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If @p is not on CPU0, it can't run on > * CPU 0. Queue on whichever CPU it's currently only. > */ > if (scx_bpf_task_cpu(p) != 0) { > stat_inc(0); /* count local queueing */ > scx_bpf_dsq_insert(p, SCX_DSQ_LOCAL, SCX_SLICE_DFL, 0); > return; > } > > stat_inc(1); /* count cpu0 queueing */ > scx_bpf_dsq_insert(p, DSQ_CPU0, SCX_SLICE_DFL, enq_flags); > } > > This should be safe against migration disabled tasks and so on. Looks good. > > > > + stat_inc(0); /* count local queueing */ > > > + scx_bpf_dsq_insert(p, SCX_DSQ_LOCAL, SCX_SLICE_DFL, 0); > > > > And this is why I was suggesting to automatically fallback to the new > > global default time slice internally. In this case do we want to preserve > > the old 20ms default or automatically switch to the new one? > > Maybe SCX_SLICE_DFL can become runtime loaded const volatile but anyone > who's using it is just saying "I don't care". As long as it's not something > that breaks the system left and right, does it matter what exact value it > is? I agree that if a scheduler uses SCX_SLICE_DFL it shouldn't care too much about the exact value. My concern was more about those schedulers that are quite paranoid about latency and even if something isn't handled properly (directly dispatching to a wrong CPU, a task being rescheduled internally, etc.), we'd still have a guarantee that a task's time slice can't exceed a known upper bound. But this could be managed by being able to set a default time slice (somehow) and it can be addressed separately. So yeah, in this case the exact value of SCX_SLICE_DFL doesn't really matter probably. -Andrea