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=-6.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS 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 46515C432C3 for ; Fri, 15 Nov 2019 10:45:06 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 2715020748 for ; Fri, 15 Nov 2019 10:45:06 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727142AbfKOKpF (ORCPT ); Fri, 15 Nov 2019 05:45:05 -0500 Received: from cloudserver094114.home.pl ([79.96.170.134]:42681 "EHLO cloudserver094114.home.pl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727022AbfKOKpF (ORCPT ); Fri, 15 Nov 2019 05:45:05 -0500 Received: from 79.184.253.153.ipv4.supernova.orange.pl (79.184.253.153) (HELO kreacher.localnet) by serwer1319399.home.pl (79.96.170.134) with SMTP (IdeaSmtpServer 0.83.292) id fddc515768e678ae; Fri, 15 Nov 2019 11:45:02 +0100 From: "Rafael J. Wysocki" To: Zhenzhong Duan Cc: linux-kernel@vger.kernel.org, pbonzini@redhat.com, rkrcmar@redhat.com, rafael.j.wysocki@intel.com, joao.m.martins@oracle.com, mtosatti@redhat.com, kvm@vger.kernel.org, linux-pm@vger.kernel.org Subject: Re: [PATCH RESEND v2 3/4] cpuidle-haltpoll: ensure cpu_halt_poll_us in right scope Date: Fri, 15 Nov 2019 11:45:01 +0100 Message-ID: <6161954.sKiXg2khOt@kreacher> In-Reply-To: <1573041302-4904-4-git-send-email-zhenzhong.duan@oracle.com> References: <1573041302-4904-1-git-send-email-zhenzhong.duan@oracle.com> <1573041302-4904-4-git-send-email-zhenzhong.duan@oracle.com> MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="us-ascii" Sender: linux-pm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-pm@vger.kernel.org On Wednesday, November 6, 2019 12:55:01 PM CET Zhenzhong Duan wrote: > As user can adjust guest_halt_poll_grow_start and guest_halt_poll_ns > which leads to cpu_halt_poll_us beyond the two boundaries. This patch > ensures cpu_halt_poll_us in that scope. > > If guest_halt_poll_shrink is 0, shrink the cpu_halt_poll_us to > guest_halt_poll_grow_start instead of 0. To disable poll we can set > guest_halt_poll_ns to 0. > > If user wrongly set guest_halt_poll_grow_start > guest_halt_poll_ns > 0, > guest_halt_poll_ns take precedency and poll time is a fixed value of > guest_halt_poll_ns. > > Signed-off-by: Zhenzhong Duan > --- > drivers/cpuidle/governors/haltpoll.c | 28 +++++++++++++--------------- > 1 file changed, 13 insertions(+), 15 deletions(-) > > diff --git a/drivers/cpuidle/governors/haltpoll.c b/drivers/cpuidle/governors/haltpoll.c > index 660859d..4a39df4 100644 > --- a/drivers/cpuidle/governors/haltpoll.c > +++ b/drivers/cpuidle/governors/haltpoll.c > @@ -97,32 +97,30 @@ static int haltpoll_select(struct cpuidle_driver *drv, > > static void adjust_poll_limit(struct cpuidle_device *dev, unsigned int block_us) > { > - unsigned int val; > + unsigned int val = dev->poll_limit_ns; Not necessary to initialize it here. > u64 block_ns = block_us*NSEC_PER_USEC; > > /* Grow cpu_halt_poll_us if > - * cpu_halt_poll_us < block_ns < guest_halt_poll_us > + * cpu_halt_poll_us < block_ns <= guest_halt_poll_us You could update the comment to say "dev->poll_limit_ns" instead of "cpu_halt_poll_us" while at it. > */ > - if (block_ns > dev->poll_limit_ns && block_ns <= guest_halt_poll_ns) { > + if (block_ns > dev->poll_limit_ns && block_ns <= guest_halt_poll_ns && > + guest_halt_poll_grow) The "{" brace is still needed as per the coding style and I'm not sure why to avoid guest_halt_poll_grow equal to zero here? > val = dev->poll_limit_ns * guest_halt_poll_grow; > - > - if (val < guest_halt_poll_grow_start) > - val = guest_halt_poll_grow_start; > - if (val > guest_halt_poll_ns) > - val = guest_halt_poll_ns; > - > - dev->poll_limit_ns = val; > - } else if (block_ns > guest_halt_poll_ns && > - guest_halt_poll_allow_shrink) { > + else if (block_ns > guest_halt_poll_ns && > + guest_halt_poll_allow_shrink) { > unsigned int shrink = guest_halt_poll_shrink; > > - val = dev->poll_limit_ns; > if (shrink == 0) > - val = 0; > + val = guest_halt_poll_grow_start; That's going to be corrected below, so the original code would be fine. > else > val /= shrink; Here you can do val = dev->poll_limit_ns / shrink; > - dev->poll_limit_ns = val; > } > + if (val < guest_halt_poll_grow_start) > + val = guest_halt_poll_grow_start; Note that guest_halt_poll_grow_start is in us (as per the comment next to its definition and the initial value). That is a bug in the original code too, but anyway. > + if (val > guest_halt_poll_ns) > + val = guest_halt_poll_ns; > + > + dev->poll_limit_ns = val; > } > > /** >