On Tue, Dec 14, 2021 at 10:00 AM Pavel Begunkov <asml.silence@xxxxxxxxx> wrote: > > On 12/14/21 17:54, sdf@xxxxxxxxxx wrote: > > On 12/11, Pavel Begunkov wrote: > >> On 12/11/21 01:56, Martin KaFai Lau wrote: > >> > On Sat, Dec 11, 2021 at 01:15:05AM +0000, Pavel Begunkov wrote: > >> > > That was the first idea, but it's still heavier than I'd wish. 0.3%-0.7% > >> > > in profiles, something similar in reqs/s. rcu_read_lock/unlock() pair is > >> > > cheap but anyway adds 2 barrier()s, and with bitmasks we can inline > >> > > the check. > >> > It sounds like there is opportunity to optimize > >> > __cgroup_bpf_prog_array_is_empty(). > >> > > >> > How about using rcu_access_pointer(), testing with &empty_prog_array.hdr, > >> > and then inline it? The cgroup prog array cannot be all > >> > dummy_bpf_prog.prog. If that could be the case, it should be replaced > >> > with &empty_prog_array.hdr earlier, so please check. > > > >> I'd need to expose and export empty_prog_array, but that should do. > >> Will try it out, thanks > > > > Note that we already use __cgroup_bpf_prog_array_is_empty in > > __cgroup_bpf_run_filter_setsockopt/__cgroup_bpf_run_filter_getsockopt > > for exactly the same purpose. If you happen to optimize it, pls > > update these places as well. > > Just like it's already done in the patch? Or maybe you mean something else? Ah, you already did it, looks good! I didn't scroll all the way to the bottom and got distracted by Martin's comment about __cgroup_bpf_prog_array_is_empty :-[
