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([2601:188:c180:4250:ecbe:130d:668d:951d]) by smtp.gmail.com with ESMTPSA id 6a1803df08f44-720ad897a98sm13837816d6.26.2025.09.02.08.48.16 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 02 Sep 2025 08:48:17 -0700 (PDT) From: Waiman Long X-Google-Original-From: Waiman Long Message-ID: <152b067c-1fa3-4b73-98f3-7e0a0c87e388@redhat.com> Date: Tue, 2 Sep 2025 11:48:16 -0400 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 19/33] sched/isolation: Remove HK_TYPE_TICK test from cpu_is_isolated() To: Frederic Weisbecker , LKML Cc: Ingo Molnar , Marco Crivellari , Michal Hocko , Peter Zijlstra , Tejun Heo , Thomas Gleixner , Vlastimil Babka References: <20250829154814.47015-1-frederic@kernel.org> <20250829154814.47015-20-frederic@kernel.org> Content-Language: en-US In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 9/2/25 10:28 AM, Waiman Long wrote: > > On 8/29/25 11:48 AM, Frederic Weisbecker wrote: >> It doesn't make sense to use nohz_full without also isolating the >> related CPUs from the domain topology, either through the use of >> isolcpus= or cpuset isolated partitions. >> >> And now HK_TYPE_DOMAIN includes all kinds of domain isolated CPUs. >> >> This means that HK_TYPE_KERNEL_NOISE (of which HK_TYPE_TICK is only an >> alias) is always a superset of HK_TYPE_DOMAIN. > > That may not be true. Users can still set "isolcpus=" and "nohz_full=" > with disjoint set of CPUs whether cpuset is used for additional > isolated CPUs or not. Instead of "is always a superset", I would prefer to use "should always be a superset" as it is a recommendation but users can still violate it. Cheers, Longman