perf evlist: Introduce {prepare,start}_workload refactored from 'perf record'

So that we can easily start a workload in other tools.

Cc: David Ahern <dsahern@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/n/tip-zdsksd4aphu0nltg2lpwsw3x@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

1 files changed, 13 insertions, 68 deletions

diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
index c3ac5415c097..4799195ed246 100644
--- a/tools/perf/builtin-record.c
+++ b/tools/perf/builtin-record.c
@@ -47,11 +47,9 @@ static struct perf_record_opts record_opts = {
 static unsigned int             page_size;
 static unsigned int             mmap_pages                      = UINT_MAX;
 static int                      output;
-static int                      pipe_output                     =      0;
 static const char               *output_name                    = NULL;
 static bool                     group                           =  false;
 static int                      realtime_prio                   =      0;
-static pid_t                    child_pid                       =     -1;
 static enum write_mode_t        write_mode                      = WRITE_FORCE;
 static bool                     no_buildid                      =  false;
 static bool                     no_buildid_cache                =  false;
@@ -144,9 +142,9 @@ static void sig_atexit(void)
 {
         int status;
 
-        if (child_pid > 0) {
+        if (evsel_list->workload.pid > 0) {
                 if (!child_finished)
-                        kill(child_pid, SIGTERM);
+                        kill(evsel_list->workload.pid, SIGTERM);
 
                 wait(&status);
                 if (WIFSIGNALED(status))
@@ -304,7 +302,7 @@ static int process_buildids(void)
 
 static void atexit_header(void)
 {
-        if (!pipe_output) {
+        if (!record_opts.pipe_output) {
                 session->header.data_size += bytes_written;
 
                 if (!no_buildid)
@@ -377,9 +375,7 @@ static int __cmd_record(int argc, const char **argv)
         int flags;
         int err;
         unsigned long waking = 0;
-        int child_ready_pipe[2], go_pipe[2];
         const bool forks = argc > 0;
-        char buf;
         struct machine *machine;
 
         progname = argv[0];
@@ -391,20 +387,15 @@ static int __cmd_record(int argc, const char **argv)
         signal(SIGINT, sig_handler);
         signal(SIGUSR1, sig_handler);
 
-        if (forks && (pipe(child_ready_pipe) < 0 || pipe(go_pipe) < 0)) {
-                perror("failed to create pipes");
-                exit(-1);
-        }
-
         if (!output_name) {
                 if (!fstat(STDOUT_FILENO, &st) && S_ISFIFO(st.st_mode))
-                        pipe_output = true;
+                        record_opts.pipe_output = true;
                 else
                         output_name = "perf.data";
         }
         if (output_name) {
                 if (!strcmp(output_name, "-"))
-                        pipe_output = true;
+                        record_opts.pipe_output = true;
                 else if (!stat(output_name, &st) && st.st_size) {
                         if (write_mode == WRITE_FORCE) {
                                 char oldname[PATH_MAX];
@@ -424,7 +415,7 @@ static int __cmd_record(int argc, const char **argv)
         else
                 flags |= O_TRUNC;
 
-        if (pipe_output)
+        if (record_opts.pipe_output)
                 output = STDOUT_FILENO;
         else
                 output = open(output_name, flags, S_IRUSR | S_IWUSR);
@@ -470,57 +461,11 @@ static int __cmd_record(int argc, const char **argv)
                 mmap_pages = (512 * 1024) / page_size;
 
         if (forks) {
-                child_pid = fork();
-                if (child_pid < 0) {
-                        perror("failed to fork");
-                        exit(-1);
-                }
-
-                if (!child_pid) {
-                        if (pipe_output)
-                                dup2(2, 1);
-                        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.
-                         */
-                        if (read(go_pipe[0], &buf, 1) == -1)
-                                perror("unable to read pipe");
-
-                        execvp(argv[0], (char **)argv);
-
-                        perror(argv[0]);
-                        kill(getppid(), SIGUSR1);
-                        exit(-1);
-                }
-
-                if (!record_opts.system_wide && record_opts.target_tid == -1 && record_opts.target_pid == -1)
-                        evsel_list->threads->map[0] = child_pid;
-
-                close(child_ready_pipe[1]);
-                close(go_pipe[0]);
-                /*
-                 * wait for child to settle
-                 */
-                if (read(child_ready_pipe[0], &buf, 1) == -1) {
-                        perror("unable to read pipe");
-                        exit(-1);
+                err = perf_evlist__prepare_workload(evsel_list, &record_opts, argv);
+                if (err < 0) {
+                        pr_err("Couldn't run the workload!\n");
+                        goto out_delete_session;
                 }
-                close(child_ready_pipe[0]);
         }
 
         open_counters(evsel_list);
@@ -530,7 +475,7 @@ static int __cmd_record(int argc, const char **argv)
          */
         atexit(atexit_header);
 
-        if (pipe_output) {
+        if (record_opts.pipe_output) {
                 err = perf_header__write_pipe(output);
                 if (err < 0)
                         return err;
@@ -543,7 +488,7 @@ static int __cmd_record(int argc, const char **argv)
 
         post_processing_offset = lseek(output, 0, SEEK_CUR);
 
-        if (pipe_output) {
+        if (record_opts.pipe_output) {
                 err = perf_session__synthesize_attrs(session,
                                                      process_synthesized_event);
                 if (err < 0) {
@@ -629,7 +574,7 @@ static int __cmd_record(int argc, const char **argv)
          * Let the child rip
          */
         if (forks)
-                close(go_pipe[1]);
+                perf_evlist__start_workload(evsel_list);
 
         for (;;) {
                 int hits = samples;