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b=ivqQcR2dZy35lYabU0BBXKzj+XDUwkDqyBwMEtaqaUyM3k21UuHgbvPrCu7ZusHVr ytprZXkVMFgMLhdj/VGJQHTMTI2piW0GLLVtC7zskwte6Gqc6C/CnEF7tuvFbzhrBg xrQ1g0uibn4nPEwbmuA1ac4GkOIoIRESGZV7ygQIMR+2IGaHmvf4XdPXA9gbXaPbIn mwoAaZFuHHvrcSHkVwbeuDpNtuJe4fKFqLNzVJZnheiBaNnYd+kgSH6jIbHUfvZ9Jc HEN41kioO7XOqaqChUh0oT+h8cM3NYpOzyF82zaFJrB6WAlTFd+2ek6RAWvTp38BtX 3Kykii1gy2Ebw== Date: Mon, 30 Mar 2026 08:34:56 -1000 From: Tejun Heo 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, frederic@kernel.org, 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, urezki@gmail.com, vbabka@suse.cz, vincent.guittot@linaro.org, vschneid@redhat.com, ziy@nvidia.com Subject: Re: [PATCH 13/15] sched/isolation: Implement sysfs interface for dynamic housekeeping Message-ID: References: <20260325140432.GE3738786@noisy.programming.kicks-ass.net> <20260330114620.104027-1-realwujing@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260330114620.104027-1-realwujing@gmail.com> X-Rspamd-Queue-Id: BBB6D180008 X-Stat-Signature: 859ybh3r6agq1yax9ggnpjyi469afqkw X-Rspam-User: X-Rspamd-Server: rspam08 X-HE-Tag: 1774895698-307222 X-HE-Meta: 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 22X29VOn jojUSvBPnq5jNhszgXdQ1y6HU62B8n8mgdXSX1WalgzD1nMdWnMW8flhDVsKPf+4dRMFHwPVsxjFo2gm2cLS3GpNClPo9EQJHGd3/U87Pcv+S6hzUARq/99EVq9bFg6OHgtWgHjmcJXF/ACnjKVnPa1WqbppiMK8hmaAgTxOop2UPpvMeVveSQqsazIYhwo5AB2HbgJhkyXyfvCG/KPtGig1Z9i26F92fOU0doM37B33j1jT8hbLs0nw2/HiEozHnykFApJhLk9DSnr4a4YhRtldYdtjLiKclNXad Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: cc'ing Waiman. On Mon, Mar 30, 2026 at 07:46:20PM +0800, Qiliang Yuan wrote: > On Wed, Mar 25, 2026 at 03:04:32PM +0100, Peter Zijlstra wrote: > > Why? What was wrong with cpusets? > > This is the central point of the architecture. The distinction I was > trying to address is: > > 1. Task Isolation (Current CPUSets): > The `cpuset` subsystem (especially `cpuset.cpus.partition = isolated`) > is excellent at managing task placement and load balancing. It > ensures no user tasks are pushed to isolated CPUs. > > 2. Kernel Overhead Isolation (Housekeeping): > Currently, `cpusets` do not manage kernel-internal overhead like RCU > callbacks, timers, or unbound workqueues. These are managed by the > global `housekeeping_cpumask`, which is settled at boot via > `isolcpus`/`nohz_full` and is static. > > DHEI fills this second gap by making the housekeeping mask dynamic. > However, I agree that a parallel sysfs interface is redundant. > > In V13, I will move the control interface to `cpuset`. The root cpuset > will serve as the primary interface, allowing changes in the cpuset > partition state to automatically trigger the migration of kernel > housekeeping overhead. This achieves "Full Dynamic Isolation" (both tasks > and kernel overhead) through a single, unified interface. Please discuss with Frederic and Waiman first because they have been working towards making cpuset to cover what cpuisol does. I don't think we want two separate mechanisms for the same thing and don't see why this would need to be its own thing when it has to be coupled with task isolation anyway. Thanks. -- tejun