diff options
| -rw-r--r-- | tools/perf/builtin-stat.c | 64 |
1 files changed, 50 insertions, 14 deletions
diff --git a/tools/perf/builtin-stat.c b/tools/perf/builtin-stat.c index c5a290727a92..201ef2367dcb 100644 --- a/tools/perf/builtin-stat.c +++ b/tools/perf/builtin-stat.c @@ -99,7 +99,7 @@ static u64 runtime_cycles_noise; #define ERR_PERF_OPEN \ "Error: counter %d, sys_perf_counter_open() syscall returned with %d (%s)\n" -static void create_perf_stat_counter(int counter) +static void create_perf_stat_counter(int counter, int pid) { struct perf_counter_attr *attr = attrs + counter; @@ -119,7 +119,7 @@ static void create_perf_stat_counter(int counter) attr->inherit = inherit; attr->disabled = 1; - fd[0][counter] = sys_perf_counter_open(attr, 0, -1, -1, 0); + fd[0][counter] = sys_perf_counter_open(attr, pid, -1, -1, 0); if (fd[0][counter] < 0 && verbose) fprintf(stderr, ERR_PERF_OPEN, counter, fd[0][counter], strerror(errno)); @@ -205,12 +205,58 @@ static int run_perf_stat(int argc, const char **argv) int status = 0; int counter; int pid; + int child_ready_pipe[2], go_pipe[2]; + char buf; if (!system_wide) nr_cpus = 1; + if (pipe(child_ready_pipe) < 0 || pipe(go_pipe) < 0) { + perror("failed to create pipes"); + exit(1); + } + + if ((pid = fork()) < 0) + perror("failed to fork"); + + if (!pid) { + close(child_ready_pipe[0]); + close(go_pipe[1]); + fcntl(go_pipe[0], F_SETFD, FD_CLOEXEC); + + /* + * Do a dummy execvp to get the PLT entry resolved, + * so we avoid the resolver overhead on the real + * execvp call. + */ + execvp("", (char **)argv); + + /* + * Tell the parent we're ready to go + */ + close(child_ready_pipe[1]); + + /* + * Wait until the parent tells us to go. + */ + read(go_pipe[0], &buf, 1); + + execvp(argv[0], (char **)argv); + + perror(argv[0]); + exit(-1); + } + + /* + * Wait for the child to be ready to exec. + */ + close(child_ready_pipe[1]); + close(go_pipe[0]); + read(child_ready_pipe[0], &buf, 1); + close(child_ready_pipe[0]); + for (counter = 0; counter < nr_counters; counter++) - create_perf_stat_counter(counter); + create_perf_stat_counter(counter, pid); /* * Enable counters and exec the command: @@ -218,19 +264,9 @@ static int run_perf_stat(int argc, const char **argv) t0 = rdclock(); prctl(PR_TASK_PERF_COUNTERS_ENABLE); - if ((pid = fork()) < 0) - perror("failed to fork"); - - if (!pid) { - if (execvp(argv[0], (char **)argv)) { - perror(argv[0]); - exit(-1); - } - } - + close(go_pipe[1]); wait(&status); - prctl(PR_TASK_PERF_COUNTERS_DISABLE); t1 = rdclock(); walltime_nsecs[run_idx] = t1 - t0; |