Hi Tejun, On Thu, Mar 06, 2025 at 08:34:15AM -1000, Tejun Heo wrote: > Hello, > > On Thu, Mar 06, 2025 at 07:18:03PM +0100, Andrea Righi wrote: > > To implement this, introduce a new helper kfunc scx_bpf_select_cpu_pref() > > that allows to specify a cpumask of preferred CPUs: > > > > s32 scx_bpf_select_cpu_pref(struct task_struct *p, > > const struct cpumask *preferred_cpus, > > s32 prev_cpu, u64 wake_flags, u64 flags); > > > > Moreover, introduce the new idle flag %SCX_PICK_IDLE_IN_PREF that can be > > used to enforce selection strictly within the preferred domain. > > Would something like scx_bpf_select_cpu_and() work which is only allowed > pick in the intersection (ie. always SCX_PICK_IDLE_IN_PREF). I'm not sure > how much more beneficial a built-in two-level mechanism is especially given > that it wouldn't be too uncommon to need multi-level pick - e.g. within l3 > then within numa node and so on. Just to make sure I understand, you mean provide two separate kfuncs: scx_bpf_select_cpu_and() and scx_bpf_select_cpu_pref(), instead of introducing the flag? Thanks, -Andrea
