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ab6c79b819
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>
66 lines
1.7 KiB
C
66 lines
1.7 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef __PERF_THREAD_MAP_H
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#define __PERF_THREAD_MAP_H
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#include <sys/types.h>
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#include <stdio.h>
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#include <linux/refcount.h>
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struct thread_map_data {
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pid_t pid;
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char *comm;
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};
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struct thread_map {
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refcount_t refcnt;
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int nr;
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int err_thread;
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struct thread_map_data map[];
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};
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struct thread_map_event;
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struct thread_map *thread_map__new_dummy(void);
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struct thread_map *thread_map__new_by_pid(pid_t pid);
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struct thread_map *thread_map__new_by_tid(pid_t tid);
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struct thread_map *thread_map__new_by_uid(uid_t uid);
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struct thread_map *thread_map__new_all_cpus(void);
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struct thread_map *thread_map__new(pid_t pid, pid_t tid, uid_t uid);
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struct thread_map *thread_map__new_event(struct thread_map_event *event);
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struct thread_map *thread_map__get(struct thread_map *map);
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void thread_map__put(struct thread_map *map);
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struct thread_map *thread_map__new_str(const char *pid,
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const char *tid, uid_t uid, bool all_threads);
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struct thread_map *thread_map__new_by_tid_str(const char *tid_str);
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size_t thread_map__fprintf(struct thread_map *threads, FILE *fp);
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static inline int thread_map__nr(struct thread_map *threads)
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{
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return threads ? threads->nr : 1;
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}
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static inline pid_t thread_map__pid(struct thread_map *map, int thread)
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{
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return map->map[thread].pid;
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}
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static inline void
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thread_map__set_pid(struct thread_map *map, int thread, pid_t pid)
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{
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map->map[thread].pid = pid;
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}
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static inline char *thread_map__comm(struct thread_map *map, int thread)
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{
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return map->map[thread].comm;
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}
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void thread_map__read_comms(struct thread_map *threads);
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bool thread_map__has(struct thread_map *threads, pid_t pid);
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int thread_map__remove(struct thread_map *threads, int idx);
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#endif /* __PERF_THREAD_MAP_H */
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