perf symbols: Synthesize anonymous mmap events

PATCH In review Anton Blanchard 2 participants 2 messages Aug 29, 2011 – Aug 30, 2011 perf events

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Anton Blanchard

author

2011-08-29 23:15 UTC #0 lore raw

PATCH 1/1 perf symbols: Synthesize anonymous mmap events

perf_event__synthesize_mmap_events does not create anonymous mmap events even though the kernel does. As a result an already running application with dynamically created code will not get profiled - all samples end up in the unknown bucket.

This patch skips any entries with '[' in the name to avoid adding events for special regions (eg the vsyscall page). All other executable mmaps are assumed to be anonymous and an event is synthesized.

Signed-off-by Anton Blanchard <[email protected]>

---

tools/perf/util/event.c +5 -0

index 3c1b8a6..437f8ca 100644
@@ -169,12 +169,17 @@ static int perf_event__synthesize_mmap_events(union perf_event *event,
 			continue;
 		pbf += n + 3;
 		if (*pbf == 'x') { /* vm_exec */
+			char anonstr[] = "//anon\n";
 			char *execname = strchr(bf, '/');
 
 			/* Catch VDSO */
 			if (execname == NULL)
 				execname = strstr(bf, "[vdso]");
 
+			/* Catch anonymous mmaps */
+			if ((execname == NULL) && !strstr(bf, "["))
+				execname = anonstr;
+
 			if (execname == NULL)
 				continue;

Pekka Enberg

Acked-by on v1 1/1

2011-08-30 19:11 UTC #1 lore raw

Quoted 11 lines · Anton Blanchard

perf_event__synthesize_mmap_events does not create anonymous mmap events even though the kernel does. As a result an already running application with dynamically created code will not get profiled - all samples end up in the unknown bucket.
This patch skips any entries with '[' in the name to avoid adding events for special regions (eg the vsyscall page). All other executable mmaps are assumed to be anonymous and an event is synthesized.
Signed-off-by Anton Blanchard <[email protected]>

Acked-by Pekka Enberg <[email protected]>