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=-5.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, 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 32B45C3A59F for ; Thu, 29 Aug 2019 12:04:47 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 0D3952166E for ; Thu, 29 Aug 2019 12:04:47 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726973AbfH2MEq (ORCPT ); Thu, 29 Aug 2019 08:04:46 -0400 Received: from mx1.redhat.com ([209.132.183.28]:41844 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725990AbfH2MEq (ORCPT ); Thu, 29 Aug 2019 08:04:46 -0400 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.phx2.redhat.com [10.5.11.23]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 5099649; Thu, 29 Aug 2019 12:04:45 +0000 (UTC) Received: from amt.cnet (ovpn-112-4.gru2.redhat.com [10.97.112.4]) by smtp.corp.redhat.com (Postfix) with ESMTP id 85FC619D7A; Thu, 29 Aug 2019 12:04:41 +0000 (UTC) Received: from amt.cnet (localhost [127.0.0.1]) by amt.cnet (Postfix) with ESMTP id 8408F105140; Thu, 29 Aug 2019 09:04:24 -0300 (BRT) Received: (from marcelo@localhost) by amt.cnet (8.14.7/8.14.7/Submit) id x7TC4Mmr010498; Thu, 29 Aug 2019 09:04:22 -0300 Date: Thu, 29 Aug 2019 09:04:22 -0300 From: Marcelo Tosatti To: "Rafael J. Wysocki" Cc: Wanpeng Li , Paolo Bonzini , "Rafael J. Wysocki" , LKML , kvm , Radim =?utf-8?B?S3LEjW3DocWZ?= , Linux PM , "Michael S. Tsirkin" Subject: Re: [PATCH] cpuidle-haltpoll: Enable kvm guest polling when dedicated physical CPUs are available Message-ID: <20190829120422.GC4949@amt.cnet> References: <7b1e3025-f513-7068-32ac-4830d67b65ac@intel.com> <20190803202058.GA9316@amt.cnet> <20190826204045.GA24697@amt.cnet> <20190828143916.GA13725@amt.cnet> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: User-Agent: Mutt/1.5.21 (2010-09-15) X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.6.2 (mx1.redhat.com [10.5.110.71]); Thu, 29 Aug 2019 12:04:45 +0000 (UTC) Sender: linux-pm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-pm@vger.kernel.org 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 wrote: > > > > 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 wrote: > > > > > > > > On Tue, 27 Aug 2019 at 08:43, Wanpeng Li wrote: > > > > > > > > > > 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 wrote: > > > > > > > > > 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 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? > > > > > > > > > > > > > > > > > > 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 patch > > > > 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-overcommit 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 driver cannot be loaded.