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With the RV nrp monitor > > enabled, 300 runs of "perf bench sched messaging -g 20 -l 100" produced: > > > >   rv: monitor nrp does not allow event schedule_entry_preempt on state > > any_thread_running > > > > Applying the following on top fixed the ordering, the same 300-run test then > > completed without an RV violation. If it makes sense, could you fold this > > change into v4? > > > > Thanks, > > -Andrea > > thanks for looking into this. Is this change required for anything else besides > fixing the nrp monitor after changing the order with need_resched? No, I was mainly trying to help get this fix upstream: a sched_ext kselftest I'm working on hits that issue and I'm holding off on submitting the test until the fix lands. Moving sched_entry was only my attempt to address the nrp warning I saw while testing the fix. > > I believe this would break the sts monitor which expects sched_entry before > disabling interrupts. > > Both monitors could be adapted to either case, but if your change is just for > the sake of nrp, I think it's easier to just allow this race, since nrp is > already allowing the race with interrupts. > I haven't tested yet, but something like allowing a sched_entry_preempt without > need_resched set but provided it's going to be set before sched_exit would > probably do (it'd allow also independent need_resched there, but those will then > need their own preemption too). > > I'd say if you don't need to move sched_entry for other reasons we can wait to > apply this change until I see what's better for the models. That makes sense, we can ignore the sched_entry change for now. With that, Sechang's fix looks good to me. Reviewed-by: Andrea Righi Thanks, -Andrea