perf stat: Enable counters when collecting process-wide or system-wide data
Command 'perf stat' doesn't enable counters when collecting an
existing (by -p) process or system-wide statistics. Fix the
issue.
Change the condition of fork/exec subcommand. If there is a
subcommand parameter, perf always forks/execs it. The usage
example is:
# perf stat -a sleep 10
So this command could collect statistics for 10 seconds
precisely. User still could stop it by CTRL+C. Without the new
capability, user could only use CTRL+C to stop it without
precise time clock.
Another issue is 'perf stat -a' consumes 100% time of a full
single logical cpu. It has a bad impact on running workload.
Fix it by adding a sleep(1) in the while(!done) loop in function
run_perf_stat.
Signed-off-by: Zhang Yanmin <yanmin_zhang@linux.intel.com>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Avi Kivity <avi@redhat.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Sheng Yang <sheng@linux.intel.com>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Joerg Roedel <joro@8bytes.org>
Cc: Jes Sorensen <Jes.Sorensen@redhat.com>
Cc: Gleb Natapov <gleb@redhat.com>
Cc: Zachary Amsden <zamsden@redhat.com>
Cc: <zhiteng.huang@intel.com>
LKML-Reference: <1268922965-14774-1-git-send-email-acme@infradead.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/tools/perf/builtin-stat.c b/tools/perf/builtin-stat.c
index 95db31c..5f41244 100644
--- a/tools/perf/builtin-stat.c
+++ b/tools/perf/builtin-stat.c
@@ -159,8 +159,10 @@
}
} else {
attr->inherit = inherit;
- attr->disabled = 1;
- attr->enable_on_exec = 1;
+ if (target_pid == -1) {
+ attr->disabled = 1;
+ attr->enable_on_exec = 1;
+ }
fd[0][counter] = sys_perf_event_open(attr, pid, -1, -1, 0);
if (fd[0][counter] < 0 && verbose)
@@ -251,9 +253,9 @@
unsigned long long t0, t1;
int status = 0;
int counter;
- int pid = target_pid;
+ int pid;
int child_ready_pipe[2], go_pipe[2];
- const bool forks = (target_pid == -1 && argc > 0);
+ const bool forks = (argc > 0);
char buf;
if (!system_wide)
@@ -265,10 +267,10 @@
}
if (forks) {
- if ((pid = fork()) < 0)
+ if ((child_pid = fork()) < 0)
perror("failed to fork");
- if (!pid) {
+ if (!child_pid) {
close(child_ready_pipe[0]);
close(go_pipe[1]);
fcntl(go_pipe[0], F_SETFD, FD_CLOEXEC);
@@ -297,8 +299,6 @@
exit(-1);
}
- child_pid = pid;
-
/*
* Wait for the child to be ready to exec.
*/
@@ -309,6 +309,10 @@
close(child_ready_pipe[0]);
}
+ if (target_pid == -1)
+ pid = child_pid;
+ else
+ pid = target_pid;
for (counter = 0; counter < nr_counters; counter++)
create_perf_stat_counter(counter, pid);
@@ -321,7 +325,7 @@
close(go_pipe[1]);
wait(&status);
} else {
- while(!done);
+ while(!done) sleep(1);
}
t1 = rdclock();
@@ -459,7 +463,7 @@
static void skip_signal(int signo)
{
- if(target_pid != -1)
+ if(child_pid == -1)
done = 1;
signr = signo;