ART: add GC live ratio metrics to GC performance
Record average GC live ratio (copied bytes over allocated bytes in
form-space), and GC count for both minor and major ConcurrentCopy GC,
and print both if DumpGCPerformanceOnShutdown is set.
Test: Run art with -XX:DumpGCPerformanceOnShutdown on some benchmarks.
Bug: 112187497
Change-Id: I587f92d847b899c81bf7a6d7303f7b54527c6f33
diff --git a/runtime/gc/collector/concurrent_copying.cc b/runtime/gc/collector/concurrent_copying.cc
index 26a8d13..aba1c5a 100644
--- a/runtime/gc/collector/concurrent_copying.cc
+++ b/runtime/gc/collector/concurrent_copying.cc
@@ -93,6 +93,8 @@
from_space_num_bytes_at_first_pause_(0),
mark_stack_mode_(kMarkStackModeOff),
weak_ref_access_enabled_(true),
+ copied_live_bytes_ratio_sum_(0.f),
+ gc_count_(0),
young_gen_(young_gen),
skipped_blocks_lock_("concurrent copying bytes blocks lock", kMarkSweepMarkStackLock),
measure_read_barrier_slow_path_(measure_read_barrier_slow_path),
@@ -2038,6 +2040,11 @@
}
CHECK_LE(to_objects, from_objects);
CHECK_LE(to_bytes, from_bytes);
+ if (from_bytes > 0) {
+ copied_live_bytes_ratio_sum_ += static_cast<float>(to_bytes) / from_bytes;
+ gc_count_++;
+ }
+
// Cleared bytes and objects, populated by the call to RegionSpace::ClearFromSpace below.
uint64_t cleared_bytes;
uint64_t cleared_objects;
@@ -3204,6 +3211,15 @@
if (rb_slow_path_count_gc_total_ > 0) {
os << "GC slow path count " << rb_slow_path_count_gc_total_ << "\n";
}
+ float average_ratio = copied_live_bytes_ratio_sum_ / gc_count_;
+
+ if (young_gen_) {
+ os << "Average minor GC copied live bytes ratio "
+ << average_ratio << " over " << gc_count_ << " minor GCs\n";
+ } else {
+ os << "Average major GC copied live bytes ratio "
+ << average_ratio << " over " << gc_count_ << " major GCs\n";
+ }
os << "Cumulative bytes moved "
<< cumulative_bytes_moved_.load(std::memory_order_relaxed) << "\n";
os << "Cumulative objects moved "
diff --git a/runtime/gc/collector/concurrent_copying.h b/runtime/gc/collector/concurrent_copying.h
index 1a7464a..cd086c4 100644
--- a/runtime/gc/collector/concurrent_copying.h
+++ b/runtime/gc/collector/concurrent_copying.h
@@ -359,6 +359,18 @@
Atomic<uint64_t> cumulative_bytes_moved_;
Atomic<uint64_t> cumulative_objects_moved_;
+ // copied_live_bytes_ratio_sum_ and gc_count_ are read and written by CC per
+ // GC, in ReclaimPhase, and are read by DumpPerformanceInfo (potentially from
+ // another thread). However, at present, DumpPerformanceInfo is only called
+ // when the runtime shuts down, so no concurrent access.
+ // The sum of of all copied live bytes ratio (to_bytes/from_bytes)
+ float copied_live_bytes_ratio_sum_;
+ // The number of GC counts, used to calculate the average above. (It doesn't
+ // include GC where from_bytes is zero, IOW, from-space is empty, which is
+ // possible for minor GC if all allocated objects are in non-moving
+ // space.)
+ size_t gc_count_;
+
// Generational "sticky", only trace through dirty objects in region space.
const bool young_gen_;
// If true, the GC thread is done scanning marked objects on dirty and aged
