From patchwork Fri Apr 15 19:19:50 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Thomas Gleixner X-Patchwork-Id: 12815247 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 14E0FC433FE for ; Fri, 15 Apr 2022 19:19:56 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1347781AbiDOTWW (ORCPT ); Fri, 15 Apr 2022 15:22:22 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37524 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S240222AbiDOTWV (ORCPT ); Fri, 15 Apr 2022 15:22:21 -0400 Received: from galois.linutronix.de (Galois.linutronix.de [IPv6:2a0a:51c0:0:12e:550::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 19E193E5F2; Fri, 15 Apr 2022 12:19:52 -0700 (PDT) Message-ID: <20220415161206.419880163@linutronix.de> DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1650050390; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: references:references; bh=7jYVnFbvS1wwhh/xx/6Po12K0RSM7iGrhAKv7OZOS5Y=; b=ibn5CEoItB13fo1TcH5WhfU42+e2Hv5azziNbxi3BJLqgRMgXTUfaxkrIDyi7VxobycJ95 yhY+NjHwSBhn0nbKSN7UqLsM2UPHKcN12SZEGbPGrPBaZkflkaBx1jEHxOuTcE9EcZg6k5 9yEFPSr+4hZns3aIghYzqDXDK3j2jCDfnHWxVa8Hn9BnArKxdX4agbF/RtDtkrSkxskjU0 U7O6KqclwS/PJg6lEIDEB5iyKgzAb+gEEVXgoiSMBNnBApYvKW8wZ1vMNRFTcyp83Wxvt0 DqX6lrrCnMT1DPW6+SpHjfGBJonoWci049BZHKLYL6XS082qhKrLuUNphH2wUg== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1650050390; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: references:references; bh=7jYVnFbvS1wwhh/xx/6Po12K0RSM7iGrhAKv7OZOS5Y=; b=J+OlnM5CPKWmBhZNPQx401r0dC9MlMfnI44nxQy0clF2y+zEZeX+iWc0sDj82hsDNw4g1u Gl8cYQfpED9qenBQ== From: Thomas Gleixner To: LKML Cc: x86@kernel.org, "Rafael J. Wysocki" , linux-pm@vger.kernel.org, Eric Dumazet , "Paul E. McKenney" Subject: [patch 01/10] x86/aperfmperf: Dont wake idle CPUs in arch_freq_get_on_cpu() References: <20220415133356.179706384@linutronix.de> MIME-Version: 1.0 Date: Fri, 15 Apr 2022 21:19:50 +0200 (CEST) Precedence: bulk List-ID: X-Mailing-List: linux-pm@vger.kernel.org aperfmperf_get_khz() already excludes idle CPUs from APERF/MPERF sampling and that's a reasonable decision. There is no point in sending up to two IPIs to an idle CPU just because someone reads a sysfs file. Signed-off-by: Thomas Gleixner Acked-by: Rafael J. Wysocki --- arch/x86/kernel/cpu/aperfmperf.c | 3 +++ 1 file changed, 3 insertions(+) --- a/arch/x86/kernel/cpu/aperfmperf.c +++ b/arch/x86/kernel/cpu/aperfmperf.c @@ -139,6 +139,9 @@ unsigned int arch_freq_get_on_cpu(int cp if (!housekeeping_cpu(cpu, HK_TYPE_MISC)) return 0; + if (rcu_is_idle_cpu(cpu)) + return 0; + if (aperfmperf_snapshot_cpu(cpu, ktime_get(), true)) return per_cpu(samples.khz, cpu);