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. Signed-off-by: Don Zickus <[email protected]> --- tools/perf/util/event.c | 39 ++++++++++++++++++++++++++++++++++++--- 1 files changed, 36 insertions(+), 3 deletions(-) --- Based on perf/core: 1c075d114d0f3be diff --git a/tools/perf/util/event.c b/tools/perf/util/event.c index 55eebe9..95e5649 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, @@ -287,6 +309,11 @@ static int __event__synthesize_thread(union perf_event *comm_event, DIR *tasks; struct dirent dirent, *next; pid_t tgid; + union perf_event *fork_event; + + fork_event = malloc(sizeof(fork_event->fork) + machine->id_hdr_size); + if (fork_event == NULL) + return -1; /* special case: only send one comm event using passed in pid */ if (!full) { @@ -326,9 +353,15 @@ 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; -- 1.7.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
