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SubjectRe: [PATCH] perf, tools: Stop perf stat -p when profiled process exits v3
On 9/13/12 9:58 AM, Andi Kleen wrote:
> From: Andi Kleen <ak@linux.intel.com>
>
> When counting a process with perf stat -p check if the process died
> and exit collection if yes.
>
> v2: Add more checks, handle non -p again. Handle /proc not there.
> v3: Handle multi pid case. Fix non /proc error path
> Signed-off-by: Andi Kleen <ak@linux.intel.com>
> ---
> tools/perf/builtin-stat.c | 14 +++++++++++++-
> 1 files changed, 13 insertions(+), 1 deletions(-)
>
> diff --git a/tools/perf/builtin-stat.c b/tools/perf/builtin-stat.c
> index 861f0ae..b5e7df2 100644
> --- a/tools/perf/builtin-stat.c
> +++ b/tools/perf/builtin-stat.c
> @@ -536,7 +536,19 @@ static int run_perf_stat(int argc __used, const char **argv)
> if (WIFSIGNALED(status))
> psignal(WTERMSIG(status), argv[0]);
> } else {
> - while(!done) sleep(1);
> + char piddir[40];
> + int check_proc = target.pid &&
> + access("/proc", X_OK) == 0 &&
> + !strchr(target.pid, ',');
> + if (check_proc)
> + snprintf(piddir, sizeof piddir, "/proc/%d",
> + atoi(target.pid));
> + while(!done) {
> + sleep(1);
> + if (check_proc && access(piddir, X_OK) < 0 &&
> + errno == ENOENT)
> + break;
> + }
> }

I still think this is the wrong approach. A more complete solution would
monitor all of the targets given by the user. e.g.,

1. create a perf_target__parse_pid - all it needs to do is:
struct strlist *slist = strlist__new(false, pid_str);
and save that into the target struct. That line is currently done in
thread_map.c, thread_map__new_by_pid_str() and
thread_map__new_by_tid_str. Those functions can be altered to take the
slist instead of the string.

2. create a perf_target__is_alive that runs through each entry in the
slist (strlist__for_each(pos, slist)) and checks that it still exists.
As long as 1 target is alive it returns true. If no pid or tid is
specified it always returns true.

The is_alive function can be used by perf-top, perf-stat and perf-record
to know that its target has died so it can stop monitoring.


David


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