perf tools: Look up thread names for system wide profiling
This handles multithreaded processes with named threads when doing
system wide profiling: the comm for each thread is looked up allowing
them to be different from the thread group leader.
v2:
- fixed sizeof arg to perf_event__get_comm_tgid
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1324578603-12762-3-git-send-email-dsahern@gmail.com
Signed-off-by: David Ahern <dsahern@gmail.com>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
diff --git a/tools/perf/util/event.c b/tools/perf/util/event.c
index a578726..73ddaf0 100644
--- a/tools/perf/util/event.c
+++ b/tools/perf/util/event.c
@@ -43,37 +43,27 @@
.period = 1,
};
-static pid_t perf_event__synthesize_comm(struct perf_tool *tool,
- union perf_event *event, pid_t pid,
- int full, perf_event__handler_t process,
- struct machine *machine)
+static pid_t perf_event__get_comm_tgid(pid_t pid, char *comm, size_t len)
{
char filename[PATH_MAX];
char bf[BUFSIZ];
FILE *fp;
size_t size = 0;
- DIR *tasks;
- struct dirent dirent, *next;
- pid_t tgid = 0;
+ pid_t tgid = -1;
snprintf(filename, sizeof(filename), "/proc/%d/status", pid);
fp = fopen(filename, "r");
if (fp == NULL) {
-out_race:
- /*
- * We raced with a task exiting - just return:
- */
pr_debug("couldn't open %s\n", filename);
return 0;
}
- memset(&event->comm, 0, sizeof(event->comm));
-
- while (!event->comm.comm[0] || !event->comm.pid) {
+ while (!comm[0] || (tgid < 0)) {
if (fgets(bf, sizeof(bf), fp) == NULL) {
- pr_warning("couldn't get COMM and pgid, malformed %s\n", filename);
- goto out;
+ pr_warning("couldn't get COMM and pgid, malformed %s\n",
+ filename);
+ break;
}
if (memcmp(bf, "Name:", 5) == 0) {
@@ -81,16 +71,46 @@
while (*name && isspace(*name))
++name;
size = strlen(name) - 1;
- memcpy(event->comm.comm, name, size++);
+ if (size >= len)
+ size = len - 1;
+ memcpy(comm, name, size);
+
} else if (memcmp(bf, "Tgid:", 5) == 0) {
char *tgids = bf + 5;
while (*tgids && isspace(*tgids))
++tgids;
- tgid = event->comm.pid = atoi(tgids);
+ tgid = atoi(tgids);
}
}
+ fclose(fp);
+
+ return tgid;
+}
+
+static pid_t perf_event__synthesize_comm(struct perf_tool *tool,
+ union perf_event *event, pid_t pid,
+ int full,
+ perf_event__handler_t process,
+ struct machine *machine)
+{
+ char filename[PATH_MAX];
+ size_t size;
+ DIR *tasks;
+ struct dirent dirent, *next;
+ pid_t tgid;
+
+ memset(&event->comm, 0, sizeof(event->comm));
+
+ tgid = perf_event__get_comm_tgid(pid, event->comm.comm,
+ sizeof(event->comm.comm));
+ if (tgid < 0)
+ goto out;
+
+ event->comm.pid = tgid;
event->comm.header.type = PERF_RECORD_COMM;
+
+ size = strlen(event->comm.comm) + 1;
size = ALIGN(size, sizeof(u64));
memset(event->comm.comm + size, 0, machine->id_hdr_size);
event->comm.header.size = (sizeof(event->comm) -
@@ -106,8 +126,10 @@
snprintf(filename, sizeof(filename), "/proc/%d/task", pid);
tasks = opendir(filename);
- if (tasks == NULL)
- goto out_race;
+ if (tasks == NULL) {
+ pr_debug("couldn't open %s\n", filename);
+ return 0;
+ }
while (!readdir_r(tasks, &dirent, &next) && next) {
char *end;
@@ -115,6 +137,17 @@
if (*end)
continue;
+ /* already have tgid; jut want to update the comm */
+ (void) perf_event__get_comm_tgid(pid, event->comm.comm,
+ sizeof(event->comm.comm));
+
+ size = strlen(event->comm.comm) + 1;
+ size = ALIGN(size, sizeof(u64));
+ memset(event->comm.comm + size, 0, machine->id_hdr_size);
+ event->comm.header.size = (sizeof(event->comm) -
+ (sizeof(event->comm.comm) - size) +
+ machine->id_hdr_size);
+
event->comm.tid = pid;
process(tool, event, &synth_sample, machine);
@@ -122,8 +155,6 @@
closedir(tasks);
out:
- fclose(fp);
-
return tgid;
}