From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) (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 8F29D3EB0F2 for ; Thu, 15 Oct 2026 16:00:38 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.133.124 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1792080049; cv=none; b=EN1bMbn7IwMg97XhMkI24muD9IySskW1IZPeAprj40fdHOHm4fMBb/sAf8ZK4qd9lVNYHtlDlVnWGMJCcNAay7hn1VdjF4gJhBLJwID2Kvv4h0IdaNWZXLrA5ltEbfXVAPRh4G58pZKHe3tnSthP6yLbop1hw8+I83CHobluwlM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1792080049; c=relaxed/simple; bh=Q8kItJVsWWmsGFjBSW5i/8M3gtH3LqujXVXYI7nhe84=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=s//hIT0nO+/9T14VaHSb8EkKXQdOZTiCUVsJ9OjK5jTHzYzIkpiL1+s6mHtZpj4p71TtU/SYmPlFCuEblsxC7kliZ2D4OcjV+1VyqZ4rKWTEEHYt5hRXL0U5uSr7FaozhFquS6+NC5Fg8IZpNcnHqpV2OBLHpMZYTwpvaCghn6I= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=Z17711Tz; arc=none smtp.client-ip=170.10.133.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="Z17711Tz" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1792080037; 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: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=69I5z43SNpWpQOCMT7NnKODZLMO9VTaM22ZCdgeumX0=; b=Z17711TznNkCKzeF57h7djhp+4xvTRaD3XwIb9pz8F8OJf9wsgdzDuSjXnMJLwc1jnfCdo sRDObDpcKGY2dOCmNv2wG4USPlvmobVFAUnzS/n8Kj1Z7/O3SIKWRTcS2G6jhNaEE4C7vV KUHZ1IK5W5dU2YxGvm18JcrwmVJnD7E= Received: from mx-prod-mc-03.mail-002.prod.us-west-2.aws.redhat.com (ec2-54-186-198-63.us-west-2.compute.amazonaws.com [54.186.198.63]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-594-x93ERWNBN8yYwCEjMNbQuw-1; Thu, 15 Oct 2026 16:00:33 +0000 X-MC-Unique: x93ERWNBN8yYwCEjMNbQuw-1 X-Mimecast-MFC-AGG-ID: x93ERWNBN8yYwCEjMNbQuw_1792080031 Received: from mx-prod-int-06.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-06.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.93]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-03.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 668C01944B00; Thu, 15 Oct 2026 16:00:30 +0000 (UTC) Received: from [100.91.18.181] (headnet03.pony-001.prod.iad2.dc.redhat.com [10.2.32.114]) by mx-prod-int-06.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id 7963D180057F; Thu, 15 Oct 2026 16:00:26 +0000 (UTC) Message-ID: <8d10bb84-d312-4be0-8c43-ddd602850a1d@redhat.com> Date: Thu, 15 Oct 2026 12:00:25 -0400 Precedence: bulk X-Mailing-List: linux-trace-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [RFC PATCH 0/2] tick/nohz: Add runtime control of non-idle tick suppression To: Peng Wang , Anna-Maria Behnsen , Frederic Weisbecker , Ingo Molnar , Thomas Gleixner Cc: Greg Kroah-Hartman , "Rafael J . Wysocki" , Danilo Krummrich , Steven Rostedt , Masami Hiramatsu , Mathieu Desnoyers , Peter Zijlstra , Tejun Heo , He Rongguang , linux-kernel@vger.kernel.org, linux-api@vger.kernel.org, driver-core@lists.linux.dev, linux-trace-kernel@vger.kernel.org, cgroups@vger.kernel.org References: From: Waiman Long In-Reply-To: X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.93 X-Mimecast-MFC-PROC-ID: 1cm8eOAw_jNrwuh44Cq7fYrHR134c5Y4-pg3BLdi5FA_1792080031 X-Mimecast-Originator: redhat.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 10/15/26 8:43 AM, Peng Wang wrote: > Workloads and their need for periodic ticks can change after boot. > This series lets userspace choose at runtime which CPUs in the boot-time > nohz_full set retain the non-idle scheduler tick and which are permitted > to stop it, while preserving the existing isolation configuration. > > The first patch adds a per-CPU tick dependency; the second exposes a > sysfs CPU list. Permission defaults to all nohz_full CPUs. Revocation > uses the existing asynchronous kick. Idle tick suppression is unchanged, > and policy persists across hotplug. So you are basically setting up more nohz_full CPUs than the system actually needs to use at the moment and so want to disable nohz/tick part of nohz_full CPUs that don't need it. Can you elaborate more about the problems solve by introducing this new behavior? > > Existing cpuset partition modes do not express this independent tick > policy. Feedback on the proposed interface is welcome. We are planning to eventually extend cpuset partition mode to change nohz_full at runtime. This is still a work in progress. Regards, Longman > > Thanks, > Peng > > Peng Wang (2): > tick/nohz: Add a policy dependency for full dynticks > cpu: Add sysfs control of full dynticks policy > > .../ABI/testing/sysfs-devices-system-cpu | 40 ++++++++++++ > drivers/base/cpu.c | 46 ++++++++++++++ > include/linux/tick.h | 8 ++- > include/trace/events/timer.h | 3 +- > kernel/time/tick-sched.c | 62 +++++++++++++++++++ > 5 files changed, 156 insertions(+), 3 deletions(-) > > > base-commit: 0fcb05b72344f40806cbe810de8872f1698bf053