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charset=us-ascii Content-Disposition: inline X-Rspam-User: X-Rspamd-Queue-Id: D573B1A000C X-Rspamd-Server: rspam07 X-Stat-Signature: dkjd5bqd49u157c5ecqyhkjznei16wst X-HE-Tag: 1770828677-235750 X-HE-Meta: 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 zE3pOAik XeV3K+tsMTuDyT9PN49PRTWiSa3wtSVeBAmfsrU7xyJRIKV5b6OLtapuyDCUm38qFA7rIBECK74Vv9kF21JrEufJ/M+FPqGHg6XDVNFL2B+3tvCQgtdE3w1aMYHn6LP1WJIRylpae/xk4QUaKP2VeuZ6uE7HzbJkmkJaLsfk9kbUelXA2R6MeNOPF4+UlDejI2XyYQyRXNCQdT1Kld728/XIwn1ODtUWpunpyBr/ueKTjRAIyXfb99Q5EO7Ck8SUHIouHJF1OIkor7W6GWdriiwPNq5MfD/fXau5mDBqqCnp+C0TbAQm/Lgj0q7UKhDw0Yl9AhFJtEv6grV88bhcHgP9Eq9EnTYsq3g5qDcN/3+rJLIETzoIYT8VWD4QsKTddMaaArPumYa/ZuvA= 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 Wed, Feb 11, 2026 at 05:38:47PM +0100, Michal Hocko wrote: > On Wed 11-02-26 09:01:12, Marcelo Tosatti wrote: > > On Tue, Feb 10, 2026 at 03:01:10PM +0100, Michal Hocko wrote: > [...] > > > What about !PREEMPT_RT? We have people running isolated workloads and > > > these sorts of pcp disruptions are really unwelcome as well. They do not > > > have requirements as strong as RT workloads but the underlying > > > fundamental problem is the same. Frederic (now CCed) is working on > > > moving those pcp book keeping activities to be executed to the return to > > > the userspace which should be taking care of both RT and non-RT > > > configurations AFAICS. > > > > Michal, > > > > For !PREEMPT_RT, _if_ you select CONFIG_QPW=y, then there is a kernel > > boot option qpw=y/n, which controls whether the behaviour will be > > similar (the spinlock is taken on local_lock, similar to PREEMPT_RT). > > My bad. I've misread the config space of this. My bad, actually. Its only CONFIG_QPW on the current patchset. > > If CONFIG_QPW=n, or kernel boot option qpw=n, then only local_lock > > (and remote work via work_queue) is used. > > > > What "pcp book keeping activities" you refer to ? I don't see how > > moving certain activities that happen under SLUB or LRU spinlocks > > to happen before return to userspace changes things related > > to avoidance of CPU interruption ? > > Essentially delayed operations like pcp state flushing happens on return > to the userspace on isolated CPUs. No locking changes are required as > the work is still per-cpu. > > In other words the approach Frederic is working on is to not change the > locking of pcp delayed work but instead move that work into well defined > place - i.e. return to the userspace. > > Btw. have you measure the impact of preempt_disbale -> spinlock on hot > paths like SLUB sheeves? Nope, i have not. What is/are the standard benchmarks for SLUB/SLAB allocation ?