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perf stat: Better report failure to collect system wide stats 

Before:

[acme@doppio linux-2.6-tip]$ perf stat -a sleep 1s

 Performance counter stats for 'sleep 1s':

  <not counted>  task-clock-msecs
  <not counted>  context-switches
  <not counted>  CPU-migrations
  <not counted>  page-faults
  <not counted>  cycles
  <not counted>  instructions
  <not counted>  branches
  <not counted>  branch-misses
  <not counted>  cache-references
  <not counted>  cache-misses

    1.016998463  seconds time elapsed

[acme@doppio linux-2.6-tip]$

Now:

[acme@doppio linux-2.6-tip]$ perf stat -a sleep 1s
No permission to collect system-wide stats.
Consider tweaking /proc/sys/kernel/perf_event_paranoid.
[acme@doppio linux-2.6-tip]$

Reported-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Frédéric Weisbecker <fweisbec@gmail.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
LKML-Reference: <1269274229-20442-4-git-send-email-acme@infradead.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Arnaldo Carvalho de Melo 2010-03-22 13:10:28 -03:00 committed by Ingo Molnar
parent ca721e45b3
commit 084ab9f862
1 changed files with 28 additions and 11 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

39
tools/perf/builtin-stat.c
View File

@ -144,10 +144,11 @@ struct stats runtime_branches_stats;
#define ERR_PERF_OPEN \
"Error: counter %d, sys_perf_event_open() syscall returned with %d (%s)\n"
static void create_perf_stat_counter(int counter)
static int create_perf_stat_counter(int counter)
{
struct perf_event_attr *attr = attrs + counter;
int thread;
int ncreated = 0;
if (scale)
attr->read_format = PERF_FORMAT_TOTAL_TIME_ENABLED |
@ -159,9 +160,11 @@ static void create_perf_stat_counter(int counter)
for (cpu = 0; cpu < nr_cpus; cpu++) {
fd[cpu][counter][0] = sys_perf_event_open(attr,
-1, cpumap[cpu], -1, 0);
if (fd[cpu][counter][0] < 0 && verbose)
fprintf(stderr, ERR_PERF_OPEN, counter,
fd[cpu][counter][0], strerror(errno));
if (fd[cpu][counter][0] < 0)
pr_debug(ERR_PERF_OPEN, counter,
fd[cpu][counter][0], strerror(errno));
else
++ncreated;
}
} else {
attr->inherit = inherit;
@ -172,12 +175,16 @@ static void create_perf_stat_counter(int counter)
for (thread = 0; thread < thread_num; thread++) {
fd[0][counter][thread] = sys_perf_event_open(attr,
all_tids[thread], -1, -1, 0);
if (fd[0][counter][thread] < 0 && verbose)
fprintf(stderr, ERR_PERF_OPEN, counter,
fd[0][counter][thread],
strerror(errno));
if (fd[0][counter][thread] < 0)
pr_debug(ERR_PERF_OPEN, counter,
fd[0][counter][thread],
strerror(errno));
else
++ncreated;
}
}
return ncreated;
}
/*
@ -264,7 +271,7 @@ static int run_perf_stat(int argc __used, const char **argv)
{
unsigned long long t0, t1;
int status = 0;
int counter;
int counter, ncreated = 0;
int child_ready_pipe[2], go_pipe[2];
const bool forks = (argc > 0);
char buf;
@ -324,7 +331,16 @@ static int run_perf_stat(int argc __used, const char **argv)
}
for (counter = 0; counter < nr_counters; counter++)
create_perf_stat_counter(counter);
ncreated += create_perf_stat_counter(counter);
if (ncreated == 0) {
pr_err("No permission to collect %sstats.\n"
"Consider tweaking /proc/sys/kernel/perf_event_paranoid.\n",
system_wide ? "system-wide " : "");
if (child_pid != -1)
kill(child_pid, SIGTERM);
return -1;
}
/*
* Enable counters and exec the command:
@ -587,7 +603,8 @@ int cmd_stat(int argc, const char **argv, const char *prefix __used)
status = run_perf_stat(argc, argv);
}
print_stat(argc, argv);
if (status != -1)
print_stat(argc, argv);
return status;
}