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=-8.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=ham 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 D8320C433FF for ; Thu, 1 Aug 2019 16:51:15 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B5A7320838 for ; Thu, 1 Aug 2019 16:51:15 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1733189AbfHAQvO (ORCPT ); Thu, 1 Aug 2019 12:51:14 -0400 Received: from mga11.intel.com ([192.55.52.93]:26210 "EHLO mga11.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725804AbfHAQvN (ORCPT ); Thu, 1 Aug 2019 12:51:13 -0400 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga004.jf.intel.com ([10.7.209.38]) by fmsmga102.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 01 Aug 2019 09:51:13 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.64,334,1559545200"; d="scan'208";a="324300981" Received: from rjwysock-mobl1.ger.corp.intel.com (HELO [10.249.145.65]) ([10.249.145.65]) by orsmga004.jf.intel.com with ESMTP; 01 Aug 2019 09:51:11 -0700 Subject: Re: [PATCH] cpuidle-haltpoll: Enable kvm guest polling when dedicated physical CPUs are available To: Wanpeng Li , Paolo Bonzini , Marcelo Tosatti Cc: linux-kernel@vger.kernel.org, kvm@vger.kernel.org, =?UTF-8?B?UmFkaW0gS3LEjW3DocWZ?= , Linux PM References: <1564643196-7797-1-git-send-email-wanpengli@tencent.com> From: "Rafael J. Wysocki" Organization: Intel Technology Poland Sp. z o. o., KRS 101882, ul. Slowackiego 173, 80-298 Gdansk Message-ID: <7b1e3025-f513-7068-32ac-4830d67b65ac@intel.com> Date: Thu, 1 Aug 2019 18:51:10 +0200 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:60.0) Gecko/20100101 Thunderbird/60.8.0 MIME-Version: 1.0 In-Reply-To: <1564643196-7797-1-git-send-email-wanpengli@tencent.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Content-Language: en-US Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 8/1/2019 9:06 AM, Wanpeng Li wrote: > From: Wanpeng Li > > The downside of guest side polling is that polling is performed even > with other runnable tasks in the host. However, even if poll in kvm > can aware whether or not other runnable tasks in the same pCPU, it > can still incur extra overhead in over-subscribe scenario. Now we can > just enable guest polling when dedicated pCPUs are available. > > Cc: Rafael J. Wysocki > Cc: Paolo Bonzini > Cc: Radim Krčmář > Cc: Marcelo Tosatti > Signed-off-by: Wanpeng Li Paolo, Marcelo, any comments? > --- > drivers/cpuidle/cpuidle-haltpoll.c | 3 ++- > drivers/cpuidle/governors/haltpoll.c | 2 +- > 2 files changed, 3 insertions(+), 2 deletions(-) > > diff --git a/drivers/cpuidle/cpuidle-haltpoll.c b/drivers/cpuidle/cpuidle-haltpoll.c > index 9ac093d..7aee38a 100644 > --- a/drivers/cpuidle/cpuidle-haltpoll.c > +++ b/drivers/cpuidle/cpuidle-haltpoll.c > @@ -53,7 +53,8 @@ static int __init haltpoll_init(void) > > cpuidle_poll_state_init(drv); > > - if (!kvm_para_available()) > + if (!kvm_para_available() || > + !kvm_para_has_hint(KVM_HINTS_REALTIME)) > return 0; > > ret = cpuidle_register(&haltpoll_driver, NULL); > diff --git a/drivers/cpuidle/governors/haltpoll.c b/drivers/cpuidle/governors/haltpoll.c > index 797477b..685c7007 100644 > --- a/drivers/cpuidle/governors/haltpoll.c > +++ b/drivers/cpuidle/governors/haltpoll.c > @@ -141,7 +141,7 @@ static struct cpuidle_governor haltpoll_governor = { > > static int __init init_haltpoll(void) > { > - if (kvm_para_available()) > + if (kvm_para_available() && kvm_para_has_hint(KVM_HINTS_REALTIME)) > return cpuidle_register_governor(&haltpoll_governor); > > return 0;