From: Zhang, Yanmin <[email protected]> 'perf record' starts counters before subcommand is execed, so the statistics is not precise because it includes data of some preparation steps. I fix it with the patch.
In addition, Change the condition to fork/exec subcommand. If there is a subcommand parameter, perf always fork/exec it. The usage example is: #perf record -f -a sleep 10 So this command could collect statistics for 10 seconds precisely. User still could stop it by CTRL+C. Without the new capability, user could only input CTRL+C to stop it without precise time clock. Signed-off-by: Zhang Yanmin <[email protected]> --- diff -Nraup linux-2.6_tip0317/tools/perf/builtin-record.c linux-2.6_tip0317_fixrecord/tools/perf/builtin-record.c --- linux-2.6_tip0317/tools/perf/builtin-record.c 2010-03-18 09:04:40.942263175 +0800 +++ linux-2.6_tip0317_fixrecord/tools/perf/builtin-record.c 2010-03-18 13:33:24.254359348 +0800 @@ -225,7 +225,7 @@ static struct perf_header_attr *get_head return h_attr; } -static void create_counter(int counter, int cpu, pid_t pid, bool forks) +static void create_counter(int counter, int cpu, pid_t pid) { char *filter = filters[counter]; struct perf_event_attr *attr = attrs + counter; @@ -275,10 +275,10 @@ static void create_counter(int counter, attr->mmap = track; attr->comm = track; attr->inherit = inherit; - attr->disabled = 1; - - if (forks) + if (target_pid == -1 && !system_wide) { + attr->disabled = 1; attr->enable_on_exec = 1; + } try_again: fd[nr_cpu][counter] = sys_perf_event_open(attr, pid, cpu, group_fd, 0); @@ -380,17 +380,15 @@ try_again: exit(-1); } } - - ioctl(fd[nr_cpu][counter], PERF_EVENT_IOC_ENABLE); } -static void open_counters(int cpu, pid_t pid, bool forks) +static void open_counters(int cpu, pid_t pid) { int counter; group_fd = -1; for (counter = 0; counter < nr_counters; counter++) - create_counter(counter, cpu, pid, forks); + create_counter(counter, cpu, pid); nr_cpu++; } @@ -425,7 +423,7 @@ static int __cmd_record(int argc, const int err; unsigned long waking = 0; int child_ready_pipe[2], go_pipe[2]; - const bool forks = target_pid == -1 && argc > 0; + const bool forks = argc > 0; char buf; page_size = sysconf(_SC_PAGE_SIZE); @@ -496,13 +494,13 @@ static int __cmd_record(int argc, const atexit(atexit_header); if (forks) { - pid = fork(); + child_pid = fork(); if (pid < 0) { perror("failed to fork"); exit(-1); } - if (!pid) { + if (!child_pid) { close(child_ready_pipe[0]); close(go_pipe[1]); fcntl(go_pipe[0], F_SETFD, FD_CLOEXEC); @@ -531,11 +529,6 @@ static int __cmd_record(int argc, const exit(-1); } - child_pid = pid; - - if (!system_wide) - target_pid = pid; - close(child_ready_pipe[1]); close(go_pipe[0]); /* @@ -548,13 +541,17 @@ static int __cmd_record(int argc, const close(child_ready_pipe[0]); } + if (forks && target_pid == -1 && !system_wide) + pid = child_pid; + else + pid = target_pid; if ((!system_wide && !inherit) || profile_cpu != -1) { - open_counters(profile_cpu, target_pid, forks); + open_counters(profile_cpu, pid); } else { nr_cpus = read_cpu_map(); for (i = 0; i < nr_cpus; i++) - open_counters(cpumap[i], target_pid, forks); + open_counters(cpumap[i], pid); } if (file_new) { -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
