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=-3.7 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED 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 459A6C3A5A3 for ; Thu, 29 Aug 2019 12:16:17 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 1341F2339E for ; Thu, 29 Aug 2019 12:16:17 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="QrFj1YIF" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727906AbfH2MQJ (ORCPT ); Thu, 29 Aug 2019 08:16:09 -0400 Received: from mail-oi1-f196.google.com ([209.85.167.196]:39488 "EHLO mail-oi1-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727025AbfH2MQJ (ORCPT ); Thu, 29 Aug 2019 08:16:09 -0400 Received: by mail-oi1-f196.google.com with SMTP id 16so2339542oiq.6; Thu, 29 Aug 2019 05:16:08 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc:content-transfer-encoding; bh=ZJ52Xwnuz86LA+OndXIVKURqQP4L9RyMWjskSBWJHfk=; b=QrFj1YIF09DrXwvt39jlEC1w2Frhv2LdhQUAWc60IHe4VMj5bieyIaP365ob6DgLtp 3DtgykIGgmh7DD0JhhmkeSsOlZKewX5DRq9rrgHmmCmicxGieAr2Hq46INW1O1uCNMm9 09xQ/6zLKIRpRD/8NrHHDW/GH2RoMQ3lhrzlT4EHsSTsqCq8KMWwPS665zb+bjdsp0Nr UdNckSqBFGoycBaCeYfbhQBei52da8py9Xxm65qJGYo7QM2Kv4GZ6YTis/BQN1htKDFa osjx/O7xc6RTquVh9ShigWMmQhqfnYt9Z/bDm7rLbUBoASnaKG/b05PbafSqLHc+Gdcf xGSw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc:content-transfer-encoding; bh=ZJ52Xwnuz86LA+OndXIVKURqQP4L9RyMWjskSBWJHfk=; b=OHKLEcI1dwHXzLwGy809q7Q8DV+eWoowQ31upYbOv4tUmHlBm7j8OUy1TsCs3TlT4q iejA9lZZd7wlk3oKpLny6H4rGsprn9CMuJP8CF6J20/M3frMGcLrahsl2Z2Qrn/MmYfB 1m0cl6jkOJliaQxsoiEbwg5IIuPoCZKLLmiL3JS3mTUeZk5h2R3liROA3/3qFX+5GRbO d7tSINMhZSCqzWUfvz0fUGr/ZeH7If2nWK9fkbpIdGlnoesV651DhxohSz9mN547gWJ8 dq56Sr/Fen/zsXIhLTspHjAIbM9TwrTyOTA1MGJXrvNfutLQkfS0rB6ASPuQ6baVGv8D y6WQ== X-Gm-Message-State: APjAAAXTGj+8HfPPrZ+oKFZpcH5xd+2wgJOQNDbk1vIWUKH2yF8u2G8e SfvngBiYmrxjN1qx7uVXojJacYm1NiQ+74/WQQA= X-Google-Smtp-Source: APXvYqyCRNfos6DQxO12QxxXYeJRgZJKDcoFbYZ2ozhLfSA0XcHv9fgr+95Faw7ADONtBP2NBanXzk/LFdxwX/wkHQU= X-Received: by 2002:a54:488e:: with SMTP id r14mr6328224oic.174.1567080967669; Thu, 29 Aug 2019 05:16:07 -0700 (PDT) MIME-Version: 1.0 References: <7b1e3025-f513-7068-32ac-4830d67b65ac@intel.com> <20190803202058.GA9316@amt.cnet> <20190826204045.GA24697@amt.cnet> <20190828143916.GA13725@amt.cnet> <20190829120422.GC4949@amt.cnet> In-Reply-To: <20190829120422.GC4949@amt.cnet> From: Wanpeng Li Date: Thu, 29 Aug 2019 20:16:41 +0800 Message-ID: Subject: Re: [PATCH] cpuidle-haltpoll: Enable kvm guest polling when dedicated physical CPUs are available To: Marcelo Tosatti Cc: "Rafael J. Wysocki" , Paolo Bonzini , "Rafael J. Wysocki" , LKML , kvm , =?UTF-8?B?UmFkaW0gS3LEjW3DocWZ?= , Linux PM , "Michael S. Tsirkin" Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Sender: linux-pm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-pm@vger.kernel.org On Thu, 29 Aug 2019 at 20:04, Marcelo Tosatti wrote: > > On Thu, Aug 29, 2019 at 01:37:35AM +0200, Rafael J. Wysocki wrote: > > On Wed, Aug 28, 2019 at 4:39 PM Marcelo Tosatti w= rote: > > > > > > On Wed, Aug 28, 2019 at 10:45:44AM +0200, Rafael J. Wysocki wrote: > > > > On Wed, Aug 28, 2019 at 10:34 AM Wanpeng Li w= rote: > > > > > > > > > > On Tue, 27 Aug 2019 at 08:43, Wanpeng Li wr= ote: > > > > > > > > > > > > Cc Michael S. Tsirkin, > > > > > > On Tue, 27 Aug 2019 at 04:42, Marcelo Tosatti wrote: > > > > > > > > > > > > > > On Tue, Aug 13, 2019 at 08:55:29AM +0800, Wanpeng Li wrote: > > > > > > > > On Sun, 4 Aug 2019 at 04:21, Marcelo Tosatti wrote: > > > > > > > > > > > > > > > > > > On Thu, Aug 01, 2019 at 06:54:49PM +0200, Paolo Bonzini w= rote: > > > > > > > > > > On 01/08/19 18:51, Rafael J. Wysocki wrote: > > > > > > > > > > > On 8/1/2019 9:06 AM, Wanpeng Li wrote: > > > > > > > > > > >> From: Wanpeng Li > > > > > > > > > > >> > > > > > > > > > > >> The downside of guest side polling is that polling i= s 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 sce= nario. Now we can > > > > > > > > > > >> just enable guest polling when dedicated pCPUs are a= vailable. > > > > > > > > > > >> > > > > > > > > > > >> Cc: Rafael J. Wysocki > > > > > > > > > > >> Cc: Paolo Bonzini > > > > > > > > > > >> Cc: Radim Kr=C4=8Dm=C3=A1=C5=99 > > > > > > > > > > >> Cc: Marcelo Tosatti > > > > > > > > > > >> Signed-off-by: Wanpeng Li > > > > > > > > > > > > > > > > > > > > > > Paolo, Marcelo, any comments? > > > > > > > > > > > > > > > > > > > > Yes, it's a good idea. > > > > > > > > > > > > > > > > > > > > Acked-by: Paolo Bonzini > > > > > > > > > > Hi Marcelo, > > > > > > > > > > If you don't have more concern, I guess Rafael can apply this pat= ch > > > > > now since the merge window is not too far. > > > > > > > > I will likely queue it up later today and it will go to linux-next > > > > early next week. > > > > > > > > Thanks! > > > > > > NACK patch. > > > > I got an ACK from Paolo on it, though. Convince Paolo to withdraw his > > ACK if you want it to not be applied. > > > > > Just don't load the haltpoll driver. > > > > And why would that be better? > > Split the group of all kvm users in two: overcommit group and non-overcom= mit > group. > > Current situation regarding haltpoll driver is: > > overcommit group: haltpoll driver is not loaded by default, they are > happy. > > non overcommit group: boots without "realtime hints" flag, loads haltpoll= driver, > happy. > > Situation with patch above: > > overcommit group: haltpoll driver is not loaded by default, they are > happy. > > non overcommit group: boots without "realtime hints" flag, haltpoll drive= r > cannot be loaded. non overcommit group, if they don't care latency/performance, they don't need to enable haltpoll, "realtime hints" etc. Otherwise, they should better tune. Regards, Wanpeng Li