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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 , Waiman Long , 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 29/33] sched/arm64: Move fallback task cpumask to HK_TYPE_DOMAIN Message-ID: References: <20260125224541.50226-1-frederic@kernel.org> <20260125224541.50226-30-frederic@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260125224541.50226-30-frederic@kernel.org> X-Stat-Signature: xhcwwrf18myeg5546otojrd65s7fc11x X-Rspam-User: X-Rspamd-Server: rspam08 X-Rspamd-Queue-Id: 596781C000D X-HE-Tag: 1769435536-467048 X-HE-Meta: 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 FWLm5B15 KJIZAXpPaCpe3jvdN+8U5fIcSektB3HD9fhn4mEIH6IW5YjwwxAfHoQ9u5eVOEoWk6KeOiGT7UZtRJmZJVptwvPxVJucEtAKGdVU40XTuCjPkJMPGaIY4pIZMYWLovuRfS1zUdEI2w8IfwRB7yfehmPRoqb+dUPYl2D0g0RNsOwBlJthK176c6ZBVHKIH14yqJhJk/wXE1Vnp8hhj8PCoYkSezEAvHJbaPQ7Wl3m51YIGUZXc85QaSDmwY7QOC7dl46m5oM/5CCCTzqlrCeD8DYsAyI6gRSer09sE1fPBDKdCtmUCxNNLUVIGD2H6/iZynvW2OJc3zpf6yowLib+soDTWVw== 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: On Sun, Jan 25, 2026 at 11:45:36PM +0100, Frederic Weisbecker wrote: > When none of the allowed CPUs of a task are online, it gets migrated > to the fallback cpumask which is all the non nohz_full CPUs. > > However just like nohz_full CPUs, domain isolated CPUs don't want to be > disturbed by tasks that have lost their CPU affinities. > > And since nohz_full rely on domain isolation to work correctly, the > housekeeping mask of domain isolated CPUs should always be a subset of > the housekeeping mask of nohz_full CPUs (there can be CPUs that are > domain isolated but not nohz_full, OTOH there shouldn't be nohz_full > CPUs that are not domain isolated): > > HK_TYPE_DOMAIN & HK_TYPE_KERNEL_NOISE == HK_TYPE_DOMAIN > > Therefore use HK_TYPE_DOMAIN as the appropriate fallback target for > tasks. Note that cpuset isolated partitions are not supported on those > systems and may result in undefined behaviour. > > Signed-off-by: Frederic Weisbecker > Reviewed-by: Waiman Long > --- > Documentation/arch/arm64/asymmetric-32bit.rst | 12 ++++++++---- > arch/arm64/kernel/cpufeature.c | 6 +++--- > 2 files changed, 11 insertions(+), 7 deletions(-) Thanks, Frederic, this looks much better to me. I also chucked my old tests at it and it looked good, so: Acked-by: Will Deacon Tested-by: Will Deacon Will