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 lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 47039C36002 for ; Mon, 24 Mar 2025 16:38:27 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1twkoL-0004ab-P6; Mon, 24 Mar 2025 12:38:01 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1twkoJ-0004aL-B5 for qemu-devel@nongnu.org; Mon, 24 Mar 2025 12:37:59 -0400 Received: from gw2-out.univ-tlse3.fr ([195.220.43.154]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1twkoG-0008Pf-GM for qemu-devel@nongnu.org; Mon, 24 Mar 2025 12:37:59 -0400 DKIM-Filter: OpenDKIM Filter v2.10.3 prod-zextras-mta-out02.univ-tlse3.fr 9F25A18043B DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=univ-tlse3.fr; s=c439b0a7-3b73-4fd0-9251-89a2c958e908; t=1742834268; bh=R4kvN5qczl48uagi1mURVMUSoXMvNrXjxCY5Yardw04=; h=Date:From:To:Message-ID:MIME-Version; b=k1PvA1GCE3OGpe4xB9IbA8cKJrpBsY1SYKkcb0JTP5Y0kaclrXwO/AyXcAg3/tahO vCnEjpZposZFqKRNcODgl4lnGLcjE1O7u3dIQFUiTU0PJX8tX6AqXnxuUEJwNxwIqZ U/Z1qZDzWtpdbi70dqo6jkwShfFIF5Xc1ViufedXqiQG49OSWKo/6O4WD+vciZqkvM n2fs1wfqwtDKKWI5qi2q1eOceCiRWCa4jYno5mgBJ1aJouCg406PrRUbfPXeILLrs4 xAgDGfSkQIP2N9hHpU2Es4uHfRhQYGnM6U+v4v4d52hpJNk9Abem1Rk5QIEO0hUvYH Y1lsGyTRVJwng== Date: Mon, 24 Mar 2025 17:37:48 +0100 (CET) From: clement.aldebert@univ-tlse3.fr To: Peter Maydell Cc: laurent polzin , "millian.poquet" , qemu-devel , Alex =?utf-8?Q?Benn=C3=A9e?= Message-ID: <975738318.22990772.1742834268217.JavaMail.zimbra@univ-tlse3.fr> In-Reply-To: References: <87ecytm2ru.fsf@draig.linaro.org> <4545005.21021813.1742490863752.JavaMail.zimbra@univ-tlse3.fr> Subject: Re: Raspberry Pi 3B energy consumption MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable X-Mailer: Zimbra 9.0.0_ZEXTRAS_9043 (ZimbraWebClient - GC134 (Win)/9.0.0_ZEXTRAS_9043) Thread-Topic: Raspberry Pi 3B energy consumption Thread-Index: 2B2R7v52zFgHfxmwHzbb6pF5oa658g== Received-SPF: pass client-ip=195.220.43.154; envelope-from=clement.aldebert@univ-tlse3.fr; helo=gw2-out.univ-tlse3.fr X-Spam_score_int: -43 X-Spam_score: -4.4 X-Spam_bar: ---- X-Spam_report: (-4.4 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_MED=-2.3, RCVD_IN_VALIDITY_CERTIFIED_BLOCKED=0.001, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Dear Peter Maydell, Thank you for your detailed response. We will take a closer look at why, when using WFI, the affected cores still= appear to be at 100% utilization in htop. Additionally, we will investigat= e whether implementing WFE in QEMU would be necessary to achieve proper CPU= core shutdown. Currently, we are not using PSCI, but this does seem like a promising appro= ach that we will explore further. Regarding the use of the "virt" machine, our supervisor, M. Poquet, require= s the Raspberry Pi 3B specifically for his courses due to its hardware spec= ifications. Therefore, switching to "virt" would only be considered as a la= st resort. Thank you again for your insights. Any further recommendations would be gre= atly appreciated. Best regards, Cl=C3=A9ment Aldebert & Laurent Polzin ----- Mail original ----- De: "Peter Maydell" =C3=80: "clement aldebert" Cc: "Alex Benn=C3=A9e" , "qemu-devel" , "millian.poquet" , "laurent polzi= n" Envoy=C3=A9: Jeudi 20 Mars 2025 21:11:52 Objet: Re: Raspberry Pi 3B energy consumption On Thu, 20 Mar 2025 at 20:09, Peter Maydell wrot= e: > If you need WFE to work, that's certainly feasible and something it would > be nice to see, but potentially quite a bit of work in the guts of QEMU's > arm emulation. (Basically going to sleep on WFE is easy but then making > sure that all the events and situations that need to wake up a WFE is > tedious. We implement sleep-on-WFI but not sleep-on-WFI because the set should read "sleep-on-WFI but not sleep-on-WFE", of course. Oops... > of WFI-wakeup events is rather smaller than the WFE-wakeup events.) It's > been in the "we really should implement this but since the only downside > is the host CPUs spinning, we've never got round to it" bucket for years. -- PMM