Re: [PATCH bpf-next v1 1/3] bpf, sockmap: Introduce a new kfunc for sockmap

On Mon, Apr 28, 2025 at 04:16:52PM +0800, Jiayuan Chen wrote:

+bpf_sk_skb_set_redirect_cpu() +^^^^^^^^^^^^^^^^^^^^^^ +.. code-block:: c

• int bpf_sk_skb_set_redirect_cpu(struct __sk_buff *s, int redir_cpu)

+This kfunc ``bpf_sk_skb_set_redirect_cpu()`` is available to +``BPF_PROG_TYPE_SK_SKB`` BPF programs. It sets the CPU affinity, allowing the +sockmap packet redirecting process to run on the specified CPU as much as +possible, helping users reduce the interference between the sockmap redirecting +background thread and other threads.

I am wondering if it is a better idea to use BPF_MAP_TYPE_CPUMAP for redirection here instead? Like we did for bpf_redirect_map(). At least we would not need to store CPU in psock with this approach.

Thanks.