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authorDavid Ahern <dsahern@gmail.com>2011-12-22 11:30:01 -0700
committerArnaldo Carvalho de Melo <acme@redhat.com>2011-12-23 16:10:40 -0200
commitdefd8d38773cf9e01c69a903d04d5895b78ee74f (patch)
tree1b6bba5c215fc09e499d7e364dbc1f32479dea23 /tools/perf
parentfb2baceb5a64990163e93b77ee205d0173202ee6 (diff)
downloadlinux-linaro-stable-defd8d38773cf9e01c69a903d04d5895b78ee74f.tar.gz
perf tools: Fix comm for processes with named threads
perf does not properly handle monitoring of processes with named threads. For example: $ ps -C myapp -L PID LWP TTY TIME CMD 25118 25118 ? 00:00:00 myapp 25118 25119 ? 00:00:00 myapp:worker perf record -e cs -c 1 -fo /tmp/perf.data -p 25118 -- sleep 10 perf report --stdio -i /tmp/perf.data 100.00% myapp:worker [kernel.kallsyms] [k] perf_event_task_sched_out The process name is set to the name of the last thread it finds for the process. The Problem: perf-top and perf-record both create a thread_map of threads to be monitored. That map is used in perf_event__synthesize_thread_map which loops over the entries in thread_map and calls __event__synthesize_thread to generate COMM and MMAP events. __event__synthesize_thread calls perf_event__synthesize_comm which opens /proc/pid/status, reads the name of the task and its thread group id. That's all fine. The problem is that it then reads /proc/pid/task and generates COMM events for each task it finds - but using the name found in /proc/pid/status where pid is the thread of interest. The end result (looping over thread_map + synthesizing comm events for each thread each time) means the name of the last thread processed sets the name for all threads in the process - which is not good for multithreaded processes with named threads. The Fix: perf_event__synthesize_comm has an input argument (full) that decides whether to process task entries for each pid it is passed. It currently never set to 0 (perf_event__synthesize_comm has a single caller and it always passes the value 1). Let's fix that. Add the full input argument to __event__synthesize_thread which passes it to perf_event__synthesize_comm. For thread/process monitoring set full to 0 which means COMM and MMAP events are only generated for the pid passed to it. For system wide monitoring set full to 1 so that COMM events are generated for all threads in a process. Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Ingo Molnar <mingo@elte.hu> Cc: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/1324578603-12762-2-git-send-email-dsahern@gmail.com Signed-off-by: David Ahern <dsahern@gmail.com> Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Diffstat (limited to 'tools/perf')
-rw-r--r--tools/perf/util/event.c37
1 files changed, 32 insertions, 5 deletions
diff --git a/tools/perf/util/event.c b/tools/perf/util/event.c
index b7c7f39a8f6d..a5787260181a 100644
--- a/tools/perf/util/event.c
+++ b/tools/perf/util/event.c
@@ -261,11 +261,12 @@ int perf_event__synthesize_modules(struct perf_tool *tool,
static int __event__synthesize_thread(union perf_event *comm_event,
union perf_event *mmap_event,
- pid_t pid, perf_event__handler_t process,
+ pid_t pid, int full,
+ perf_event__handler_t process,
struct perf_tool *tool,
struct machine *machine)
{
- pid_t tgid = perf_event__synthesize_comm(tool, comm_event, pid, 1,
+ pid_t tgid = perf_event__synthesize_comm(tool, comm_event, pid, full,
process, machine);
if (tgid == -1)
return -1;
@@ -279,7 +280,7 @@ int perf_event__synthesize_thread_map(struct perf_tool *tool,
struct machine *machine)
{
union perf_event *comm_event, *mmap_event;
- int err = -1, thread;
+ int err = -1, thread, j;
comm_event = malloc(sizeof(comm_event->comm) + machine->id_hdr_size);
if (comm_event == NULL)
@@ -292,11 +293,37 @@ int perf_event__synthesize_thread_map(struct perf_tool *tool,
err = 0;
for (thread = 0; thread < threads->nr; ++thread) {
if (__event__synthesize_thread(comm_event, mmap_event,
- threads->map[thread],
+ threads->map[thread], 0,
process, tool, machine)) {
err = -1;
break;
}
+
+ /*
+ * comm.pid is set to thread group id by
+ * perf_event__synthesize_comm
+ */
+ if ((int) comm_event->comm.pid != threads->map[thread]) {
+ bool need_leader = true;
+
+ /* is thread group leader in thread_map? */
+ for (j = 0; j < threads->nr; ++j) {
+ if ((int) comm_event->comm.pid == threads->map[j]) {
+ need_leader = false;
+ break;
+ }
+ }
+
+ /* if not, generate events for it */
+ if (need_leader &&
+ __event__synthesize_thread(comm_event,
+ mmap_event,
+ comm_event->comm.pid, 0,
+ process, tool, machine)) {
+ err = -1;
+ break;
+ }
+ }
}
free(mmap_event);
out_free_comm:
@@ -333,7 +360,7 @@ int perf_event__synthesize_threads(struct perf_tool *tool,
if (*end) /* only interested in proper numerical dirents */
continue;
- __event__synthesize_thread(comm_event, mmap_event, pid,
+ __event__synthesize_thread(comm_event, mmap_event, pid, 1,
process, tool, machine);
}