How do I attach bpf programs to perf events?

[Jun10ng]

Hi masters,

I want to pprof my prog by ebpf, so I need to call the interface bpf_program__attach_perf_event that I found on libbpf.

But cilium/ebpf seems not to implement the interface.

Is it that I did not find this method? Or is there another way to achieve my goal?

[florianl]

Hi @Jun10ng

In general ebpf and perf are two very different subsystem of the Linux Kernel. And as far as I can tell, libbpf only provides a very limited part of the perf subsystem to use with ebpf.

If you check out github.com/cilium/ebpf/link you will notice, the package link make use of perf elements for its use in Tracepoints and Kprobes. This approaches are event based. So your eBPF program will only be triggered if the tracepoint or kprobe is used.

A different part of the perf subsystem is based on sampling. And I think you might look for a solution in this space. Implementing a more wider spectrum of the perf Kernel subsystem in Go is quite complex. But there are packages like github.com/hodgesds/perf-utils and github.com/acln0/perf that are doing a great job. After setting up the desired perf event for the sampling, you can just use the returned FD and attach the eBPF program to it via
unix.IoctlSetInt(event.FD(), unix.PERF_EVENT_IOC_SET_BPF, prog.FD()).

Here I'm providing a minimal example of setting up a sample based profiling.