Em Tue, Feb 25, 2014 at 10:43:47PM -0500, Don Zickus escreveu:
> Currently if a process creates a bunch of threads using pthread_create
> and then perf is run in system_wide mode, the mmaps for those threads
> are not captured with a synthesized mmap event.
>
> The reason is those threads are not visible when walking the /proc/
> directory looking for /proc/<pid>/maps files. Instead they are discovered
> using the /proc/<pid>/tasks file (which the synthesized comm event uses).
>
> This causes problems when a program is trying to map a data address to a
> tid. Because the tid has no maps, the event is dropped. Changing the program
> to look up using the pid instead of the tid, finds the correct maps but
> creates
> ugly hacks in the program to carry the correct tid around.
>
> Fix this by synthesizing mmap events for each tid found in the
> /proc/<pid>/tasks
> file.
This seems to cover two problems, the first is for mmap/mmap2 event
processing to lookup pid/tid instead of pid/pid, the other one is to
iterate thru /proc/pid/tasks/, so this needes spliting up.
Now looking at the /tasks/ part...
> This may not be entirely clean but it seems to work.
>
> Signed-off-by: Don Zickus <dzic...@redhat.com>
> ---
> tools/perf/util/event.c | 15 +++++++++++----
> tools/perf/util/machine.c | 4 ++--
> 2 files changed, 13 insertions(+), 6 deletions(-)
>
> diff --git a/tools/perf/util/event.c b/tools/perf/util/event.c
> index 086c7c8..09c53bb 100644
> --- a/tools/perf/util/event.c
> +++ b/tools/perf/util/event.c
> @@ -93,10 +93,13 @@ static pid_t perf_event__get_comm_tgid(pid_t pid, char
> *comm, size_t len)
> }
>
> static pid_t perf_event__synthesize_comm(struct perf_tool *tool,
> - union perf_event *event, pid_t pid,
> + union perf_event *event,
> + union perf_event *mmap_event,
> + pid_t pid,
> int full,
> perf_event__handler_t process,
> - struct machine *machine)
> + struct machine *machine,
> + bool mmap_data)
> {
> char filename[PATH_MAX];
> size_t size;
> @@ -168,6 +171,10 @@ static pid_t perf_event__synthesize_comm(struct
> perf_tool *tool,
> tgid = -1;
> break;
> }
> +
> + /* process the thread's maps too */
> + perf_event__synthesize_mmap_events(tool, mmap_event, pid, tgid,
> + process, machine, mmap_data);
> }
>
> closedir(tasks);
> @@ -331,8 +338,8 @@ static int __event__synthesize_thread(union perf_event
> *comm_event,
> struct perf_tool *tool,
> struct machine *machine, bool mmap_data)
> {
> - pid_t tgid = perf_event__synthesize_comm(tool, comm_event, pid, full,
> - process, machine);
> + pid_t tgid = perf_event__synthesize_comm(tool, comm_event, mmap_event,
> pid,
> + full, process, machine,
> mmap_data);
> if (tgid == -1)
> return -1;
> return perf_event__synthesize_mmap_events(tool, mmap_event, pid, tgid,
> diff --git a/tools/perf/util/machine.c b/tools/perf/util/machine.c
> index 813e94e..eb26544 100644
> --- a/tools/perf/util/machine.c
> +++ b/tools/perf/util/machine.c
> @@ -1026,7 +1026,7 @@ int machine__process_mmap2_event(struct machine
> *machine,
> }
>
> thread = machine__findnew_thread(machine, event->mmap2.pid,
> - event->mmap2.pid);
> + event->mmap2.tid);
> if (thread == NULL)
> goto out_problem;
>
> @@ -1074,7 +1074,7 @@ int machine__process_mmap_event(struct machine
> *machine, union perf_event *event
> }
>
> thread = machine__findnew_thread(machine, event->mmap.pid,
> - event->mmap.pid);
> + event->mmap.tid);
> if (thread == NULL)
> goto out_problem;
>
> --
> 1.7.11.7
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