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=-2.2 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,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 4FCD8C83001 for ; Thu, 30 Apr 2020 07:53:20 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (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 20DB9214D8 for ; Thu, 30 Apr 2020 07:53:20 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="A1A0eAbW"; dkim=fail reason="signature verification failed" (2048-bit key) header.d=st.com header.i=@st.com header.b="mGYUaPC5" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 20DB9214D8 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=st.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+infradead-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=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:Cc:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:Content-ID:In-Reply-To: References:Message-ID:Date:Subject:To:From:Reply-To:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=Ep0YkTF3jAI82ZQxYM56WN2sPS9b0hB5SoUPac7NFSk=; b=A1A0eAbWzxFQTM dMD3buGD+RtFGLcSCCTkKHllFQ8dQguSE0C/rkqRo9wCCK1f1vIUz4R6TLmWCOmYyVrYDnx3xou1/ FodPPCzDKtqlI/Q9wIGwu/5JsZ+SYoXJSX+Dk7VCPLtn/4ih3qoz1DVMxTQlW/bbveywR+FOcCzBb /2wCNgMWMOwnxx3vMC1hq6CZ6LuwD9M4ZcZCQw3KmIEqmPHJoOTZmLHHtBJtiK9RoMtPu1mRPGJog qB0ENvpoHoMNBDOaCD9YMEL8QoYzIBTp1bHxCojK4hg66pUwWazdlDT6V7CSNWqbuDkDofzWEpKWU fcT/mf9Vhjxcfq1qnNqw==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1jU40R-0007Q2-WB; Thu, 30 Apr 2020 07:53:16 +0000 Received: from mx08-00178001.pphosted.com ([91.207.212.93] helo=mx07-00178001.pphosted.com) by bombadil.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1jU40O-0007Ob-Ms for linux-arm-kernel@lists.infradead.org; Thu, 30 Apr 2020 07:53:14 +0000 Received: from pps.filterd (m0046661.ppops.net [127.0.0.1]) by mx07-00178001.pphosted.com (8.16.0.42/8.16.0.42) with SMTP id 03U7qeNP027781; Thu, 30 Apr 2020 09:52:59 +0200 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=st.com; h=from : to : cc : subject : date : message-id : references : in-reply-to : content-type : content-id : content-transfer-encoding : mime-version; s=STMicroelectronics; bh=nNpjPfXaDpTj1MuVss1sEC1CkwsvuNELkclHvxqRjuk=; b=mGYUaPC5tsszTgiYAXjw65KfK8FzSp/hg/Kb/mUbkmqRGx6QAnvnXh9gsypDbQ2ODf1M bZRxTFR46p8V0vmGwe3FP/W18dQhRxiAKXrdKTpvgiqtKJjgzYKPx620HX0lAiZnOQAh qPi+lZslWd68ItaHxvBCmrsobpZWSfzmCuqq2m//xvaRCfgJmxXcvym7NRpzRhVIUzAg YrtUNz57ffn6FIi5CD3vzCU+08AiqoKzJzT4yzHzeBGszUIxb0fLaMWu7YKB9vUFVWKK b7J7E7rC174mGxqie2A/wE8CPGMjh6uN9nFSYKlxG1dyDlD8X3enjL2SPLGXH0eCbJrS BQ== Received: from beta.dmz-eu.st.com (beta.dmz-eu.st.com [164.129.1.35]) by mx07-00178001.pphosted.com with ESMTP id 30mhjx2sv8-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Thu, 30 Apr 2020 09:52:59 +0200 Received: from euls16034.sgp.st.com (euls16034.sgp.st.com [10.75.44.20]) by beta.dmz-eu.st.com (STMicroelectronics) with ESMTP id 5BDA5100034; Thu, 30 Apr 2020 09:52:58 +0200 (CEST) Received: from Webmail-eu.st.com (sfhdag5node3.st.com [10.75.127.15]) by euls16034.sgp.st.com (STMicroelectronics) with ESMTP id 3BE402AAF69; Thu, 30 Apr 2020 09:52:58 +0200 (CEST) Received: from SFHDAG3NODE3.st.com (10.75.127.9) by SFHDAG5NODE3.st.com (10.75.127.15) with Microsoft SMTP Server (TLS) id 15.0.1473.3; Thu, 30 Apr 2020 09:52:57 +0200 Received: from SFHDAG3NODE3.st.com ([fe80::3507:b372:7648:476]) by SFHDAG3NODE3.st.com ([fe80::3507:b372:7648:476%20]) with mapi id 15.00.1347.000; Thu, 30 Apr 2020 09:52:57 +0200 From: Benjamin GAIGNARD To: Valentin Schneider , "Rafael J. Wysocki" Subject: Re: [RFC 0/3] Introduce cpufreq minimum load QoS Thread-Topic: [RFC 0/3] Introduce cpufreq minimum load QoS Thread-Index: AQHWGi06wBgeAQBseECYOK/U7Qvw76iQJdAAgAACCYCAAAQ3AIABBseA Date: Thu, 30 Apr 2020 07:52:57 +0000 Message-ID: <6b5cde14-58b3-045d-9413-223e66b87bf0@st.com> References: <20200424114058.21199-1-benjamin.gaignard@st.com> <7657495.QyJl4BcWH5@kreacher> <30cdecf9-703a-eb2b-7c2b-f1e21c805add@st.com> <70e743cf-b88e-346a-5114-939b8724c83d@arm.com> In-Reply-To: <70e743cf-b88e-346a-5114-939b8724c83d@arm.com> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: user-agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.7.0 x-ms-exchange-messagesentrepresentingtype: 1 x-ms-exchange-transport-fromentityheader: Hosted x-originating-ip: [10.75.127.44] Content-ID: MIME-Version: 1.0 X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.138, 18.0.676 definitions=2020-04-30_02:2020-04-30, 2020-04-30 signatures=0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200430_005313_033681_83DA5C27 X-CRM114-Status: GOOD ( 19.66 ) 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: "mcoquelin.stm32@gmail.com" , Alexandre TORGUE , "len.brown@intel.com" , "viresh.kumar@linaro.org" , "linux-pm@vger.kernel.org" , "linux-kernel@vger.kernel.org" , Patrick Bellasi , "pavel@ucw.cz" , Hugues FRUCHET , "mchehab@kernel.org" , "linux-stm32@st-md-mailman.stormreply.com" , "linux-arm-kernel@lists.infradead.org" , "linux-media@vger.kernel.org" Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 4/29/20 6:12 PM, Valentin Schneider wrote: > On 29/04/2020 16:57, Benjamin GAIGNARD wrote: >> >> On 4/29/20 5:50 PM, Rafael J. Wysocki wrote: >>> On Friday, April 24, 2020 1:40:55 PM CEST Benjamin Gaignard wrote: >>>> When start streaming from the sensor the CPU load could remain very low >>>> because almost all the capture pipeline is done in hardware (i.e. without >>>> using the CPU) and let believe to cpufreq governor that it could use lower >>>> frequencies. If the governor decides to use a too low frequency that >>>> becomes a problem when we need to acknowledge the interrupt during the >>>> blanking time. >>>> The delay to ack the interrupt and perform all the other actions before >>>> the next frame is very short and doesn't allow to the cpufreq governor to >>>> provide the required burst of power. That led to drop the half of the frames. >>>> >>>> To avoid this problem, DCMI driver informs the cpufreq governors by adding >>>> a cpufreq minimum load QoS resquest. >>> This seems to be addressing a use case that can be addressed with the help of >>> utilization clamps with less power overhead. >> Do mean clamping the policy frequencies ? I may have miss the API to do >> that... > IIUC Rafael is referring to uclamp, i.e. scheduler utilization clamping, see: > > https://www.kernel.org/doc/html/latest/admin-guide/cgroup-v2.html#cpu > > The above describes the cgroup interface, note that you can also set clamps > per task (via sched_setattr()). > > One thing that comes to mind however is that schedutil only "sees" the clamps > of runnable tasks, and from reading your changelog you may not have moments > without any (i.e. gears are grinding in HW). You'd have to try boosting > (setting a high uclamp.min) whatever tasks you have on the software side and > see how it all behaves. Relying on userland side means that various applications need to be aware of this specific hardware case and fix it. I was hoping to find a solution in side the kernel to not impact the software side. > >>> Thanks! >>> >>> >>> _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel