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a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1774949013; bh=DZoalaXDsEVeM0Ax8G7Y4p1iyVXciubggMHPstxJdjM=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=VWXHPvWTOsXVqPgKgqy/3aAuIYHbb34PxPrQWaDkov23mCpqJs6NlSRh+dph649hd e+8MWiREWOuaVmDH4IiVTzViJCfMWPn0vRaCHcVLhNyd71rWE+oGzmtHxpndEjfaGJ ib94XthMSGL/K9/f45oGTA0BJ+CZilG4W+CMBVhmEqpWYD7iyt+Z8znthOg9rQQtBi PwBkYAMs0fKRCgPUiACMThrOPBUCtLx+NLZhBExu8TG+DLqi3NZKaTLn2wJN+rsQJ0 /oeXzSpdaZsbKUZSOX7GNIEkw6ZnazXlfbZ/+YIHyb+weE4txyZ4HZ6DOrzJi5x33I g1n84rD80/QTA== Date: Tue, 31 Mar 2026 11:23:30 +0200 From: Frederic Weisbecker To: Qiliang Yuan Cc: peterz@infradead.org, longman@redhat.com, cgroups@vger.kernel.org, akpm@linux-foundation.org, anna-maria@linutronix.de, boqun.feng@gmail.com, bsegall@google.com, dietmar.eggemann@arm.com, hannes@cmpxchg.org, jackmanb@google.com, jiangshanlai@gmail.com, joelagnelf@nvidia.com, josh@joshtriplett.org, juri.lelli@redhat.com, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-mm@kvack.org, mathieu.desnoyers@efficios.com, mgorman@suse.de, mhocko@suse.com, mingo@kernel.org, mingo@redhat.com, neeraj.upadhyay@kernel.org, paulmck@kernel.org, qiang.zhang@linux.dev, rcu@vger.kernel.org, rostedt@goodmis.org, shuah@kernel.org, surenb@google.com, tglx@kernel.org, tj@kernel.org, urezki@gmail.com, vbabka@suse.cz, vincent.guittot@linaro.org, vschneid@redhat.com, ziy@nvidia.com Subject: Re: [PATCH 01/15] sched/isolation: Support dynamic allocation for housekeeping masks Message-ID: References: <20260325135707.GZ3738786@noisy.programming.kicks-ass.net> <20260330114348.102265-1-realwujing@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20260330114348.102265-1-realwujing@gmail.com> X-Stat-Signature: rkg6gw7h3utg9y4tme6yaitmp3dyzmus X-Rspamd-Queue-Id: 47A3740011 X-Rspam-User: X-Rspamd-Server: rspam03 X-HE-Tag: 1774949014-587680 X-HE-Meta: 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 M9ZQHa8q RFNeMRemfnT2vZrvDj5tucqujmrCCf4PWOMjcl6VR8Un7DlQEfDkDMIczibWpa13Gl4aS8ak2NWaipVQZJoFKrHKiDMyJtmp9ypGqnKV5MeOr3/c/pCbuPrlJk+DudIhBIdTAPwo+gfftMT99xavPTGnTR+7VUoOxFVQAYWMoDctHZFswHsFx5o1pzN8Ss7U3lea/dnYaz3WNK1/zqFMV910sAMHycdq1+g2s+8dLiZxG3jCg65EbvAzOn/CLpv1QqapxMYY8uQqX1KzWOggMgxLGNhJGwfHCGlJWt82EtgLqJpVyYqdAY20Ghg== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Le Mon, Mar 30, 2026 at 07:43:21PM +0800, Qiliang Yuan a écrit : 11;rgb:2e2e/3434/3636> Hi Peter, > > On Wed, Mar 25, 2026 at 02:57:07PM +0100, Peter Zijlstra wrote: > > I think I asked this a while ago; why do we have more than one mask? > > What is the actual purpose of being able to separate RCU from Timers? > > That's a fair point. For the vast majority of use cases (like NOHZ_FULL), > these masks are indeed identical and should be updated as a single unit. > > The original motivation for separation was to allow extreme fine-tuning in > HFT environments—for example, offloading RCU callbacks to keep a core > mostly clean but allowing pinned timers for specific localized > telemetry/monitoring. > > However, I acknowledge this adds significant complexity. In V13, I will > unify these into a single "Global Housekeeping Mask" by default to > simplify the configuration space, while keeping the underlying notifier > infrastructure flexible enough for future specialized needs. More precisely we only need four flags: HK_TYPE_DOMAIN_BOOT (isolcpus=) HK_TYPE_DOMAIN (cgroup v2 isolated partition + isolcpus=) HK_TYPE_KERNEL_NOISE (nohz_full=) HK_TYPE_MANAGED_IRQ (isolcpus=managed_irq) All the aliases of HK_TYPE_KERNEL_NOISE need to be renamed to HK_TYPE_KERNEL_NOISE. Thanks. -- Frederic Weisbecker SUSE Labs