From dfc9eec7716cc0a9f7eb743c703d74cd2d6085a0 Mon Sep 17 00:00:00 2001 From: Milian Wolff Date: Tue, 12 Sep 2017 17:25:23 +0200 Subject: [PATCH] perf stat: Wait for the correct child 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': task-clock context-switches cpu-migrations page-faults cycles instructions branches 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: Milian Wolff Cc: David Ahern Cc: Namhyung Kim Cc: Peter Zijlstra Link: http://lkml.kernel.org/r/20170912152523.4497-1-milian.wolff@kdab.com Signed-off-by: Arnaldo Carvalho de Melo --- tools/perf/builtin-stat.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/tools/perf/builtin-stat.c b/tools/perf/builtin-stat.c index 85e992d..69523ed 100644 --- a/tools/perf/builtin-stat.c +++ b/tools/perf/builtin-stat.c @@ -707,7 +707,7 @@ try_again: process_interval(); } } - wait(&status); + waitpid(child_pid, &status, 0); if (workload_exec_errno) { const char *emsg = str_error_r(workload_exec_errno, msg, sizeof(msg)); -- 2.7.4