Re: PF_PACKET RPS like using bpf

[Yonghong Song <yonghong.song@linux.dev>]

On 3/15/24 11:30 AM, Stanislav Fomichev wrote:
> On 03/15, Alexandre Cassen wrote:
>>
>> On 15/03/2024 18:31, Stanislav Fomichev wrote:
>>> On 03/14, Alexandre Cassen wrote:
>>>> Hello,
>>>>
>>>> While implementing a large scale L2 processing soft, there is a need for
>>>> high perf ingress handling.
>>>>
>>>> In short: using BPF socket_filter prog with a hash func over ethernet
>>>> address to distribute load across multiple PF_PACKET sockets: mainly
>>>> filtering out non related hkey packets. It simplify userland app by using
>>>> multiple PF_PACKET sockets in dedicated pthread.
>>>>
>>>> Longer discussion + quick source code illustration here:
>>>>
>>>> https://github.com/acassen/bpf-pfpacket-rps
>>>>
>>>>
>>>> My question would be related to sockmap. I tried to figure out how to
>>>> perform the same policing design using sockmap. And cant find my way around
>>>> it :/ If bpf verdict prog can get socket fd from __sk_buff then it could
>>>> drives the same hash/policing decision.
>>>>
>>>> Is it possible to get socket fd from __sk_buff from sockmap verdict prog ?
>>> Don't have an answer about sockmap, but I'd suggest you look at AF_XDP
>>> if you want the best perf out there with raw frames.
>>> IIRC, it just recently got a mode where you can redirect into multiple
>>> sockets (== consumer threads):
>>>
>>> https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next.git/commit/?id=2863d665ea41
>> thanks for replying, __sk_buff bpf mirror doesnt export struct sock as
>> present into kernel skbuff, so no options but extending.
>> AF_XDP is an option. Will extend test code with it later on.
> We do export bpf_sock in __sk_buff:
>
> 	__bpf_md_ptr(struct bpf_sock *, sk);
>
> But it has a very minimal set of 'struct sock' fields exported.

You could use bpf_core_cast() in bpf_core_read.h to cast 'struct bpf_sock' to kernel 'struct sock'.

>