linux/tools/perf/util/thread_map.h
Jin Yao ab6c79b819 perf stat: Ignore error thread when enabling system-wide --per-thread
If we execute 'perf stat --per-thread' with non-root account (even set
kernel.perf_event_paranoid = -1 yet), it reports the error:

  jinyao@skl:~$ perf stat --per-thread
  Error:
  You may not have permission to collect system-wide stats.

  Consider tweaking /proc/sys/kernel/perf_event_paranoid,
  which controls use of the performance events system by
  unprivileged users (without CAP_SYS_ADMIN).

  The current value is 2:

    -1: Allow use of (almost) all events by all users
        Ignore mlock limit after perf_event_mlock_kb without CAP_IPC_LOCK
  >= 0: Disallow ftrace function tracepoint by users without CAP_SYS_ADMIN
        Disallow raw tracepoint access by users without CAP_SYS_ADMIN
  >= 1: Disallow CPU event access by users without CAP_SYS_ADMIN
  >= 2: Disallow kernel profiling by users without CAP_SYS_ADMIN

  To make this setting permanent, edit /etc/sysctl.conf too, e.g.:

          kernel.perf_event_paranoid = -1

Perhaps the ptrace rule doesn't allow to trace some processes. But anyway
the global --per-thread mode had better ignore such errors and continue
working on other threads.

This patch will record the index of error thread in perf_evsel__open()
and remove this thread before retrying.

For example (run with non-root, kernel.perf_event_paranoid isn't set):

  jinyao@skl:~$ perf stat --per-thread
  ^C
   Performance counter stats for 'system wide':

         vmstat-3458    6.171984   cpu-clock:u (msec) #  0.000 CPUs utilized
           perf-3670    0.515599   cpu-clock:u (msec) #  0.000 CPUs utilized
         vmstat-3458   1,163,643   cycles:u           #  0.189 GHz
           perf-3670      40,881   cycles:u           #  0.079 GHz
         vmstat-3458   1,410,238   instructions:u     #  1.21  insn per cycle
           perf-3670       3,536   instructions:u     #  0.09  insn per cycle
         vmstat-3458     288,937   branches:u         # 46.814 M/sec
           perf-3670         936   branches:u         #  1.815 M/sec
         vmstat-3458      15,195   branch-misses:u    #  5.26% of all branches
           perf-3670          76   branch-misses:u    #  8.12% of all branches

        12.651675247 seconds time elapsed

Signed-off-by: Jin Yao <yao.jin@linux.intel.com>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Kan Liang <kan.liang@intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1516117388-10120-1-git-send-email-yao.jin@linux.intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2018-02-27 11:29:21 -03:00

66 lines
1.7 KiB
C

/* SPDX-License-Identifier: GPL-2.0 */
#ifndef __PERF_THREAD_MAP_H
#define __PERF_THREAD_MAP_H
#include <sys/types.h>
#include <stdio.h>
#include <linux/refcount.h>
struct thread_map_data {
pid_t pid;
char *comm;
};
struct thread_map {
refcount_t refcnt;
int nr;
int err_thread;
struct thread_map_data map[];
};
struct thread_map_event;
struct thread_map *thread_map__new_dummy(void);
struct thread_map *thread_map__new_by_pid(pid_t pid);
struct thread_map *thread_map__new_by_tid(pid_t tid);
struct thread_map *thread_map__new_by_uid(uid_t uid);
struct thread_map *thread_map__new_all_cpus(void);
struct thread_map *thread_map__new(pid_t pid, pid_t tid, uid_t uid);
struct thread_map *thread_map__new_event(struct thread_map_event *event);
struct thread_map *thread_map__get(struct thread_map *map);
void thread_map__put(struct thread_map *map);
struct thread_map *thread_map__new_str(const char *pid,
const char *tid, uid_t uid, bool all_threads);
struct thread_map *thread_map__new_by_tid_str(const char *tid_str);
size_t thread_map__fprintf(struct thread_map *threads, FILE *fp);
static inline int thread_map__nr(struct thread_map *threads)
{
return threads ? threads->nr : 1;
}
static inline pid_t thread_map__pid(struct thread_map *map, int thread)
{
return map->map[thread].pid;
}
static inline void
thread_map__set_pid(struct thread_map *map, int thread, pid_t pid)
{
map->map[thread].pid = pid;
}
static inline char *thread_map__comm(struct thread_map *map, int thread)
{
return map->map[thread].comm;
}
void thread_map__read_comms(struct thread_map *threads);
bool thread_map__has(struct thread_map *threads, pid_t pid);
int thread_map__remove(struct thread_map *threads, int idx);
#endif /* __PERF_THREAD_MAP_H */