On Mon, Aug 05, 2024 at 11:25:59PM +0200, Vlastimil Babka wrote: > > It's too bad we don't have a way to have a cpumask_possible_of_node(). I've > > looked into the guts of numa but that doesn't look easy to do. > > That was my impression as well. Maybe not even possible because exact cpu > ids might not be pre-determined like this? Probably. > > > Or there could be kthread_set_preferred_node()... ? > > Possible instead of the callback idea suggested above? > kthreads_hotplug_update() could check if this is set and construct the mask > accordingly. Or even better, callers of kthread_create_on_node() with actual node passed (!NUMA_NO_NODE) can be preferrably affined to the corresponding node by default unless told otherwise (that is unless kthread_bind() or kthread_set_preferred_affinity() has been called before the first wake up, and that includes kthread_create_on_cpu()). There are a few callers concerned: kswapd, kcompactd, some drivers: drivers/block/mtip32xx/mtip32xx.c, drivers/firmware/stratix10-svc.c, kernel/dma/map_benchmark.c, net/sunrpc/svc.c After all kthread_create_on_cpu() affines to the corresponding CPU. So it sounds natural that kthread_create_on_node() affines to the corresponding node. And then it's handled on hotplug just as a special case of preferred affinity. Or is there something that wouldn't make that work? Thanks. > > > Thanks. > > > >> > >> > Thanks. > >> >
