Hello, On Sun, Mar 09, 2025 at 04:39:40PM +0100, Andrea Righi wrote: > > Would just using a pre-allocated cpumask to do pre-and on @cpus_allowed > > work? This won't only be used for topology support (e.g. soft partitioning > > in scx_layered and scx_mitosis may want to use multi-topology-unit spanning > > subsets) and I'm not sure assuming and optimizing for that is a good idea > > for generic API. > > We can pre-allocate two additional (per-cpu) cpumasks to do: > - cpumask_and(numa_cpus, numa_span(cpu), cpus_allowed) > - cpumask_and(llc_cpus, llc_span(cpu), cpus_allowed) > > And update/use them only when it's needed. In this way the API would be > generic without making any implicit assumption about @cpus_allowed. I'm not quite following why two masks would be necessary. The user is providing two masks and and'ing those two masks result in a single cpus_allowed mask which can then be passed down to the existing pick functions, no? Thanks. -- tejun
