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

[Pavel Begunkov]

On 12/15/21 17:33, sdf@xxxxxxxxxx wrote:
> On 12/15, Pavel Begunkov wrote:
> > On 12/15/21 16:51, sdf@xxxxxxxxxx wrote:
> > > On 12/15, Pavel Begunkov wrote:
> > > > � /* Wrappers for __cgroup_bpf_run_filter_skb() guarded by cgroup_bpf_enabled. */
> > > > � #define BPF_CGROUP_RUN_PROG_INET_INGRESS(sk, skb)����������������� \
> > > > � ({����������������������������������������� \
> > > > ����� int __ret = 0;��������������������������������� \
> > > > -��� if (cgroup_bpf_enabled(CGROUP_INET_INGRESS))������������� \
> > > > +��� if (cgroup_bpf_enabled(CGROUP_INET_INGRESS) && sk &&������������� \
> > > > +������� CGROUP_BPF_TYPE_ENABLED((sk), CGROUP_INET_INGRESS))���������� \
> > >
> > > Why not add this __cgroup_bpf_run_filter_skb check to
> > > __cgroup_bpf_run_filter_skb? Result of sock_cgroup_ptr() is already there
> > > and you can use it. Maybe move the things around if you want
> > > it to happen earlier.
>
> > For inlining. Just wanted to get it done right, otherwise I'll likely be
> > returning to it back in a few months complaining that I see measurable
> > overhead from the function call :)
>
> Do you expect that direct call to bring any visible overhead?
> Would be nice to compare that inlined case vs
> __cgroup_bpf_prog_array_is_empty inside of __cgroup_bpf_run_filter_skb
> while you're at it (plus move offset initialization down?).

Sorry but that would be waste of time. I naively hope it will be visible
with net at some moment (if not already), that's how it was with io_uring,
that's what I see in the block layer. And in anyway, if just one inlined
won't make a difference, then 10 will.

--
Pavel Begunkov