perf tools: Add time out to force stop proc map processing

System wide sampling like 'perf top' or 'perf record -a' read all
threads /proc/xxx/maps before sampling. If there are any threads which
generating a keeping growing huge maps, perf will do infinite loop
during synthesizing. Nothing will be sampled.

This patch fixes this issue by adding per-thread timeout to force stop
this kind of endless proc map processing.

PERF_RECORD_MISC_PROC_MAP_PARSE_TIME_OUT is introduced to indicate that
the mmap record are truncated by time out. User will get warning
notification when truncated mmap records are detected.

Reported-by: Ying Huang <ying.huang@intel.com>
Signed-off-by: Kan Liang <kan.liang@intel.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: David Ahern <dsahern@gmail.com>
Cc: Ying Huang <ying.huang@intel.com>
Link: http://lkml.kernel.org/r/1434549071-25611-1-git-send-email-kan.liang@intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

1 files changed, 11 insertions, 0 deletions

diff --git a/tools/perf/util/session.c b/tools/perf/util/session.c
index c371336d1eb2..2d882fd1f1b9 100644
--- a/tools/perf/util/session.c
+++ b/tools/perf/util/session.c
@@ -1064,6 +1064,8 @@ static int machines__deliver_event(struct machines *machines,
         case PERF_RECORD_MMAP:
                 return tool->mmap(tool, event, sample, machine);
         case PERF_RECORD_MMAP2:
+                if (event->header.misc & PERF_RECORD_MISC_PROC_MAP_PARSE_TIMEOUT)
+                        ++evlist->stats.nr_proc_map_timeout;
                 return tool->mmap2(tool, event, sample, machine);
         case PERF_RECORD_COMM:
                 return tool->comm(tool, event, sample, machine);
@@ -1360,6 +1362,15 @@ static void perf_session__warn_about_errors(const struct perf_session *session)
                 ui__warning("%u out of order events recorded.\n", oe->nr_unordered_events);
 
         events_stats__auxtrace_error_warn(stats);
+
+        if (stats->nr_proc_map_timeout != 0) {
+                ui__warning("%d map information files for pre-existing threads were\n"
+                            "not processed, if there are samples for addresses they\n"
+                            "will not be resolved, you may find out which are these\n"
+                            "threads by running with -v and redirecting the output\n"
+                            "to a file.\n",
+                            stats->nr_proc_map_timeout);
+        }
 }
 
 static int perf_session__flush_thread_stack(struct thread *thread,