From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) (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 A478A15B3 for ; Sun, 11 Feb 2024 01:46:46 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.129.124 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1707616008; cv=none; b=CfsfDMd2dHGjbS1SJuSJsbEEKGvHYl61zpJJViFvleiS8jwJVJN2NAFwIiL4m53Cs0sMF3ERadp3VmgleRt/eSaagxdcWVxy+rr8ZCl1Tug0mZX8ITi1hYFx6k+ZIVrUTTvi9QFEfJ0DwpCD7QXPWGnInFsctZ+b+SNi/s9AyI0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1707616008; c=relaxed/simple; bh=BQmjpW0I5tJ8/1nqzqWJxFSuGQt107l1mhgaSnsMkJI=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=h2UFF6DhbiB1Ge8f4Ddq5irnX1Qal8PdHfBz9BA96QcnFwgHF3kLk3ZJj7L2lC0Ou0p8/l2xxWnpAK5yi0nvaISBTsjfeI/iW0xl5vhbOb8J0zmxNQ0QVZKPoYglpKITjQbPaxXu+rKTee3lol70+vwOGbRX/npat3qKShpQ8QY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none 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=WpISfuCO; arc=none smtp.client-ip=170.10.129.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none 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="WpISfuCO" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1707616005; 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=fGLK4dJX5e1tF4UUiUtCFTTT+Sp7JjuwMt77i6yrPM0=; b=WpISfuCO24GsuMHjjxSWXyYQCBA1IprpwdnBAHZIDj3UeW4NVOzx9fVVecy1rj9HjlhZ+7 I3rLhWjh1WTRKb9E1Dz6rdPdNGmfuAqc0MXzEyP1Ia8EL041qfNOG0NH8EhXY9yknLdMV9 fnL+FrmwKaiWTPLGQdAUdEQeEyDdzhQ= Received: from mimecast-mx02.redhat.com (mx-ext.redhat.com [66.187.233.73]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-571-yiTLxjd_N9GMU2JQXIMtGQ-1; Sat, 10 Feb 2024 20:46:41 -0500 X-MC-Unique: yiTLxjd_N9GMU2JQXIMtGQ-1 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.rdu2.redhat.com [10.11.54.3]) (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 mimecast-mx02.redhat.com (Postfix) with ESMTPS id B7C7E38212CD; Sun, 11 Feb 2024 01:46:40 +0000 (UTC) Received: from [10.22.16.18] (unknown [10.22.16.18]) by smtp.corp.redhat.com (Postfix) with ESMTP id 99E84111CD4C; Sun, 11 Feb 2024 01:46:34 +0000 (UTC) Message-ID: <099a0310-6805-4ad5-aa99-2589e768acd6@redhat.com> Date: Sat, 10 Feb 2024 20:46:34 -0500 Precedence: bulk X-Mailing-List: linux-doc@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [RFC PATCH 0/8] cgroup/cpuset: Support RCU_NOCB on isolated partitions Content-Language: en-US To: paulmck@kernel.org Cc: Tejun Heo , Zefan Li , Johannes Weiner , Frederic Weisbecker , Jonathan Corbet , Neeraj Upadhyay , Joel Fernandes , Josh Triplett , Boqun Feng , Steven Rostedt , Mathieu Desnoyers , Lai Jiangshan , Zqiang , Davidlohr Bueso , Shuah Khan , cgroups@vger.kernel.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, rcu@vger.kernel.org, linux-kselftest@vger.kernel.org, Mrunal Patel , Ryan Phillips , Brent Rowsell , Peter Hunt , Cestmir Kalina , Nicolas Saenz Julienne , Alex Gladkov , Marcelo Tosatti , Phil Auld , Paul Gortmaker , Daniel Bristot de Oliveira , Juri Lelli , Peter Zijlstra , Costa Shulyupin References: <20240117163511.88173-1-longman@redhat.com> From: Waiman Long In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 3.4.1 on 10.11.54.3 On 1/19/24 05:24, Paul E. McKenney wrote: > On Wed, Jan 17, 2024 at 11:35:03AM -0500, Waiman Long wrote: >> This patch series is based on the RFC patch from Frederic [1]. Instead >> of offering RCU_NOCB as a separate option, it is now lumped into a >> root-only cpuset.cpus.isolation_full flag that will enable all the >> additional CPU isolation capabilities available for isolated partitions >> if set. RCU_NOCB is just the first one to this party. Additional dynamic >> CPU isolation capabilities will be added in the future. >> >> The first 2 patches are adopted from Federic with minor twists to fix >> merge conflicts and compilation issue. The rests are for implementing >> the new cpuset.cpus.isolation_full interface which is essentially a flag >> to globally enable or disable full CPU isolation on isolated partitions. >> On read, it also shows the CPU isolation capabilities that are currently >> enabled. RCU_NOCB requires that the rcu_nocbs option be present in >> the kernel boot command line. Without that, the rcu_nocb functionality >> cannot be enabled even if the isolation_full flag is set. So we allow >> users to check the isolation_full file to verify that if the desired >> CPU isolation capability is enabled or not. >> >> Only sanity checking has been done so far. More testing, especially on >> the RCU side, will be needed. > There has been some discussion of simplifying the (de-)offloading code > to handle only offline CPUs. Along with some discussion of eliminating > the (de-)offloading capability altogehter. > > We clearly should converge on the capability to be provided before > exposing this to userspace. ;-) Would you mind giving me a pointer to the discussion of simplifying the de-offloading code to  handle only offline CPUs? Thanks, Longman