perf tools: Speed up thread map generation

When trying to capture perf data on a system running spejbb2013, perf
hung for about 15 minutes.  This is because it took that long to gather
about 10,000 thread maps and process them.

I don't think a user wants to wait that long.

Instead, recognize that thread maps are roughly equivalent to pid maps
and just quickly copy those instead.

To do this, I synthesize 'fork' events, this eventually calls
thread__fork() and copies the maps over.

The overhead goes from 15 minutes down to about a few seconds.

--
V2: based on Jiri's comments, moved malloc up a level
    and made sure the memory was freed

Signed-off-by: Don Zickus <dzickus@redhat.com>
Acked-by: Jiri Olsa <jolsa@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Joe Mario <jmario@redhat.com>
Link: http://lkml.kernel.org/r/1394808224-113774-1-git-send-email-dzickus@redhat.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

1 files changed, 51 insertions, 8 deletions

diff --git a/tools/perf/util/event.c b/tools/perf/util/event.c
index 55eebe936513..3e580be0f6fb 100644
--- a/tools/perf/util/event.c
+++ b/tools/perf/util/event.c
@@ -129,6 +129,28 @@ out:
         return tgid;
 }
 
+static int perf_event__synthesize_fork(struct perf_tool *tool,
+                                       union perf_event *event, pid_t pid,
+                                       pid_t tgid, perf_event__handler_t process,
+                                       struct machine *machine)
+{
+        memset(&event->fork, 0, sizeof(event->fork) + machine->id_hdr_size);
+
+        /* this is really a clone event but we use fork to synthesize it */
+        event->fork.ppid = tgid;
+        event->fork.ptid = tgid;
+        event->fork.pid  = tgid;
+        event->fork.tid  = pid;
+        event->fork.header.type = PERF_RECORD_FORK;
+
+        event->fork.header.size = (sizeof(event->fork) + machine->id_hdr_size);
+
+        if (process(tool, event, &synth_sample, machine) != 0)
+                return -1;
+
+        return 0;
+}
+
 int perf_event__synthesize_mmap_events(struct perf_tool *tool,
                                        union perf_event *event,
                                        pid_t pid, pid_t tgid,
@@ -278,6 +300,7 @@ int perf_event__synthesize_modules(struct perf_tool *tool,
 
 static int __event__synthesize_thread(union perf_event *comm_event,
                                       union perf_event *mmap_event,
+                                      union perf_event *fork_event,
                                       pid_t pid, int full,
                                           perf_event__handler_t process,
                                       struct perf_tool *tool,
@@ -326,9 +349,15 @@ static int __event__synthesize_thread(union perf_event *comm_event,
                 if (tgid == -1)
                         return -1;
 
-                /* process the thread's maps too */
-                rc = perf_event__synthesize_mmap_events(tool, mmap_event, _pid, tgid,
-                                                        process, machine, mmap_data);
+                if (_pid == pid) {
+                        /* process the parent's maps too */
+                        rc = perf_event__synthesize_mmap_events(tool, mmap_event, pid, tgid,
+                                                process, machine, mmap_data);
+                } else {
+                        /* only fork the tid's map, to save time */
+                        rc = perf_event__synthesize_fork(tool, fork_event, _pid, tgid,
+                                                 process, machine);
+                }
 
                 if (rc)
                         return rc;
@@ -344,7 +373,7 @@ int perf_event__synthesize_thread_map(struct perf_tool *tool,
                                       struct machine *machine,
                                       bool mmap_data)
 {
-        union perf_event *comm_event, *mmap_event;
+        union perf_event *comm_event, *mmap_event, *fork_event;
         int err = -1, thread, j;
 
         comm_event = malloc(sizeof(comm_event->comm) + machine->id_hdr_size);
@@ -355,9 +384,14 @@ int perf_event__synthesize_thread_map(struct perf_tool *tool,
         if (mmap_event == NULL)
                 goto out_free_comm;
 
+        fork_event = malloc(sizeof(fork_event->fork) + machine->id_hdr_size);
+        if (fork_event == NULL)
+                goto out_free_mmap;
+
         err = 0;
         for (thread = 0; thread < threads->nr; ++thread) {
                 if (__event__synthesize_thread(comm_event, mmap_event,
+                                               fork_event,
                                                threads->map[thread], 0,
                                                process, tool, machine,
                                                mmap_data)) {
@@ -383,6 +417,7 @@ int perf_event__synthesize_thread_map(struct perf_tool *tool,
                         /* if not, generate events for it */
                         if (need_leader &&
                             __event__synthesize_thread(comm_event, mmap_event,
+                                                       fork_event,
                                                        comm_event->comm.pid, 0,
                                                        process, tool, machine,
                                                        mmap_data)) {
@@ -391,6 +426,8 @@ int perf_event__synthesize_thread_map(struct perf_tool *tool,
                         }
                 }
         }
+        free(fork_event);
+out_free_mmap:
         free(mmap_event);
 out_free_comm:
         free(comm_event);
@@ -405,7 +442,7 @@ int perf_event__synthesize_threads(struct perf_tool *tool,
         DIR *proc;
         char proc_path[PATH_MAX];
         struct dirent dirent, *next;
-        union perf_event *comm_event, *mmap_event;
+        union perf_event *comm_event, *mmap_event, *fork_event;
         int err = -1;
 
         comm_event = malloc(sizeof(comm_event->comm) + machine->id_hdr_size);
@@ -416,6 +453,10 @@ int perf_event__synthesize_threads(struct perf_tool *tool,
         if (mmap_event == NULL)
                 goto out_free_comm;
 
+        fork_event = malloc(sizeof(fork_event->fork) + machine->id_hdr_size);
+        if (fork_event == NULL)
+                goto out_free_mmap;
+
         if (machine__is_default_guest(machine))
                 return 0;
 
@@ -423,7 +464,7 @@ int perf_event__synthesize_threads(struct perf_tool *tool,
         proc = opendir(proc_path);
 
         if (proc == NULL)
-                goto out_free_mmap;
+                goto out_free_fork;
 
         while (!readdir_r(proc, &dirent, &next) && next) {
                 char *end;
@@ -435,12 +476,14 @@ int perf_event__synthesize_threads(struct perf_tool *tool,
                  * We may race with exiting thread, so don't stop just because
                  * one thread couldn't be synthesized.
                  */
-                __event__synthesize_thread(comm_event, mmap_event, pid, 1,
-                                           process, tool, machine, mmap_data);
+                __event__synthesize_thread(comm_event, mmap_event, fork_event, pid,
+                                           1, process, tool, machine, mmap_data);
         }
 
         err = 0;
         closedir(proc);
+out_free_fork:
+        free(fork_event);
 out_free_mmap:
         free(mmap_event);
 out_free_comm: