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src/hotspot/share/gc/shenandoah/heuristics/shenandoahHeuristics.cpp

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@@ -1,7 +1,8 @@
  /*
   * Copyright (c) 2018, 2020, Red Hat, Inc. All rights reserved.
+  * Copyright Amazon.com Inc. or its affiliates. All Rights Reserved.
   * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   *
   * This code is free software; you can redistribute it and/or modify it
   * under the terms of the GNU General Public License version 2 only, as
   * published by the Free Software Foundation.

@@ -22,38 +23,39 @@
   *
   */
  
  #include "precompiled.hpp"
  #include "gc/shared/gcCause.hpp"
- #include "gc/shenandoah/shenandoahCollectionSet.inline.hpp"
  #include "gc/shenandoah/shenandoahCollectorPolicy.hpp"
- #include "gc/shenandoah/shenandoahHeap.inline.hpp"
  #include "gc/shenandoah/shenandoahHeapRegion.inline.hpp"
  #include "gc/shenandoah/shenandoahMarkingContext.inline.hpp"
  #include "gc/shenandoah/heuristics/shenandoahHeuristics.hpp"
  #include "logging/log.hpp"
  #include "logging/logTag.hpp"
  #include "runtime/globals_extension.hpp"
+ #include "utilities/quickSort.hpp"
  
+ // sort by decreasing garbage (so most garbage comes first)
  int ShenandoahHeuristics::compare_by_garbage(RegionData a, RegionData b) {
-   if (a._garbage > b._garbage)
+   if (a._u._garbage > b._u._garbage)
      return -1;
-   else if (a._garbage < b._garbage)
+   else if (a._u._garbage < b._u._garbage)
      return 1;
    else return 0;
  }
  
  ShenandoahHeuristics::ShenandoahHeuristics(ShenandoahSpaceInfo* space_info) :
    _space_info(space_info),
    _region_data(nullptr),
    _degenerated_cycles_in_a_row(0),
    _successful_cycles_in_a_row(0),
+   _guaranteed_gc_interval(0),
    _cycle_start(os::elapsedTime()),
    _last_cycle_end(0),
    _gc_times_learned(0),
    _gc_time_penalties(0),
-   _gc_time_history(new TruncatedSeq(10, ShenandoahAdaptiveDecayFactor)),
+   _gc_cycle_time_history(new TruncatedSeq(Moving_Average_Samples, ShenandoahAdaptiveDecayFactor)),
    _metaspace_oom()
  {
    // No unloading during concurrent mark? Communicate that to heuristics
    if (!ClassUnloadingWithConcurrentMark) {
      FLAG_SET_DEFAULT(ShenandoahUnloadClassesFrequency, 0);

@@ -68,11 +70,11 @@
  ShenandoahHeuristics::~ShenandoahHeuristics() {
    FREE_C_HEAP_ARRAY(RegionGarbage, _region_data);
  }
  
  void ShenandoahHeuristics::choose_collection_set(ShenandoahCollectionSet* collection_set) {
-   assert(collection_set->count() == 0, "Must be empty");
+   assert(collection_set->is_empty(), "Must be empty");
  
    ShenandoahHeap* heap = ShenandoahHeap::heap();
  
    // Check all pinned regions have updated status before choosing the collection set.
    heap->assert_pinned_region_status();

@@ -111,11 +113,11 @@
          immediate_garbage += garbage;
          region->make_trash_immediate();
        } else {
          // This is our candidate for later consideration.
          candidates[cand_idx]._region = region;
-         candidates[cand_idx]._garbage = garbage;
+         candidates[cand_idx]._u._garbage = garbage;
          cand_idx++;
        }
      } else if (region->is_humongous_start()) {
        // Reclaim humongous regions here, and count them as the immediate garbage
  #ifdef ASSERT

@@ -149,32 +151,37 @@
  
    size_t immediate_percent = (total_garbage == 0) ? 0 : (immediate_garbage * 100 / total_garbage);
  
    if (immediate_percent <= ShenandoahImmediateThreshold) {
      choose_collection_set_from_regiondata(collection_set, candidates, cand_idx, immediate_garbage + free);
+   } else {
+     // We are going to skip evacuation and update refs because we reclaimed
+     // sufficient amounts of immediate garbage.
+     heap->shenandoah_policy()->record_abbreviated_cycle();
    }
  
    size_t cset_percent = (total_garbage == 0) ? 0 : (collection_set->garbage() * 100 / total_garbage);
- 
    size_t collectable_garbage = collection_set->garbage() + immediate_garbage;
    size_t collectable_garbage_percent = (total_garbage == 0) ? 0 : (collectable_garbage * 100 / total_garbage);
  
    log_info(gc, ergo)("Collectable Garbage: " SIZE_FORMAT "%s (" SIZE_FORMAT "%%), "
-                      "Immediate: " SIZE_FORMAT "%s (" SIZE_FORMAT "%%), "
-                      "CSet: " SIZE_FORMAT "%s (" SIZE_FORMAT "%%)",
+                      "Immediate: " SIZE_FORMAT "%s (" SIZE_FORMAT "%%), " SIZE_FORMAT " regions, "
+                      "CSet: " SIZE_FORMAT "%s (" SIZE_FORMAT "%%), " SIZE_FORMAT " regions",
  
                       byte_size_in_proper_unit(collectable_garbage),
                       proper_unit_for_byte_size(collectable_garbage),
                       collectable_garbage_percent,
  
                       byte_size_in_proper_unit(immediate_garbage),
                       proper_unit_for_byte_size(immediate_garbage),
                       immediate_percent,
+                      immediate_regions,
  
                       byte_size_in_proper_unit(collection_set->garbage()),
                       proper_unit_for_byte_size(collection_set->garbage()),
-                      cset_percent);
+                      cset_percent,
+                      collection_set->count());
  }
  
  void ShenandoahHeuristics::record_cycle_start() {
    _cycle_start = os::elapsedTime();
  }

@@ -189,15 +196,15 @@
      // Some of vmTestbase/metaspace tests depend on following line to count GC cycles
      log_info(gc)("Trigger: %s", GCCause::to_string(GCCause::_metadata_GC_threshold));
      return true;
    }
  
-   if (ShenandoahGuaranteedGCInterval > 0) {
+   if (_guaranteed_gc_interval > 0) {
      double last_time_ms = (os::elapsedTime() - _last_cycle_end) * 1000;
-     if (last_time_ms > ShenandoahGuaranteedGCInterval) {
-       log_info(gc)("Trigger: Time since last GC (%.0f ms) is larger than guaranteed interval (" UINTX_FORMAT " ms)",
-                    last_time_ms, ShenandoahGuaranteedGCInterval);
+     if (last_time_ms > _guaranteed_gc_interval) {
+       log_info(gc)("Trigger (%s): Time since last GC (%.0f ms) is larger than guaranteed interval (" UINTX_FORMAT " ms)",
+                    _space_info->name(), last_time_ms, _guaranteed_gc_interval);
        return true;
      }
    }
  
    return false;

@@ -207,11 +214,11 @@
    return _degenerated_cycles_in_a_row <= ShenandoahFullGCThreshold;
  }
  
  void ShenandoahHeuristics::adjust_penalty(intx step) {
    assert(0 <= _gc_time_penalties && _gc_time_penalties <= 100,
-           "In range before adjustment: " INTX_FORMAT, _gc_time_penalties);
+          "In range before adjustment: " INTX_FORMAT, _gc_time_penalties);
  
    intx new_val = _gc_time_penalties + step;
    if (new_val < 0) {
      new_val = 0;
    }

@@ -219,21 +226,23 @@
      new_val = 100;
    }
    _gc_time_penalties = new_val;
  
    assert(0 <= _gc_time_penalties && _gc_time_penalties <= 100,
-           "In range after adjustment: " INTX_FORMAT, _gc_time_penalties);
+          "In range after adjustment: " INTX_FORMAT, _gc_time_penalties);
  }
  
- void ShenandoahHeuristics::record_success_concurrent() {
+ void ShenandoahHeuristics::record_success_concurrent(bool abbreviated) {
    _degenerated_cycles_in_a_row = 0;
    _successful_cycles_in_a_row++;
- 
-   _gc_time_history->add(time_since_last_gc());
    _gc_times_learned++;
  
    adjust_penalty(Concurrent_Adjust);
+ 
+   if (_gc_times_learned <= ShenandoahLearningSteps || !(abbreviated && ShenandoahAdaptiveIgnoreShortCycles)) {
+     _gc_cycle_time_history->add(elapsed_cycle_time());
+   }
  }
  
  void ShenandoahHeuristics::record_success_degenerated() {
    _degenerated_cycles_in_a_row++;
    _successful_cycles_in_a_row = 0;

@@ -284,8 +293,8 @@
  
  void ShenandoahHeuristics::initialize() {
    // Nothing to do by default.
  }
  
- double ShenandoahHeuristics::time_since_last_gc() const {
+ double ShenandoahHeuristics::elapsed_cycle_time() const {
    return os::elapsedTime() - _cycle_start;
  }
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