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 kanga.kvack.org (kanga.kvack.org [205.233.56.17]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 748C4EE57D7 for ; Wed, 31 Dec 2025 15:25:57 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 67C556B0088; Wed, 31 Dec 2025 10:25:56 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 629966B0089; Wed, 31 Dec 2025 10:25:56 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 527AE6B008A; Wed, 31 Dec 2025 10:25:56 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0014.hostedemail.com [216.40.44.14]) by kanga.kvack.org (Postfix) with ESMTP id 41EBC6B0088 for ; Wed, 31 Dec 2025 10:25:56 -0500 (EST) Received: from smtpin22.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay07.hostedemail.com (Postfix) with ESMTP id BA169160465 for ; Wed, 31 Dec 2025 15:25:55 +0000 (UTC) X-FDA: 84280141470.22.2AC8F40 Received: from tor.source.kernel.org (tor.source.kernel.org [172.105.4.254]) by imf29.hostedemail.com (Postfix) with ESMTP id 2F90A120004 for ; Wed, 31 Dec 2025 15:25:54 +0000 (UTC) Authentication-Results: imf29.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b="s/MiUlto"; dmarc=pass (policy=quarantine) header.from=kernel.org; spf=pass (imf29.hostedemail.com: domain of frederic@kernel.org designates 172.105.4.254 as permitted sender) smtp.mailfrom=frederic@kernel.org ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1767194754; a=rsa-sha256; cv=none; b=doE/vDRxwCavzxoI3VZOp215DurkG9bRmcujVMTrPO5LL3H+6zPCkby6jythHBUyZaQjEf ZgzjhFgz7wCVnkqLCVOv3lAOIh4XNnfXq3Dl795xqBsbUYgVxKDOMCmlcvykz49aAYxypf ILwfomoTsp7kTNIVZ1bfhAxFnD8IJec= ARC-Authentication-Results: i=1; imf29.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b="s/MiUlto"; dmarc=pass (policy=quarantine) header.from=kernel.org; spf=pass (imf29.hostedemail.com: domain of frederic@kernel.org designates 172.105.4.254 as permitted sender) smtp.mailfrom=frederic@kernel.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1767194754; h=from:from:sender: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:dkim-signature; bh=2pdAd0KBpKEzOG9SIUhcuMaXAWyHGcb00rsjHnz/GSg=; b=CX4XTvHxN+LII1AqI+MNwPDZsDi6eBy+SeLKsRBX4tzASCPXzEZ6SSTic9jvFOAAGT9CpW 5qzBiww+0e4xXx+4UJadhtWekpDf/ad/7dzU8YHKNbSo/2FZmXx/V7l+SuEiTf2M2mkeNy o+A2gDkhAQ3OHVFGbJdTSaWsE0siyRE= Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by tor.source.kernel.org (Postfix) with ESMTP id 4977B60008; Wed, 31 Dec 2025 15:25:53 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 72AAFC113D0; Wed, 31 Dec 2025 15:25:52 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1767194753; bh=3zCSe0pygUa6B0hxj7uhQQbY3y5VvVFZcfM1W6inRQ8=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=s/MiUltoCktzz6D0wiCqcLuak2qC1jPP+t9uF/Wpp9NyhlhUYJRh4a7DANVK3dS3Y 5TBAIkOcZD7Uzm31uIRNg+KPXeRfrFDCHo5KImNpcVVxeo6H0CXL4UnXKcwUINX/Ll U1vQ9nn+42I+5DqP4hDp4p5tUlokQFV23MAaxYG5+JRLq2JJ2SJ1zhhHcouBH7kW4n j7tnzqkJRksmGaZ82fg+JWX+rpM1JKmvmvmVA/5WAT8i/ukuaEkGR1UaA6w9uc8YRq 7msaf9wYLApzpxDT1X8VKz50GKA//Mk01dWdH2ak+Kw+9n2yKX+4XwtHIVWi3pdEqj QbzdgFhA2MRZA== Date: Wed, 31 Dec 2025 16:25:49 +0100 From: Frederic Weisbecker To: Waiman Long Cc: LKML , Michal =?iso-8859-1?Q?Koutn=FD?= , Andrew Morton , Bjorn Helgaas , Catalin Marinas , Chen Ridong , Danilo Krummrich , "David S . Miller" , Eric Dumazet , Gabriele Monaco , Greg Kroah-Hartman , Ingo Molnar , Jakub Kicinski , Jens Axboe , Johannes Weiner , Lai Jiangshan , Marco Crivellari , Michal Hocko , Muchun Song , Paolo Abeni , Peter Zijlstra , Phil Auld , "Rafael J . Wysocki" , Roman Gushchin , Shakeel Butt , Simon Horman , Tejun Heo , Thomas Gleixner , Vlastimil Babka , Will Deacon , cgroups@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-block@vger.kernel.org, linux-mm@kvack.org, linux-pci@vger.kernel.org, netdev@vger.kernel.org Subject: Re: [PATCH 33/33] doc: Add housekeeping documentation Message-ID: References: <20251224134520.33231-1-frederic@kernel.org> <20251224134520.33231-34-frederic@kernel.org> <370149fc-1624-4a16-ac47-dd9b2dd0ed29@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <370149fc-1624-4a16-ac47-dd9b2dd0ed29@redhat.com> X-Rspamd-Queue-Id: 2F90A120004 X-Rspamd-Server: rspam03 X-Stat-Signature: zj3os54pcdfns8oka15q1u1wo6hj8ztm X-Rspam-User: X-HE-Tag: 1767194754-408084 X-HE-Meta: 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 mbPt4/3F yczyFp0PCTXXOihfOIqEjKguYg36sDf8w11ylr1eyAwEWbu2kx9mea4hY7CKy6VuX7yYWxqIUSb5R2NbFxjsWXW4QrQQQaV/9qWm982Otn1XAad90iJqleovEaP0LYmrf22fNaROWQRQSHMjmx0+hSWXdRcD7WbaJ7JOznNcnzPHNjYsbJuN+Y2WVqw+MxnBJ1K74+NrZOFzvUC3AaPPHNaTDR6ZAu7u+WLP3ScRuJqqfrQmac/2D8px1aQ== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Le Fri, Dec 26, 2025 at 07:39:28PM -0500, Waiman Long a écrit : > On 12/24/25 8:45 AM, Frederic Weisbecker wrote: > > Signed-off-by: Frederic Weisbecker > > --- > > Documentation/core-api/housekeeping.rst | 111 ++++++++++++++++++++++++ > > Documentation/core-api/index.rst | 1 + > > 2 files changed, 112 insertions(+) > > create mode 100644 Documentation/core-api/housekeeping.rst > > > > diff --git a/Documentation/core-api/housekeeping.rst b/Documentation/core-api/housekeeping.rst > > new file mode 100644 > > index 000000000000..e5417302774c > > --- /dev/null > > +++ b/Documentation/core-api/housekeeping.rst > > @@ -0,0 +1,111 @@ > > +====================================== > > +Housekeeping > > +====================================== > > + > > + > > +CPU Isolation moves away kernel work that may otherwise run on any CPU. > > +The purpose of its related features is to reduce the OS jitter that some > > +extreme workloads can't stand, such as in some DPDK usecases. > Nit: "usecases" => "use cases" Are you sure? I'm not a native speaker but at least the kernel has established its use: $ git grep usecase | wc -l 517 > > + > > +The kernel work moved away by CPU isolation is commonly described as > > +"housekeeping" because it includes ground work that performs cleanups, > > +statistics maintainance and actions relying on them, memory release, > > +various deferrals etc... > > + > > +Sometimes housekeeping is just some unbound work (unbound workqueues, > > +unbound timers, ...) that gets easily assigned to non-isolated CPUs. > > +But sometimes housekeeping is tied to a specific CPU and requires > > +elaborated tricks to be offloaded to non-isolated CPUs (RCU_NOCB, remote > > +scheduler tick, etc...). > > + > > +Thus, a housekeeping CPU can be considered as the reverse of an isolated > > +CPU. It is simply a CPU that can execute housekeeping work. There must > > +always be at least one online housekeeping CPU at any time. The CPUs that > > +are not isolated are automatically assigned as housekeeping. > Nit: extra white spaces between "not" and "isolated". Somehow it has disappeared in my tree, some Brunaidh must have fixed that while I was sleeping. That's nice! > > diff --git a/Documentation/core-api/index.rst b/Documentation/core-api/index.rst > > index 5eb0fbbbc323..79fe7735692e 100644 > > --- a/Documentation/core-api/index.rst > > +++ b/Documentation/core-api/index.rst > > @@ -25,6 +25,7 @@ it. > > symbol-namespaces > > asm-annotations > > real-time/index > > + housekeeping.rst > > Data structures and low-level utilities > > ======================================= > Acked-by: Waiman Long Thanks! -- Frederic Weisbecker SUSE Labs