From patchwork Fri Jan 8 18:05:59 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Rafael J. Wysocki" X-Patchwork-Id: 360029 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=-13.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI, 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 EA7E2C433E0 for ; Fri, 8 Jan 2021 18:07:06 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id AB8B323A6C for ; Fri, 8 Jan 2021 18:07:06 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728649AbhAHSGo (ORCPT ); Fri, 8 Jan 2021 13:06:44 -0500 Received: from cloudserver094114.home.pl ([79.96.170.134]:43634 "EHLO cloudserver094114.home.pl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728442AbhAHSGn (ORCPT ); Fri, 8 Jan 2021 13:06:43 -0500 Received: from 89-64-81-105.dynamic.chello.pl (89.64.81.105) (HELO kreacher.localnet) by serwer1319399.home.pl (79.96.170.134) with SMTP (IdeaSmtpServer 0.83.537) id f8e5a3c0ad700087; Fri, 8 Jan 2021 19:06:01 +0100 From: "Rafael J. Wysocki" To: Peter Zijlstra Cc: Linux PM , LKML , x86 Maintainers , Srinivas Pandruvada , Giovanni Gherdovich , Giovanni Gherdovich Subject: [PATCH] x86: PM: Register syscore_ops for scale invariance Date: Fri, 08 Jan 2021 19:05:59 +0100 Message-ID: <1803209.Mvru99baaF@kreacher> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-pm@vger.kernel.org From: Rafael J. Wysocki On x86 scale invariace tends to be disabled during resume from suspend-to-RAM, because the MPERF or APERF MSR values are not as expected then due to updates taking place after the platform firmware has been invoked to complete the suspend transition. That, of course, is not desirable, especially if the schedutil scaling governor is in use, because the lack of scale invariance causes it to be less reliable. To counter that effect, modify init_freq_invariance() to register a syscore_ops object for scale invariance with the ->resume callback pointing to init_counter_refs() which will run on the CPU starting the resume transition (the other CPUs will be taken care of the "online" operations taking place later). Fixes: e2b0d619b400 ("x86, sched: check for counters overflow in frequency invariant accounting") Signed-off-by: Rafael J. Wysocki --- arch/x86/kernel/smpboot.c | 19 +++++++++++++++++++ 1 file changed, 19 insertions(+) Index: linux-pm/arch/x86/kernel/smpboot.c =================================================================== --- linux-pm.orig/arch/x86/kernel/smpboot.c +++ linux-pm/arch/x86/kernel/smpboot.c @@ -56,6 +56,7 @@ #include #include #include +#include #include #include @@ -2083,6 +2084,23 @@ static void init_counter_refs(void) this_cpu_write(arch_prev_mperf, mperf); } +#ifdef CONFIG_PM_SLEEP +static struct syscore_ops freq_invariance_syscore_ops = { + .resume = init_counter_refs, +}; + +static void register_freq_invariance_syscore_ops(void) +{ + /* Bail out if registered already. */ + if (freq_invariance_syscore_ops.node.prev) + return; + + register_syscore_ops(&freq_invariance_syscore_ops); +} +#else +static inline void register_freq_invariance_syscore_ops(void) {} +#endif + static void init_freq_invariance(bool secondary, bool cppc_ready) { bool ret = false; @@ -2109,6 +2127,7 @@ static void init_freq_invariance(bool se if (ret) { init_counter_refs(); static_branch_enable(&arch_scale_freq_key); + register_freq_invariance_syscore_ops(); pr_info("Estimated ratio of average max frequency by base frequency (times 1024): %llu\n", arch_max_freq_ratio); } else { pr_debug("Couldn't determine max cpu frequency, necessary for scale-invariant accounting.\n");