Re: [PATCH v3] cgroup/bpf: fast path skb BPF filtering

[Pavel Begunkov]

On 1/24/22 18:25, Stanislav Fomichev wrote:
> On Mon, Jan 24, 2022 at 7:49 AM Pavel Begunkov <asml.silence@xxxxxxxxx> wrote:
> > On 12/16/21 18:24, Stanislav Fomichev wrote:
> > > On Thu, Dec 16, 2021 at 10:14 AM Martin KaFai Lau <kafai@xxxxxx> wrote:
> > > > On Thu, Dec 16, 2021 at 01:21:26PM +0000, Pavel Begunkov wrote:
> > > > > On 12/15/21 22:07, Stanislav Fomichev wrote:
> > > > > > > I'm skeptical I'll be able to measure inlining one function,
> > > > > > > variability between boots/runs is usually greater and would hide it.
> > > > > >
> > > > > > Right, that's why I suggested to mirror what we do in set/getsockopt
> > > > > > instead of the new extra CGROUP_BPF_TYPE_ENABLED. But I'll leave it up
> > > > > > to you, Martin and the rest.
> > > > I also suggested to try to stay with one way for fullsock context in v2
> > > > but it is for code readability reason.
> > > >
> > > > How about calling CGROUP_BPF_TYPE_ENABLED() just next to cgroup_bpf_enabled()
> > > > in BPF_CGROUP_RUN_PROG_*SOCKOPT_*() instead ?
> > >
> > > SG!
> > >
> > > > It is because both cgroup_bpf_enabled() and CGROUP_BPF_TYPE_ENABLED()
> > > > want to check if there is bpf to run before proceeding everything else
> > > > and then I don't need to jump to the non-inline function itself to see
> > > > if there is other prog array empty check.
> > > >
> > > > Stan, do you have concern on an extra inlined sock_cgroup_ptr()
> > > > when there is bpf prog to run for set/getsockopt()?  I think
> > > > it should be mostly noise from looking at
> > > > __cgroup_bpf_run_filter_*sockopt()?
> > >
> > > Yeah, my concern is also mostly about readability/consistency. Either
> > > __cgroup_bpf_prog_array_is_empty everywhere or this new
> > > CGROUP_BPF_TYPE_ENABLED everywhere. I'm slightly leaning towards
> > > __cgroup_bpf_prog_array_is_empty because I don't believe direct
> > > function calls add any visible overhead and macros are ugly :-) But
> > > either way is fine as long as it looks consistent.
> >
> > Martin, Stanislav, do you think it's good to go? Any other concerns?
> > It feels it might end with bikeshedding and would be great to finally
> > get it done, especially since I find the issue to be pretty simple.
>
> I'll leave it up to the bpf maintainers/reviewers. Personally, I'd
> still prefer a respin with a consistent
> __cgroup_bpf_prog_array_is_empty or CGROUP_BPF_TYPE_ENABLED everywhere
> (shouldn't be a lot of effort?)

I can make CGROUP_BPF_TYPE_ENABLED() used everywhere, np.

I'll leave out unification with cgroup_bpf_enabled() as don't
really understand the fullsock dancing in
BPF_CGROUP_RUN_PROG_INET_EGRESS(). Any idea whether it's needed
and/or how to shove it out of inlined checks?

--
Pavel Begunkov