Re: [PATCH] perf, tools: Stop perf stat -p when profiled processexits v3

From: David Ahern
Date: Thu Sep 13 2012 - 16:23:19 EST

On 9/13/12 9:58 AM, Andi Kleen wrote:
From: Andi Kleen <ak@xxxxxxxxxxxxxxx>

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@xxxxxxxxxxxxxxx>
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 = &&
+ access("/proc", X_OK) == 0 &&
+ !strchr(, ',');
+ if (check_proc)
+ snprintf(piddir, sizeof piddir, "/proc/%d",
+ atoi(;
+ 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.

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