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=-7.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 D4E43C83003 for ; Wed, 29 Apr 2020 11:30:56 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B03682083B for ; Wed, 29 Apr 2020 11:30:56 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1588159856; bh=ss6jE1Ne0A+UTxaF71hrXRTxoQ2SKD4H4TWKLXh6TPU=; h=References:In-Reply-To:From:Date:Subject:To:Cc:List-ID:From; b=T1quTcQX/gwF+dEo7NHXj8J2GVmgBdFbk+ChZEDrik3lti1bQnY53tYN5+J0Va/vT eSUfNO7a+uCMfso5elVurVQD1hGPjfnUbazcVxharRo0sb4BcR4XfTQzWEQZxE2pjG GZOvbXSRphgLTsUc4A/Uau1OLm/q7ijGj3HmuCis= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727028AbgD2Laz (ORCPT ); Wed, 29 Apr 2020 07:30:55 -0400 Received: from mail-oi1-f196.google.com ([209.85.167.196]:40706 "EHLO mail-oi1-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726836AbgD2Laz (ORCPT ); Wed, 29 Apr 2020 07:30:55 -0400 Received: by mail-oi1-f196.google.com with SMTP id t199so1461892oif.7; Wed, 29 Apr 2020 04:30:54 -0700 (PDT) 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; bh=heSLd4npprlNejenb5g45wkQja+dNAq9zzOcbGYSaDc=; b=WnjWbi3/V2pjffEx2+R4V6Llf7vZNCwlWzTK8tTRktZTEohSbxSafSYTz3Dh8O0C7c Zbfl+nPHx2ZnpvtLIeM7/AWRE2Bli79IenKso5MhO3rwCJGp+ka9f4xW7HMVbmbYyi/+ ZUWAYm9SmVRh3I7hopGRlCfEa6JsjTZrpf8l9PCl4hO2yT5QGqYRAMJXeBLYia33MpHJ zEaw/UqgFOGXMsryhAfrtQK/L+SRzJB//CmQhH5c2ATnEQhkBj1fDkkm3zi+imPNGIzW oX2kbORf6wPhlqahqUkBAqsqUdRUAep8LbeyohPmAtJGGW80HxN4XPGxtaDtQP6OO5bN m1cQ== X-Gm-Message-State: AGi0PuYMHY3idDJXetPKuqRjvv9lD5Kmb3Ud4CBOjs67vgJ4SRFwXRfl pKZoecjqIqzyAIhgtNQPAx59tBXzdCNCst1thL4= X-Google-Smtp-Source: APiQypL2VJCwN8MUXctgcgltHppclMxwktU0GxZbf5xmOkgYPSjcfg5KRmGgzF7wKzviwEGyKJ4dDwf4LmIZiY4bQcY= X-Received: by 2002:aca:c441:: with SMTP id u62mr1351091oif.110.1588159854355; Wed, 29 Apr 2020 04:30:54 -0700 (PDT) MIME-Version: 1.0 References: <20200428132450.24901-1-ggherdovich@suse.cz> <20200428132450.24901-3-ggherdovich@suse.cz> In-Reply-To: <20200428132450.24901-3-ggherdovich@suse.cz> From: "Rafael J. Wysocki" Date: Wed, 29 Apr 2020 13:30:43 +0200 Message-ID: Subject: Re: [PATCH 2/2] x86, sched: Bail out of frequency invariance if turbo frequency is unknown To: Giovanni Gherdovich Cc: Srinivas Pandruvada , Thomas Gleixner , Ingo Molnar , Peter Zijlstra , Borislav Petkov , Len Brown , "Rafael J . Wysocki" , "the arch/x86 maintainers" , Linux PM , Linux Kernel Mailing List , Ricardo Neri , Linus Torvalds Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Apr 28, 2020 at 3:25 PM Giovanni Gherdovich wrote: > > There may be CPUs that support turbo boost but don't declare any turbo > ratio, i.e. their MSR_TURBO_RATIO_LIMIT is all zeroes. In that condition > scale-invariant calculations can't be performed. > > Signed-off-by: Giovanni Gherdovich > Suggested-by: Ricardo Neri > Fixes: 1567c3e3467c ("x86, sched: Add support for frequency invariance") Acked-by: Rafael J. Wysocki > --- > arch/x86/kernel/smpboot.c | 6 ++++-- > 1 file changed, 4 insertions(+), 2 deletions(-) > > diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c > index 4718f29a3065..ab2a0df7d1fb 100644 > --- a/arch/x86/kernel/smpboot.c > +++ b/arch/x86/kernel/smpboot.c > @@ -1991,9 +1991,11 @@ static bool intel_set_max_freq_ratio(void) > /* > * Some hypervisors advertise X86_FEATURE_APERFMPERF > * but then fill all MSR's with zeroes. > + * Some CPUs have turbo boost but don't declare any turbo ratio > + * in MSR_TURBO_RATIO_LIMIT. > */ > - if (!base_freq) { > - pr_debug("Couldn't determine cpu base frequency, necessary for scale-invariant accounting.\n"); > + if (!base_freq || !turbo_freq) { > + pr_debug("Couldn't determine cpu base or turbo frequency, necessary for scale-invariant accounting.\n"); > return false; > } > > -- > 2.16.4 >