Re: [PATCH bpf-next v2 00/21] bpf: Add tracing_multi link support for bpf progs

[Jiri Olsa]

On Mon, Oct 12, 2026 at 11:40:02PM +0800, Leon Hwang wrote:
> Similar to the tracing_multi link support for kernel functions [1], add
> support for bpf progs.
> 
> With this support, I'll be able to enhance the function-graph feature of
> bpfsnoop [2]. It will trace all bpf progs, including their subprogs, to
> draw a full function call graph including bpf prog call sites.
> 
> The attachment could speed-up when there are hundreds of targets. For
> example, on high CPU core count servers, it probably runs 200 tc-bpf
> progs as Kubernetes CNI, and each tc-bpf prog might have 4 subprogs.
> Hence, there will be 1000 targets to trace for bpfsnoop's function-graph
> feature.
> 
> With tracing_multi link support for bpf progs, bpfsnoop will be able to
> attach to all targets quickly.
> 
> When attaching to 1000 targets, fentry.multi is much faster than fentry
> on a 16c16g QEMU VM on an AMD EPYC 9745 server.
> 
> ./bench tracing-multi-attach-progs
> Setting up benchmark 'tracing-multi-attach-progs'...
> tracing-multi-attach-progs: prepared 1000 identical BPF program targets
> tracing-multi-attach-progs: fentry created and attached 1000 programs/links in 338.171ms
> tracing-multi-attach-progs: fentry.multi created one program and attached one 1000-target link in 47.345ms
> tracing-multi-attach-progs: fentry.multi creation/attachment speedup is 7.14x

it's faster, but the original attachment is under 1s,
so not really a problem imo

I guess the api is better for your use case, like having
less file descriptors open ?

jirka