>> minimal performance, so you tried to introduce this clamping? >>>> >>>> Regards, >>>> Lukasz >>> >>> >>> Hi Lukasz, >>> >>> I refer to the documentation settings of the thermal device tree >>> (Documentation / devicetree / bindings / thermal / thermal.txt). >>> >>> It shows that cooling-device is a mandatory property, so max/min cooling >>> state should be able to support in framework point of view. >>> Otherwise, the limitation should be added in binding document. >>> >>> Different hardware mechanisms have different heat dissipation >>> capabilities. >>> Limiting the input heat source can slow down the heat accumulation and >>> temperature burst. >>> We want to reduce the accumulation of heat at high temperature by >>> limiting the minimum gear of thermal throttle. >> >> I agree that these 'lower' and 'upper' limits shouldn't be just >> ignored as is currently. This patch clamps the value at late stage, >> though. >> >> Let me have a look how it could be taken into account in the early >> stage, before the power calculation and split are done. Maybe there >> is a clean way to inject this. >> >> Regards, >> Lukasz > Hi Lukasz, > > After the research, do you have any ideas or suggestions? > > Best Regards, > Michael > My apologies for the delay. I have done some experiments. Could you resend the patch, please make sure it is not encoded in base64 like this one. I am going to take your patch together with some other changes. Regards, Lukasz _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel