From nobody Tue Dec 16 08:52:35 2025 Received: from galois.linutronix.de (Galois.linutronix.de [193.142.43.55]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 83D0B1E25F7; Tue, 3 Dec 2024 10:44:40 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=193.142.43.55 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1733222683; cv=none; b=GF/QK5uHveXKrCjq4XPdTFKbrtG12KNbv/9LWgWE6t87S/Xh38iXmTC4cjdozieuNw/Jb6b7oFhyJk1g+H5xxgtQa/z1KAmMa3J0YtdwYC4Ip9Okg/yZn8EGfxmCAB0W9m/iTV5xqMjQ05/+ktcgLt2n+QElFokAMoD30qVEUjc= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1733222683; c=relaxed/simple; bh=FhC0QMvWednTfi024xXfypxuEw/KWioLX2xSjo+EHTA=; h=Date:From:To:Subject:Cc:In-Reply-To:References:MIME-Version: Message-ID:Content-Type; b=PL2URLZyZlH7DDzQVfctgoP1N9VWcO5LLd3mVyayUFcz8WvN2PJbD4Vh9oZi6NDV9nC+05MXEF9zIPuY5b2S34YRZMDnm83avzkKXdomDBJO5PmyjhiJnTRFHb6ZBVC7GyUIVe9+bQ89cQTgiJcJAWCmocwDK9xwc8T6kMQVqCg= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linutronix.de; spf=pass smtp.mailfrom=linutronix.de; dkim=pass (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b=y0JaVcLs; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b=NFWiW+Iv; arc=none smtp.client-ip=193.142.43.55 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linutronix.de Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linutronix.de Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="y0JaVcLs"; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="NFWiW+Iv" Date: Tue, 03 Dec 2024 10:44:38 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1733222679; h=from:from:sender:sender:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=rxYH//mQF62YwgLSFiaU0rXVxmQk/9AKtWQpXPuTHL0=; b=y0JaVcLsucKBkMKVmb2/ao31mx5hN+3Hdhq7L017v1Dj4HZeHnCKxhkFTGqxwrDzLKhWNo oOQ5LmBSHKxW1tCV0/RU5MQ9M1cQhenaF0kc2vcL/AHojRkBSChiQqoXpDQdU4eRt6rfg7 1CWg2PypGTO2S/1eKeC73t/G6hy4/Qo2LXRszqf5Ai2sE5INciTiJlJVvxH17VuGj5Sg8b 4r4eR2UHcRc7oU2SixR7+aQysVkVZRbfwz6XTOUTUgpXngpqfX15d8a+7v7pKG55CXuTqO /K8nmV1n2wjEBAqbhS2NHbAXK22P/iqY14FLTQe89uuuMckRtdwoo6kMeLtcig== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1733222679; h=from:from:sender:sender:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=rxYH//mQF62YwgLSFiaU0rXVxmQk/9AKtWQpXPuTHL0=; b=NFWiW+Ivv/y/wC5JBURgVTpbk+BGdtbUEyzWaNW85xSHjxRNvX4gIhR3Pvbjze13fY1b+r lYcnNK6RefU1d7Dw== From: "tip-bot2 for Waiman Long" Sender: tip-bot2@linutronix.de Reply-to: linux-kernel@vger.kernel.org To: linux-tip-commits@vger.kernel.org Subject: [tip: sched/core] sched/isolation: Make "isolcpus=nohz" equivalent to "nohz_full" Cc: Frederic Weisbecker , Waiman Long , "Peter Zijlstra (Intel)" , x86@kernel.org, linux-kernel@vger.kernel.org In-Reply-To: <20241030175253.125248-3-longman@redhat.com> References: <20241030175253.125248-3-longman@redhat.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Message-ID: <173322267814.412.9340788040836130645.tip-bot2@tip-bot2> Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails Precedence: bulk Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable The following commit has been merged into the sched/core branch of tip: Commit-ID: 1174b9344bc7e7989439cad207fcd94eaab028db Gitweb: https://git.kernel.org/tip/1174b9344bc7e7989439cad207fcd94ea= ab028db Author: Waiman Long AuthorDate: Wed, 30 Oct 2024 13:52:51 -04:00 Committer: Peter Zijlstra CommitterDate: Mon, 02 Dec 2024 12:24:28 +01:00 sched/isolation: Make "isolcpus=3Dnohz" equivalent to "nohz_full" The "isolcpus=3Dnohz" boot parameter and flag were used to disable tick when running a single task. Nowsdays, this "nohz" flag is seldomly used as it is included as part of the "nohz_full" parameter. Extend this flag to cover other kernel noises disabled by the "nohz_full" parameter to make them equivalent. This also eliminates the need to use both the "isolcpus" and the "nohz_full" parameters to fully isolated a given set of CPUs. Suggested-by: Frederic Weisbecker Signed-off-by: Waiman Long Signed-off-by: Peter Zijlstra (Intel) Acked-by: Frederic Weisbecker Link: https://lore.kernel.org/r/20241030175253.125248-3-longman@redhat.com --- Documentation/admin-guide/kernel-parameters.txt | 4 +++- kernel/sched/isolation.c | 6 +++++- 2 files changed, 8 insertions(+), 2 deletions(-) diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentatio= n/admin-guide/kernel-parameters.txt index 3872bc6..3fa0b4e 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -2432,7 +2432,9 @@ specified in the flag list (default: domain): =20 nohz - Disable the tick when a single task runs. + Disable the tick when a single task runs as well as + disabling other kernel noises like having RCU callbacks + offloaded. This is equivalent to the nohz_full parameter. =20 A residual 1Hz tick is offloaded to workqueues, which you need to affine to housekeeping through the global diff --git a/kernel/sched/isolation.c b/kernel/sched/isolation.c index 5345e11..6a68632 100644 --- a/kernel/sched/isolation.c +++ b/kernel/sched/isolation.c @@ -209,9 +209,13 @@ static int __init housekeeping_isolcpus_setup(char *st= r) int len; =20 while (isalpha(*str)) { + /* + * isolcpus=3Dnohz is equivalent to nohz_full. + */ if (!strncmp(str, "nohz,", 5)) { str +=3D 5; - flags |=3D HK_FLAG_TICK; + flags |=3D HK_FLAG_TICK | HK_FLAG_WQ | HK_FLAG_TIMER | + HK_FLAG_RCU | HK_FLAG_MISC | HK_FLAG_KTHREAD; continue; }