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ARM64. Hopefully I can post them to the >> mailing list to ease the discussion before the conference. > FWIW, from an s390 perspective we have been relying on that preempt_disable() > and preempt_enable() pairs for this_cpu*() ops are optimized away at compile > time for PREEMPT_NONE and PREEMPT_VOLUNTARY. Which is what all distributions > did, until now. > > With 7dadeaa6e851 ("sched: Further restrict the preemption modes") this is not > the case anymore. So the overhead will be there for every "up-to-date" > architecture except x86. I've been looking at some ways how to get rid of this > extra overhead for s390. E.g. we have an "access register mode", which can be > sort of compared to the x86 segment register approach, but switching the CPU > to this mode and back is more expensive than the preempt_disable() and > preempt_enable() pairs. > > To make the long story short: I'm very interested in your approch from an s390 > perspective (aka "other non-x86 architectures"). Hi Heiko, I just posted the RFC patches to the mailing list and cc'ed you. I separated the patches into arch-independent part and arch-dependent part, hopefully it makes your life easier. Please feel free to do your experiment for S390. Thanks, Yang