simpleperf: Rotate the last cpu disabling ETM events

When using ETR, ETM data is flushed to the aux buffer of the last
cpu disabling ETM events. To avoid overflowing the aux buffer for
one cpu, rotate the last cpu disabling ETM events.

Bug: 336375740
Test: run simpleperf manually
Change-Id: I1b5f2b85935513a3485d84fe0b850b8223ad03b4

2 files changed, 30 insertions, 2 deletions

diff --git a/simpleperf/event_selection_set.cpp b/simpleperf/event_selection_set.cpp
index 6a1e5a9e..1a7cdef8 100644
--- a/simpleperf/event_selection_set.cpp
+++ b/simpleperf/event_selection_set.cpp
@@ -974,9 +974,34 @@ bool EventSelectionSet::DisableETMEvents() {
       if (!sel.event_type_modifier.event_type.IsEtmEvent()) {
         continue;
       }
+      // When using ETR, ETM data is flushed to the aux buffer of the last cpu disabling ETM events.
+      // To avoid overflowing the aux buffer for one cpu, rotate the last cpu disabling ETM events.
+      if (etm_event_cpus_.empty()) {
+        for (const auto& fd : sel.event_fds) {
+          etm_event_cpus_.insert(fd->Cpu());
+        }
+        if (etm_event_cpus_.empty()) {
+          continue;
+        }
+        etm_event_cpus_it_ = etm_event_cpus_.begin();
+      }
+      int last_disabled_cpu = *etm_event_cpus_it_;
+      if (++etm_event_cpus_it_ == etm_event_cpus_.end()) {
+        etm_event_cpus_it_ = etm_event_cpus_.begin();
+      }
+
       for (auto& fd : sel.event_fds) {
-        if (!fd->SetEnableEvent(false)) {
-          return false;
+        if (fd->Cpu() != last_disabled_cpu) {
+          if (!fd->SetEnableEvent(false)) {
+            return false;
+          }
+        }
+      }
+      for (auto& fd : sel.event_fds) {
+        if (fd->Cpu() == last_disabled_cpu) {
+          if (!fd->SetEnableEvent(false)) {
+            return false;
+          }
         }
       }
     }
diff --git a/simpleperf/event_selection_set.h b/simpleperf/event_selection_set.h
index 1b3d6b4e..a892d51e 100644
--- a/simpleperf/event_selection_set.h
+++ b/simpleperf/event_selection_set.h
@@ -235,6 +235,9 @@ class EventSelectionSet {
   std::optional<SampleRate> sample_rate_;
   std::optional<std::vector<int>> cpus_;
 
+  std::set<int> etm_event_cpus_;
+  std::set<int>::const_iterator etm_event_cpus_it_;
+
   DISALLOW_COPY_AND_ASSIGN(EventSelectionSet);
 };