From patchwork Thu Sep 15 07:31:21 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Mi, Dapeng1" X-Patchwork-Id: 12976959 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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 405D0ECAAA1 for ; Thu, 15 Sep 2022 07:28:51 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229750AbiIOH2t (ORCPT ); Thu, 15 Sep 2022 03:28:49 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53980 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229876AbiIOH1q (ORCPT ); Thu, 15 Sep 2022 03:27:46 -0400 Received: from mga09.intel.com (mga09.intel.com [134.134.136.24]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D3245979D4; Thu, 15 Sep 2022 00:27:16 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1663226836; x=1694762836; h=from:to:cc:subject:date:message-id:mime-version: content-transfer-encoding; bh=46fP1v3/Cp/TNRk09EA9DKMo0jNSNIk8Tld+smpUepY=; b=IWzuPmVNzkxJUwg1wKnoicWmRTOlJezgRZL71ESzf+lCHRTcK4B9OsZ7 mwf6Y4mowwpbqLvneGb3hDACsoM9ZIZz0IWyOPfY1pdezBlhDZHJPj/RM gU5QbySlVzYgjY5u00WsxV4iD0OcrtQo4Lz8YW+gqLJZ5bAg/LORkJvWn 8UlZV3GZDzKTzqkuY7JfTl3uLEeyseSkeWZz66H3PQhka80gOtvNaSO+3 v5iVkfVhmMxBroxd7kOEFrLODwOJyE0ZRB6WJT7D7Xf86GRngVvc9zM9A VC+OKw1oszCqMNSPJqVkDCPegOJgmALB94LKhAboWtyORPjy1LqErC1Vh w==; X-IronPort-AV: E=McAfee;i="6500,9779,10470"; a="299450593" X-IronPort-AV: E=Sophos;i="5.93,317,1654585200"; d="scan'208";a="299450593" Received: from fmsmga004.fm.intel.com ([10.253.24.48]) by orsmga102.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 15 Sep 2022 00:26:45 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.93,317,1654585200"; d="scan'208";a="685614810" Received: from dmi-pnp-i7.sh.intel.com ([10.239.159.145]) by fmsmga004.fm.intel.com with ESMTP; 15 Sep 2022 00:26:43 -0700 From: Dapeng Mi To: seanjc@google.com, pbonzini@redhat.com, tglx@linutronix.de, mingo@redhat.com, dave.hansen@linux.intel.com Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org, zhenyuw@linux.intel.com, Dapeng Mi Subject: [PATCH] KVM: x86: disable halt polling when powersave governor is used Date: Thu, 15 Sep 2022 15:31:21 +0800 Message-Id: <20220915073121.1038840-1-dapeng1.mi@intel.com> X-Mailer: git-send-email 2.34.1 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org Halt polling is enabled by default even through the CPU frequency governor is configured to powersave. Generally halt polling would consume extra power and this's not identical with the intent of powersave governor. disabling halt polling in powersave governor can save the precious power in power critical case. FIO random read test on Alder Lake platform shows halt polling occupies ~17% CPU utilization and consume 7% extra CPU power. After disabling halt polling, CPU has more chance to enter deeper C-states (C1E%: 25.3% -> 33.4%, C10%: 4.4% -> 17.4%). On Alder Lake platform, we don't find there are obvious performance downgrade after disabling halt polling on FIO and Netperf cases. Netperf UDP_RR case runs from two VMs locate on two different physical machines. FIO(MB/s) Base Disable-halt-polling Delta% Rand-read 432.6 436.3 0.8% Netperf Base Disable-halt-polling Delta% UDP_RR 509.8 508.5 -0.3% Signed-off-by: Dapeng Mi --- arch/x86/kvm/x86.c | 17 ++++++++++++++++- 1 file changed, 16 insertions(+), 1 deletion(-) diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index d7374d768296..c0eb6574cbbb 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -13015,7 +13015,22 @@ bool kvm_vector_hashing_enabled(void) bool kvm_arch_no_poll(struct kvm_vcpu *vcpu) { - return (vcpu->arch.msr_kvm_poll_control & 1) == 0; + struct cpufreq_policy *policy = cpufreq_cpu_get(vcpu->cpu); + bool powersave = false; + + /* + * Halt polling could consume much CPU power, if CPU frequency + * governor is set to "powersave", disable halt polling. + */ + if (policy) { + if ((policy->policy == CPUFREQ_POLICY_POWERSAVE) || + (policy->governor && + !strncmp(policy->governor->name, "powersave", + CPUFREQ_NAME_LEN))) + powersave = true; + cpufreq_cpu_put(policy); + } + return ((vcpu->arch.msr_kvm_poll_control & 1) == 0) || powersave; } EXPORT_SYMBOL_GPL(kvm_arch_no_poll);