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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id A760FC433F5 for ; Tue, 19 Apr 2022 15:35:30 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1353859AbiDSPiK (ORCPT ); Tue, 19 Apr 2022 11:38:10 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:41130 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1354055AbiDSPh5 (ORCPT ); Tue, 19 Apr 2022 11:37:57 -0400 Received: from mail-yb1-f175.google.com (mail-yb1-f175.google.com [209.85.219.175]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B69DAB86D; Tue, 19 Apr 2022 08:35:08 -0700 (PDT) Received: by mail-yb1-f175.google.com with SMTP id d19so3311109ybc.5; Tue, 19 Apr 2022 08:35:08 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=cYK+mSus6lKX2J8+IsFXmSmlA2Ef7OVLzpY5/HdayQU=; b=1vWRS+SKfTOMQ41+nkvzPNmMv+QmXfavjtNUEGor68WJBuAnaVv46NdV1cVX4sSSdT n/fFdaEzeQle88onvg7B9xhTojuz2uY/AehxdyZ3E7rjUJGo1to0zLBSKrWA93qm70D2 P6dG01Swbug1DQdbcGjaBGJZ6gEckf8Zt2yybwigRF2UCH9UVtXTf1Ckm2llO0BhhuxM XgNOdiJzBVdNZOJNQZdl9CRyluUpr27vYbk0cqhUYX6+VgQSS0CZH68QhjYGuUAyZ5uZ fGNFnH3XZ1s18gZMgha2GMCLCQu6SAL9KPW2rgH9GrQ8PE7ZfNLCepB5SVyRiBIs2d83 XYqg== X-Gm-Message-State: AOAM531wHevyrykZ3ph+hmrAPfApqRKL1tikxYXX2kCpBKRzsZOOQFfQ DQsWBRiLjQ/ihSzc9z4j4RZpuL1FgBqDdMpok+w= X-Google-Smtp-Source: ABdhPJwDmO9+9C24sXjAZavu7CzsApnTtTT7vU16/f1c9ZI+vpUjXzYeo8Lw4VND0xYUMo6HcRe2v4Fqm3mIsA16qcw= X-Received: by 2002:a25:ac9b:0:b0:641:3c32:bee7 with SMTP id x27-20020a25ac9b000000b006413c32bee7mr14411799ybi.633.1650382507645; Tue, 19 Apr 2022 08:35:07 -0700 (PDT) MIME-Version: 1.0 References: <20220415133356.179706384@linutronix.de> <20220415161206.419880163@linutronix.de> In-Reply-To: <20220415161206.419880163@linutronix.de> From: "Rafael J. Wysocki" Date: Tue, 19 Apr 2022 17:34:56 +0200 Message-ID: Subject: Re: [patch 01/10] x86/aperfmperf: Dont wake idle CPUs in arch_freq_get_on_cpu() To: Thomas Gleixner Cc: LKML , "the arch/x86 maintainers" , "Rafael J. Wysocki" , Linux PM , Eric Dumazet , "Paul E. McKenney" Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Apr 15, 2022 at 9:19 PM Thomas Gleixner wrote: > > 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); > >