simpleperf: wake up per sample in monitor cmd.

It is to show samples in real time.
Also flush stdout after printing each sample.

Bug: none
Test: run simpleperf_unit_test.
Change-Id: I7de8ae82deedb76d736c7635f6818ba7b6f440bc

3 files changed, 13 insertions, 0 deletions

diff --git a/simpleperf/cmd_monitor.cpp b/simpleperf/cmd_monitor.cpp
index 4f76bf24..0a1b792c 100644
--- a/simpleperf/cmd_monitor.cpp
+++ b/simpleperf/cmd_monitor.cpp
@@ -462,6 +462,7 @@ bool MonitorCommand::AdjustPerfEventLimit() {
 
 bool MonitorCommand::SetEventSelectionFlags() {
   event_selection_set_.SampleIdAll();
+  event_selection_set_.WakeupPerSample();
   if (fp_callchain_sampling_) {
     event_selection_set_.EnableFpCallChainSampling();
   } else if (dwarf_callchain_sampling_) {
@@ -512,6 +513,7 @@ void MonitorCommand::DumpSampleRecord(const SampleRecord& sr) {
   StringAppendF(&output, " pid=%u tid=%u", sr.tid_data.pid, sr.tid_data.tid);
   StringAppendF(&output, " cpu=%u", sr.cpu_data.cpu);
   printf("%s\n", output.c_str());
+  fflush(stdout);
 }
 
 void MonitorCommand::DumpSampleCallchain(const SampleRecord& sr) {
@@ -531,6 +533,7 @@ void MonitorCommand::DumpSampleCallchain(const SampleRecord& sr) {
                     s.dso->Path().c_str(), s.vaddr_in_file);
       printf("%s\n", output.c_str());
     }
+    fflush(stdout);
   }
 }
 
diff --git a/simpleperf/event_selection_set.cpp b/simpleperf/event_selection_set.cpp
index b92f1005..2ef634b4 100644
--- a/simpleperf/event_selection_set.cpp
+++ b/simpleperf/event_selection_set.cpp
@@ -488,6 +488,15 @@ bool EventSelectionSet::RecordNotExecutableMaps() const {
   return groups_[0][0].event_attr.mmap_data == 1;
 }
 
+void EventSelectionSet::WakeupPerSample() {
+  for (auto& group : groups_) {
+    for (auto& selection : group) {
+      selection.event_attr.watermark = 0;
+      selection.event_attr.wakeup_events = 1;
+    }
+  }
+}
+
 bool EventSelectionSet::SetTracepointFilter(const std::string& filter) {
   // 1. Find the tracepoint event to set filter.
   EventSelection* selection = nullptr;
diff --git a/simpleperf/event_selection_set.h b/simpleperf/event_selection_set.h
index c2e2408f..7d84b620 100644
--- a/simpleperf/event_selection_set.h
+++ b/simpleperf/event_selection_set.h
@@ -128,6 +128,7 @@ class EventSelectionSet {
   bool NeedKernelSymbol() const;
   void SetRecordNotExecutableMaps(bool record);
   bool RecordNotExecutableMaps() const;
+  void WakeupPerSample();
   void SetAddrFilters(std::vector<AddrFilter>&& filters) { addr_filters_ = std::move(filters); }
   bool SetTracepointFilter(const std::string& filter);