• Milian Wolff's avatar
    perf stat: Wait for the correct child · dfc9eec7
    Milian Wolff authored
    When packaging the perf userland application into an AppImage, the
    wait() call in perf stat returned too early. It turned out that some
    other child process exited, but not the one perf stat launched:
    
      $ sudo strace -e fork,execve,clone,wait4 -f ./perf-x86_64.AppImage stat sleep 1
      execve("./perf-git.3a73b7f9-x86_64.AppImage", ["./perf-git.3a73b7f9-x86_64.AppIm"..., "stat", "sleep", "1"], 0x7ffec1bbf050 /* 18 vars */) = 0
      clone(child_stack=NULL, flags=CLONE_CHILD_CLEARTID|CLONE_CHILD_SETTID|SIGCHLD, child_tidptr=0x7f6a6e7efe50) = 3912
      strace: Process 3912 attached
      [pid  3912] clone(child_stack=NULL, flags=CLONE_CHILD_CLEARTID|CLONE_CHILD_SETTID|SIGCHLD, child_tidptr=0x7f6a6e7efe50) = 3914
      strace: Process 3914 attached
      [pid  3912] +++ exited with 0 +++
      [pid  3911] --- SIGCHLD {si_signo=SIGCHLD, si_code=CLD_EXITED, si_pid=3912, si_uid=0, si_status=0, si_utime=0, si_stime=0} ---
      [pid  3914] clone(strace: Process 3915 attached
      child_stack=0x7f6a6d9fefb0, flags=CLONE_VM|CLONE_FS|CLONE_FILES|CLONE_SIGHAND|CLONE_THREAD|CLONE_SYSVSEM|CLONE_SETTLS|CLONE_PARENT_SETTID|CLONE_CHILD_CLEARTID, parent_tidptr=0x7f6a6d9ff9d0, tls=0x7f6a6d9ff700, child_tidptr=0x7f6a6d9ff9d0) = 3915
      [pid  3911] execve("/tmp/.mount_perf-g6VYMpl/AppRun", ["./perf-git.3a73b7f9-x86_64.AppIm"..., "stat", "sleep", "1"], 0x14aab70 /* 21 vars */) = 0
      [pid  3911] clone(child_stack=NULL, flags=CLONE_CHILD_CLEARTID|CLONE_CHILD_SETTID|SIGCHLD, child_tidptr=0x7f4ae113c4d0) = 3916
      strace: Process 3916 attached
      [pid  3911] wait4(-1, [{WIFEXITED(s) && WEXITSTATUS(s) == 0}], 0, NULL) = 3912
      [pid  3916] execve("/usr/libexec/perf-core/sleep", ["sleep", "1"], 0x27d3650 /* 22 vars */) = -1 ENOENT (No such file or directory)
      [pid  3916] execve("/tmp/./sleep", ["sleep", "1"], 0x27d3650 /* 22 vars */) = -1 ENOENT (No such file or directory)
      [pid  3916] execve("/home/milian/.bin/sleep", ["sleep", "1"], 0x27d3650 /* 22 vars */) = -1 ENOENT (No such file or directory)
      [pid  3916] execve("/usr/lib/icecream/libexec/icecc/bin/sleep", ["sleep", "1"], 0x27d3650 /* 22 vars */) = -1 ENOENT (No such file or directory)
      [pid  3916] execve("/ssd2/milian/projects/compiled/other/bin/sleep", ["sleep", "1"], 0x27d3650 /* 22 vars */) = -1 ENOENT (No such file or directory)
      [pid  3916] execve("/home/milian/.bin/kf5/sleep", ["sleep", "1"], 0x27d3650 /* 22 vars */) = -1 ENOENT (No such file or directory)
      [pid  3916] execve("/ssd2/milian/projects/compiled/kf5/bin/sleep", ["sleep", "1"], 0x27d3650 /* 22 vars */) = -1 ENOENT (No such file or directory)
      [pid  3916] execve("/home/milian/projects/compiled/other/bin/sleep", ["sleep", "1"], 0x27d3650 /* 22 vars */) = -1 ENOENT (No such file or directory)
      [pid  3916] execve("/home/milian/projects/compiled/kf5/bin/sleep", ["sleep", "1"], 0x27d3650 /* 22 vars */) = -1 ENOENT (No such file or directory)
      [pid  3916] execve("/usr/local/sbin/sleep", ["sleep", "1"], 0x27d3650 /* 22 vars */) = -1 ENOENT (No such file or directory)
      [pid  3916] execve("/usr/local/bin/sleep", ["sleep", "1"], 0x27d3650 /* 22 vars */) = -1 ENOENT (No such file or directory)
      [pid  3916] execve("/usr/bin/sleep", ["sleep", "1"], 0x27d3650 /* 22 vars */
       Performance counter stats for 'sleep 1':
    
           <not counted>	task-clock
           <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
    
             0.000047194 seconds time elapsed
    
      [pid  3916] --- SIGTERM {si_signo=SIGTERM, si_code=SI_USER, si_pid=3911, si_uid=0} ---
      [pid  3916] +++ killed by SIGTERM +++
      [pid  3911] --- SIGCHLD {si_signo=SIGCHLD, si_code=CLD_KILLED, si_pid=3916, si_uid=0, si_status=SIGTERM, si_utime=0, si_stime=0} ---
      [pid  3915] --- SIGPIPE {si_signo=SIGPIPE, si_code=SI_USER, si_pid=3914, si_uid=0} ---
      [pid  3911] +++ exited with 0 +++
      [pid  3915] --- SIGHUP {si_signo=SIGHUP, si_code=SI_USER, si_pid=3914, si_uid=0} ---
      [pid  3915] +++ exited with 0 +++
      +++ exited with 0 +++
    
    This patch uses waitpid instead to ensure the call waits for the
    debuggee application launched by 'perf stat'. This fixes 'perf stat'
    when launched from an AppImage:
    
      $ ./perf-x86_64.AppImage stat sleep 1
    
       Performance counter stats for 'sleep 1':
    
              0.357235      task-clock (msec)         #    0.000 CPUs utilized
                     1      context-switches          #    0.003 M/sec
                     0      cpu-migrations            #    0.000 K/sec
                    50      page-faults               #    0.140 M/sec
               1269602      cycles                    #    3.554 GHz
                654278      instructions              #    0.52  insn per cycle
                129963      branches                  #  363.803 M/sec
                  7082      branch-misses             #    5.45% of all branches
    
           1.000633420 seconds time elapsed
    Signed-off-by: default avatarMilian Wolff <milian.wolff@kdab.com>
    Cc: David Ahern <dsahern@gmail.com>
    Cc: Namhyung Kim <namhyung@kernel.org>
    Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
    Link: http://lkml.kernel.org/r/20170912152523.4497-1-milian.wolff@kdab.comSigned-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
    dfc9eec7
builtin-stat.c 68.7 KB