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/*
* Copyright (c) 2018, 2019, 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.
*/
#ifndef SHARE_GC_SHENANDOAH_HEURISTICS_SHENANDOAHHEURISTICS_HPP
#define SHARE_GC_SHENANDOAH_HEURISTICS_SHENANDOAHHEURISTICS_HPP
! #include "gc/shenandoah/shenandoahHeap.hpp"
- #include "gc/shenandoah/shenandoahPhaseTimings.hpp"
#include "gc/shenandoah/shenandoahSharedVariables.hpp"
#include "memory/allocation.hpp"
#include "runtime/globals_extension.hpp"
#define SHENANDOAH_ERGO_DISABLE_FLAG(name) \
do { \
if (FLAG_IS_DEFAULT(name) && (name)) { \
log_info(gc)("Heuristics ergonomically sets -XX:-" #name); \
*/
#ifndef SHARE_GC_SHENANDOAH_HEURISTICS_SHENANDOAHHEURISTICS_HPP
#define SHARE_GC_SHENANDOAH_HEURISTICS_SHENANDOAHHEURISTICS_HPP
! #include "gc/shenandoah/heuristics/shenandoahSpaceInfo.hpp"
#include "gc/shenandoah/shenandoahSharedVariables.hpp"
#include "memory/allocation.hpp"
#include "runtime/globals_extension.hpp"
+ #include "utilities/numberSeq.hpp"
#define SHENANDOAH_ERGO_DISABLE_FLAG(name) \
do { \
if (FLAG_IS_DEFAULT(name) && (name)) { \
log_info(gc)("Heuristics ergonomically sets -XX:-" #name); \
} while (0)
class ShenandoahCollectionSet;
class ShenandoahHeapRegion;
class ShenandoahHeuristics : public CHeapObj<mtGC> {
static const intx Concurrent_Adjust = -1; // recover from penalties
static const intx Degenerated_Penalty = 10; // how much to penalize average GC duration history on Degenerated GC
static const intx Full_Penalty = 20; // how much to penalize average GC duration history on Full GC
protected:
! typedef struct {
- ShenandoahHeapRegion* _region;
- size_t _garbage;
- } RegionData;
RegionData* _region_data;
! uint _degenerated_cycles_in_a_row;
- uint _successful_cycles_in_a_row;
double _cycle_start;
double _last_cycle_end;
size_t _gc_times_learned;
intx _gc_time_penalties;
! TruncatedSeq* _gc_time_history;
// There may be many threads that contend to set this flag
ShenandoahSharedFlag _metaspace_oom;
static int compare_by_garbage(RegionData a, RegionData b);
} while (0)
class ShenandoahCollectionSet;
class ShenandoahHeapRegion;
+ /*
+ * Shenandoah heuristics are primarily responsible for deciding when to start
+ * a collection cycle and choosing which regions will be evacuated during the
+ * cycle.
+ */
class ShenandoahHeuristics : public CHeapObj<mtGC> {
static const intx Concurrent_Adjust = -1; // recover from penalties
static const intx Degenerated_Penalty = 10; // how much to penalize average GC duration history on Degenerated GC
static const intx Full_Penalty = 20; // how much to penalize average GC duration history on Full GC
+ #ifdef ASSERT
+ enum UnionTag {
+ is_uninitialized, is_garbage, is_live_data
+ };
+ #endif
+
protected:
! static const uint Moving_Average_Samples = 10; // Number of samples to store in moving averages
+ class RegionData {
+ private:
+ ShenandoahHeapRegion* _region;
+ union {
+ size_t _garbage; // Not used by old-gen heuristics.
+ size_t _live_data; // Only used for old-gen heuristics, which prioritizes retention of _live_data over garbage reclaim
+ } _region_union;
+ #ifdef ASSERT
+ UnionTag _union_tag;
+ #endif
+ public:
+
+ #ifdef ASSERT
+ inline void clear() {
+ _union_tag = is_uninitialized;
+ }
+ #endif
+
+ inline void set_region_and_garbage(ShenandoahHeapRegion* region, size_t garbage) {
+ _region = region;
+ _region_union._garbage = garbage;
+ #ifdef ASSERT
+ _union_tag = is_garbage;
+ #endif
+ }
+
+ inline void set_region_and_livedata(ShenandoahHeapRegion* region, size_t live) {
+ _region = region;
+ _region_union._live_data = live;
+ #ifdef ASSERT
+ _union_tag = is_live_data;
+ #endif
+ }
+
+ inline ShenandoahHeapRegion* get_region() const {
+ #ifdef ASSERT
+ assert(_union_tag != is_uninitialized, "Cannot fetch region from uninialized RegionData");
+ #endif
+ return _region;
+ }
+
+ inline size_t get_garbage() const {
+ #ifdef ASSERT
+ assert(_union_tag == is_garbage, "Invalid union fetch");
+ #endif
+ return _region_union._garbage;
+ }
+
+ inline size_t get_livedata() const {
+ #ifdef ASSERT
+ assert(_union_tag == is_live_data, "Invalid union fetch");
+ #endif
+ return _region_union._live_data;
+ }
+ };
+
+ // Source of information about the memory space managed by this heuristic
+ ShenandoahSpaceInfo* _space_info;
+
+ // Depending on generation mode, region data represents the results of the relevant
+ // most recently completed marking pass:
+ // - in GLOBAL mode, global marking pass
+ // - in OLD mode, old-gen marking pass
+ // - in YOUNG mode, young-gen marking pass
+ //
+ // Note that there is some redundancy represented in region data because
+ // each instance is an array large enough to hold all regions. However,
+ // any region in young-gen is not in old-gen. And any time we are
+ // making use of the GLOBAL data, there is no need to maintain the
+ // YOUNG or OLD data. Consider this redundancy of data structure to
+ // have negligible cost unless proven otherwise.
RegionData* _region_data;
! size_t _guaranteed_gc_interval;
double _cycle_start;
double _last_cycle_end;
size_t _gc_times_learned;
intx _gc_time_penalties;
! TruncatedSeq* _gc_cycle_time_history;
// There may be many threads that contend to set this flag
ShenandoahSharedFlag _metaspace_oom;
static int compare_by_garbage(RegionData a, RegionData b);
size_t free) = 0;
void adjust_penalty(intx step);
public:
! ShenandoahHeuristics();
virtual ~ShenandoahHeuristics();
void record_metaspace_oom() { _metaspace_oom.set(); }
void clear_metaspace_oom() { _metaspace_oom.unset(); }
bool has_metaspace_oom() const { return _metaspace_oom.is_set(); }
virtual void record_cycle_start();
virtual void record_cycle_end();
virtual bool should_start_gc();
size_t free) = 0;
void adjust_penalty(intx step);
public:
! ShenandoahHeuristics(ShenandoahSpaceInfo* space_info);
virtual ~ShenandoahHeuristics();
void record_metaspace_oom() { _metaspace_oom.set(); }
void clear_metaspace_oom() { _metaspace_oom.unset(); }
bool has_metaspace_oom() const { return _metaspace_oom.is_set(); }
+ void set_guaranteed_gc_interval(size_t guaranteed_gc_interval) {
+ _guaranteed_gc_interval = guaranteed_gc_interval;
+ }
+
virtual void record_cycle_start();
virtual void record_cycle_end();
virtual bool should_start_gc();
virtual void record_requested_gc();
virtual void choose_collection_set(ShenandoahCollectionSet* collection_set);
virtual bool can_unload_classes();
virtual bool should_unload_classes();
virtual const char* name() = 0;
virtual bool is_diagnostic() = 0;
virtual bool is_experimental() = 0;
virtual void initialize();
! double time_since_last_gc() const;
};
#endif // SHARE_GC_SHENANDOAH_HEURISTICS_SHENANDOAHHEURISTICS_HPP
virtual void record_requested_gc();
virtual void choose_collection_set(ShenandoahCollectionSet* collection_set);
virtual bool can_unload_classes();
+
+ // This indicates whether or not the current cycle should unload classes.
+ // It does NOT indicate that a cycle should be started.
virtual bool should_unload_classes();
virtual const char* name() = 0;
virtual bool is_diagnostic() = 0;
virtual bool is_experimental() = 0;
virtual void initialize();
! double elapsed_cycle_time() const;
};
#endif // SHARE_GC_SHENANDOAH_HEURISTICS_SHENANDOAHHEURISTICS_HPP
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