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 152FDEB64DA for ; Wed, 28 Jun 2023 17:27:43 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1qEYwU-0001c2-Ar; Wed, 28 Jun 2023 13:26:58 -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 1qEYwS-0001bo-VF for qemu-devel@nongnu.org; Wed, 28 Jun 2023 13:26:56 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1qEYwR-0004sv-Gw for qemu-devel@nongnu.org; Wed, 28 Jun 2023 13:26:56 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1687973214; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=6CKHaLdD6MUf5lvnyDsPv4nM3yOoVncz5ZyEqeb2Kto=; b=ZkEVa2nAhaHrZSCNthy+APxt0wduZ6LXoWbVQaZ0mPvwwqRkmuUd5uJMzkRjfYOb9MA+O0 Hm5oo2JqdxlYJYdK2JUNYWOj53hQ6ybQuQPj4NVcPJJRutcp/XPq84QSNwEUihMr4k6rQd /HnuHOu94yvY+CGJF72sKFVUZmxv0R8= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-158-5mLvSTM1PoaPaW_3_E8o2g-1; Wed, 28 Jun 2023 13:26:52 -0400 X-MC-Unique: 5mLvSTM1PoaPaW_3_E8o2g-1 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.rdu2.redhat.com [10.11.54.6]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id A8FA1104458D for ; Wed, 28 Jun 2023 17:26:52 +0000 (UTC) Received: from tpad.localdomain (ovpn-112-2.gru2.redhat.com [10.97.112.2]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 67A922166B25; Wed, 28 Jun 2023 17:26:52 +0000 (UTC) Received: by tpad.localdomain (Postfix, from userid 1000) id 3D345403C37D3; Wed, 28 Jun 2023 14:26:36 -0300 (-03) Date: Wed, 28 Jun 2023 14:26:36 -0300 From: Marcelo Tosatti To: Anthony Harivel Cc: pbonzini@redhat.com, qemu-devel@nongnu.org Subject: Re: [PATCH] Add support for RAPL MSRs in KVM/Qemu Message-ID: References: <20230616140830.316655-1-aharivel@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20230616140830.316655-1-aharivel@redhat.com> X-Scanned-By: MIMEDefang 3.1 on 10.11.54.6 Received-SPF: pass client-ip=170.10.133.124; envelope-from=mtosatti@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H5=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 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 On Fri, Jun 16, 2023 at 04:08:30PM +0200, Anthony Harivel wrote: > Starting with the "Sandy Bridge" generation, Intel CPUs provide a RAPL > interface (Running Average Power Limit) for advertising the accumulated > energy consumption of various power domains (e.g. CPU packages, DRAM, > etc.). > > The consumption is reported via MSRs (model specific registers) like > MSR_PKG_ENERGY_STATUS for the CPU package power domain. These MSRs are > 64 bits registers that represent the accumulated energy consumption in > micro Joules. They are updated by microcode every ~1ms. > > For now, KVM always returns 0 when the guest requests the value of > these MSRs. Use the KVM MSR filtering mechanism to allow QEMU handle > these MSRs dynamically in userspace. > > To limit the amount of system calls for every MSR call, create a new > thread in QEMU that updates the "virtual" MSR values asynchronously. > > Each vCPU has its own vMSR to reflect the independence of vCPUs. The > thread updates the vMSR values with the ratio of energy consumed of > the whole physical CPU package the vCPU thread runs on and the > thread's utime and stime values. > > All other non-vCPU threads are also taken into account. Their energy > consumption is evenly distributed among all vCPUs threads running on > the same physical CPU package. > > This feature is activated with -accel kvm,rapl=true. I suppose this should be a CPU flag instead? -cpu xxx,rapl=on.