From: Eelco Chaudron <echaudro@redhat.com>
To: bpf@vger.kernel.org
Cc: davem@davemloft.net, netdev@vger.kernel.org, ast@kernel.org,
daniel@iogearbox.net, kafai@fb.com, songliubraving@fb.com,
yhs@fb.com, andriin@fb.com, toke@redhat.com
Subject: [PATCH bpf-next v2] libbpf: add API to consume the perf ring buffer content
Date: Tue, 26 May 2020 11:21:42 +0200 [thread overview]
Message-ID: <159048487929.89441.7465713173442594608.stgit@ebuild> (raw)
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: Eelco Chaudron <echaudro@redhat.com>
---
v2:
- Removed some input checks
- Support spare CPU buffers
- Moved variable "err" up
tools/lib/bpf/libbpf.c | 19 +++++++++++++++++++
tools/lib/bpf/libbpf.h | 1 +
tools/lib/bpf/libbpf.map | 1 +
3 files changed, 21 insertions(+)
diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index fa04cbe547ed..5d60de6fd818 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -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 */
diff --git a/tools/lib/bpf/libbpf.h b/tools/lib/bpf/libbpf.h
index 8ea69558f0a8..1e2e399a5f2c 100644
--- a/tools/lib/bpf/libbpf.h
+++ b/tools/lib/bpf/libbpf.h
@@ -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,
diff --git a/tools/lib/bpf/libbpf.map b/tools/lib/bpf/libbpf.map
index 0133d469d30b..381a7342ecfc 100644
--- a/tools/lib/bpf/libbpf.map
+++ b/tools/lib/bpf/libbpf.map
@@ -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;
next reply other threads:[~2020-05-26 9:21 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-26 9:21 Eelco Chaudron [this message]
2020-05-26 17:42 ` [PATCH bpf-next v2] libbpf: add API to consume the perf ring buffer content Andrii Nakryiko
2020-05-26 21:15 ` Daniel Borkmann
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