On 07/10/2017 10:53 AM, Jesper Dangaard Brouer wrote: > On Fri, 07 Jul 2017 10:37:59 -0700 > John Fastabend <john.fastab...@gmail.com> wrote: > >> diff --git a/kernel/bpf/devmap.c b/kernel/bpf/devmap.c >> index 36dc13de..656e334 100644 >> --- a/kernel/bpf/devmap.c >> +++ b/kernel/bpf/devmap.c > [...] >> >> +void __dev_map_insert_ctx(struct bpf_map *map, u32 key) >> +{ >> + struct bpf_dtab *dtab = container_of(map, struct bpf_dtab, map); >> + unsigned long *bitmap = this_cpu_ptr(dtab->flush_needed); >> + >> + set_bit(key, bitmap); >> +} > > I don't like that this adds an atomic op (set_bit) per packet on a fast-path. > It shows up on a perf top #6 with xdp_redirect_map. >
Its a per cpu bitmap so __set_bit() should be fine here. Thanks, John