From e5adfc3e7e774ba86f7bb725c6eef5f32df8630e Mon Sep 17 00:00:00 2001 From: Konstantin Khlebnikov Date: Tue, 7 Aug 2018 12:09:01 +0300 Subject: [PATCH] perf map: Synthesize maps only for thread group leader Threads share map_groups, all map events are merged into it. Thus we could send mmaps only for thread group leader. Otherwise it took ages to attach and record something from processes with many vmas and threads. Thread group leader could be already dead, but it seems perf cannot handle this case anyway. Testing dummy: #include #include #include #include #include void *thread(void *arg) { pause(); } int main(int argc, char **argv) { int threads = 10000; int vmas = 50000; pthread_t th; for (int i = 0; i < threads; i++) pthread_create(&th, NULL, thread, NULL); for (int i = 0; i < vmas; i++) mmap(NULL, 4096, (i & 1) ? PROT_READ : PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS | MAP_NORESERVE, -1, 0); sleep(60); return 0; } Comment by Jiri Olsa: We actualy synthesize the group leader (if we found one) for the thread even if it's not present in the thread_map, so the process maps are always in data. Signed-off-by: Konstantin Khlebnikov Acked-by: Jiri Olsa Cc: Alexander Shishkin Cc: Namhyung Kim Cc: Peter Zijlstra Link: http://lkml.kernel.org/r/153363294102.396323.6277944760215058174.stgit@buzz Signed-off-by: Arnaldo Carvalho de Melo --- tools/perf/util/event.c | 13 ++++++++++--- 1 file changed, 10 insertions(+), 3 deletions(-) diff --git a/tools/perf/util/event.c b/tools/perf/util/event.c index 0c8ecf0c78a4..0cd42150f712 100644 --- a/tools/perf/util/event.c +++ b/tools/perf/util/event.c @@ -541,10 +541,17 @@ static int __event__synthesize_thread(union perf_event *comm_event, tgid, process, machine) < 0) return -1; + /* + * send mmap only for thread group leader + * see thread__init_map_groups + */ + if (pid == tgid && + perf_event__synthesize_mmap_events(tool, mmap_event, pid, tgid, + process, machine, mmap_data, + proc_map_timeout)) + return -1; - return perf_event__synthesize_mmap_events(tool, mmap_event, pid, tgid, - process, machine, mmap_data, - proc_map_timeout); + return 0; } if (machine__is_default_guest(machine)) -- 2.30.2