Commit 084ab9f8 authored by Arnaldo Carvalho de Melo's avatar Arnaldo Carvalho de Melo Committed by Ingo Molnar
Browse files

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: default avatarIngo Molnar <mingo@elte.hu>
Signed-off-by: default avatarArnaldo 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: default avatarIngo Molnar <mingo@elte.hu>
parent ca721e45

tools/perf/builtin-stat.c

+28 −11
Original line number Diff line number Diff line
@@ -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,

			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,

			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:
@@ -587,6 +603,7 @@ int cmd_stat(int argc, const char **argv, const char *prefix __used) 
		status = run_perf_stat(argc, argv);

	}



	if (status != -1)

		print_stat(argc, argv);



	return status;

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