doc: explain how to use perf with skb programs
explain how to use perf with skb programs
@@ -521,6 +521,8 @@ Return: 0 on success
A method of a BPF_PERF_OUTPUT table, for submitting custom event data to user space. See the BPF_PERF_OUTPUT entry. (This ultimately calls bpf_perf_event_output().)
+The ```ctx``` parameter is provided in [kprobes](#1-kprobes) or [kretprobes](#2-kretprobes). For ```SCHED_CLS``` or ```SOCKET_FILTER``` programs, the ```struct __sk_buff *skb``` must be used instead.
+
Examples in situ:
[search /examples](https://github.com/iovisor/bcc/search?q=perf_submit+path%3Aexamples&type=Code),
[search /tools](https://github.com/iovisor/bcc/search?q=perf_submit+path%3Atools&type=Code)
