Commit 57cbd56e authored Jun 06, 2025 by Ian Rogers Committed by Namhyung Kim Jun 25, 2025

perf header: Allow tracing of attr events



In pipe mode attr events capture the perf_event_attr. Allow their
dumping as they normally start the file.

Before:
```
$ perf record -o - -a sleep 1 | perf script -D -i -
. ... raw event: size 272 bytes
.  0000:  40 00 00 00 00 00 10 01 00 00 00 00 88 00 00 00  @...............
.  0010:  00 00 00 00 00 00 00 00 a0 0f 00 00 00 00 00 00  ................
.  0020:  87 01 01 00 00 00 00 00 14 00 00 00 00 00 00 00  ................
.  0030:  01 84 05 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
.  0040:  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
.  0050:  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
.  0060:  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
.  0070:  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
.  0080:  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
.  0090:  91 08 00 00 00 00 00 00 92 08 00 00 00 00 00 00  ................
.  00a0:  93 08 00 00 00 00 00 00 94 08 00 00 00 00 00 00  ................
.  00b0:  95 08 00 00 00 00 00 00 96 08 00 00 00 00 00 00  ................
.  00c0:  97 08 00 00 00 00 00 00 98 08 00 00 00 00 00 00  ................
.  00d0:  99 08 00 00 00 00 00 00 9a 08 00 00 00 00 00 00  ................
.  00e0:  9b 08 00 00 00 00 00 00 9c 08 00 00 00 00 00 00  ................
.  00f0:  9d 08 00 00 00 00 00 00 9e 08 00 00 00 00 00 00  ................
.  0100:  9f 08 00 00 00 00 00 00 a0 08 00 00 00 00 00 00  ................

-1 -1 0 [0x110]: PERF_RECORD_ATTR
0x110@pipe [0x110]: event: 64
...
```

After:
```
$ perf record -o - -a sleep 1 | perf script -D -i -
0@pipe [0x110]: event: 64
.
. ... raw event: size 272 bytes
.  0000:  40 00 00 00 00 00 10 01 00 00 00 00 88 00 00 00  @...............
.  0010:  00 00 00 00 00 00 00 00 a0 0f 00 00 00 00 00 00  ................
.  0020:  87 01 01 00 00 00 00 00 14 00 00 00 00 00 00 00  ................
.  0030:  01 84 05 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
.  0040:  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
.  0050:  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
.  0060:  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
.  0070:  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
.  0080:  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
.  0090:  5c 08 00 00 00 00 00 00 5d 08 00 00 00 00 00 00  \.......].......
.  00a0:  5e 08 00 00 00 00 00 00 5f 08 00 00 00 00 00 00  ^......._.......
.  00b0:  60 08 00 00 00 00 00 00 61 08 00 00 00 00 00 00  `.......a.......
.  00c0:  62 08 00 00 00 00 00 00 63 08 00 00 00 00 00 00  b.......c.......
.  00d0:  64 08 00 00 00 00 00 00 65 08 00 00 00 00 00 00  d.......e.......
.  00e0:  66 08 00 00 00 00 00 00 67 08 00 00 00 00 00 00  f.......g.......
.  00f0:  68 08 00 00 00 00 00 00 69 08 00 00 00 00 00 00  h.......i.......
.  0100:  6a 08 00 00 00 00 00 00 6b 08 00 00 00 00 00 00  j.......k.......

-1 -1 0 [0x110]: PERF_RECORD_ATTR, type = 0 (PERF_TYPE_HARDWARE), size = 136, config = 0 (PERF_COUNT_HW_CPU_CYCLES), { sample_period, sample_freq } = 4000, sample_type = IP|TID|TIME|CPU|PERIOD|IDENTIFIER, read_format = ID|LOST, disabled = 1, freq = 1, precise_ip = 3, sample_id_all = 1
0x110@pipe [0x110]: event: 64
...
```

Signed-off-by: Ian Rogers <irogers@google.com>
Link: https://lore.kernel.org/r/20250617223356.2752099-4-irogers@google.com


Signed-off-by: Namhyung Kim <namhyung@kernel.org>

parent 61051f9a

tools/perf/util/header.c

+8 −0

Original line number	Diff line number	Diff line
		@@ -4399,6 +4399,11 @@ size_t perf_event__fprintf_event_update(union perf_event event, FILE fp)
		return ret;
		}

		size_t perf_event__fprintf_attr(union perf_event event, FILE fp)
		{
		return perf_event_attr__fprintf(fp, &event->attr.attr, __desc_attr__fprintf, NULL);
		}

		int perf_event__process_attr(const struct perf_tool *tool __maybe_unused,
		union perf_event *event,
		struct evlist **pevlist)
		@@ -4408,6 +4413,9 @@ int perf_event__process_attr(const struct perf_tool *tool __maybe_unused,
		struct evsel *evsel;
		struct evlist evlist = pevlist;

		if (dump_trace)
		perf_event__fprintf_attr(event, stdout);

		if (evlist == NULL) {
		*pevlist = evlist = evlist__new();
		if (evlist == NULL)

tools/perf/util/header.h

+1 −0

Original line number	Diff line number	Diff line
		@@ -175,6 +175,7 @@ int perf_event__process_attr(const struct perf_tool tool, union perf_event eve
		int perf_event__process_event_update(const struct perf_tool *tool,
		union perf_event *event,
		struct evlist **pevlist);
		size_t perf_event__fprintf_attr(union perf_event event, FILE fp);
		size_t perf_event__fprintf_event_update(union perf_event event, FILE fp);
		#ifdef HAVE_LIBTRACEEVENT
		int perf_event__process_tracing_data(struct perf_session *session,