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Tue, 31 Mar 2026 14:38:28 +0000 (UTC) Received: from [10.22.80.26] (unknown [10.22.80.26]) by mx-prod-int-01.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id 1756030001A2; Tue, 31 Mar 2026 14:38:20 +0000 (UTC) Message-ID: Date: Tue, 31 Mar 2026 10:38:20 -0400 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 13/15] sched/isolation: Implement sysfs interface for dynamic housekeeping To: Qiliang Yuan , peterz@infradead.org Cc: 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, tj@kernel.org, urezki@gmail.com, vbabka@suse.cz, vincent.guittot@linaro.org, vschneid@redhat.com, ziy@nvidia.com References: <20260325140432.GE3738786@noisy.programming.kicks-ass.net> <20260330114620.104027-1-realwujing@gmail.com> From: Waiman Long In-Reply-To: <20260330114620.104027-1-realwujing@gmail.com> X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.4 X-Mimecast-MFC-PROC-ID: t3dd0U10IZbmekC6KLov1qWdvBds3hAGWGyoCCYibCE_1774967909 X-Mimecast-Originator: redhat.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Rspamd-Queue-Id: 22E92100004 X-Stat-Signature: a35tfrwxutstj4cpudrup7ze9kbdi1n8 X-Rspam-User: X-Rspamd-Server: rspam04 X-HE-Tag: 1774967916-956420 X-HE-Meta: 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 mmC1woDW jtEGd+cJzb7NBnQlvSAUUH0qQRWb43VG1XGS/RFI+VGBpCEMOTTNsnBdFALrGDdKjuyRFyeqyMS9O8H2AMuOCbmtgJ0OaeID4YlIbgpjCmrnfHRd2Bq4dICBLz0wlJ/dreIOs2ZE0H9spxN3H8Gizi1HmFPy0LikswO+4BNunzSPCdOVYiwyiZdo8Gfcqep2aFsRJBKwVLaA6uCivvGby2i2wCuL6lDeBOm4zpSGyRKPjPa92dkUwzojQvfHXckVmwtvMJ0FBh4Cr820FoKRfZYjogtWIwTbfM2QtPOowPFrk+TNZPkujrR4BG6NQ4yoItSzgtl5Jmrne0BYD3R5kFGp9NW1zzL8Wy6ecl9Ans3ANfs2+j/P4psw9bgjMftg1lzPQgpuU/a6+XuA= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 3/30/26 7:46 AM, 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. My plan is to extend the cpuset isolated partition mechanism to isolate other kernel noise currently covered by the nohz_full and manged_irq boot command line. That will makes the HK_TYPE_KERNEL_NOISE cpumask modifiable at run time. It is not a direct modification of the HK cpumasks as advocated by this patch series but an indirect one via the creation of the appropriate isolated cpuset partitions. Cheers, Longman