Commit 272d51af authored by Eelco Chaudron's avatar Eelco Chaudron Committed by Alexei Starovoitov
Browse files

libbpf: Add API to consume the perf ring buffer content 



This new API, perf_buffer__consume, can be used as follows:

- When you have a perf ring where wakeup_events is higher than 1,
  and you have remaining data in the rings you would like to pull
  out on exit (or maybe based on a timeout).

- For low latency cases where you burn a CPU that constantly polls
  the queues.

Signed-off-by: default avatarEelco Chaudron <echaudro@redhat.com>
Signed-off-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
Acked-by: default avatarAndrii Nakryiko <andriin@fb.com>
Link: https://lore.kernel.org/bpf/159048487929.89441.7465713173442594608.stgit@ebuild


Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
parent 2b983b40

tools/lib/bpf/libbpf.c

+19 −0
Original line number Diff line number Diff line
@@ -8456,6 +8456,25 @@ int perf_buffer__poll(struct perf_buffer *pb, int timeout_ms) 
	return cnt < 0 ? -errno : cnt;

}



int perf_buffer__consume(struct perf_buffer *pb)

{

	int i, err;



	for (i = 0; i < pb->cpu_cnt; i++) {

		struct perf_cpu_buf *cpu_buf = pb->cpu_bufs[i];



		if (!cpu_buf)

			continue;



		err = perf_buffer__process_records(pb, cpu_buf);

		if (err) {

			pr_warn("error while processing records: %d\n", err);

			return err;

		}

	}

	return 0;

}



struct bpf_prog_info_array_desc {

	int	array_offset;	/* e.g. offset of jited_prog_insns */

	int	count_offset;	/* e.g. offset of jited_prog_len */

tools/lib/bpf/libbpf.h

+1 −0
Original line number Diff line number Diff line
@@ -533,6 +533,7 @@ perf_buffer__new_raw(int map_fd, size_t page_cnt, 


LIBBPF_API void perf_buffer__free(struct perf_buffer *pb);

LIBBPF_API int perf_buffer__poll(struct perf_buffer *pb, int timeout_ms);

LIBBPF_API int perf_buffer__consume(struct perf_buffer *pb);



typedef enum bpf_perf_event_ret

	(*bpf_perf_event_print_t)(struct perf_event_header *hdr,

tools/lib/bpf/libbpf.map

+1 −0
Original line number Diff line number Diff line
@@ -262,4 +262,5 @@ LIBBPF_0.0.9 { 
		bpf_link_get_fd_by_id;

		bpf_link_get_next_id;

		bpf_program__attach_iter;

		perf_buffer__consume;

} LIBBPF_0.0.8;

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