1. 07 3月, 2018 9 次提交
  2. 06 3月, 2018 3 次提交
  3. 05 3月, 2018 27 次提交
  4. 27 2月, 2018 1 次提交
    • J
      perf stat: Ignore error thread when enabling system-wide --per-thread · ab6c79b8
      Jin Yao 提交于
      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: NJin Yao <yao.jin@linux.intel.com>
      Acked-by: NJiri Olsa <jolsa@kernel.org>
      Tested-by: NArnaldo 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.comSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>
      ab6c79b8