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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/heuristics/shenandoahSpaceInfo.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"
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;
// Source of information about the memory space managed by this heuristic
ShenandoahSpaceInfo* _space_info;
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);
virtual void choose_collection_set_from_regiondata(ShenandoahCollectionSet* set,
RegionData* data, size_t data_size,
size_t free) = 0;
void adjust_penalty(intx step);
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:
+ static const uint Moving_Average_Samples = 10; // Number of samples to store in moving averages
+
typedef struct {
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
+ } _u;
} RegionData;
// 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);
+ // TODO: We need to enhance this API to give visibility to accompanying old-gen evacuation effort.
+ // In the case that the old-gen evacuation effort is small or zero, the young-gen heuristics
+ // should feel free to dedicate increased efforts to young-gen evacuation.
+
virtual void choose_collection_set_from_regiondata(ShenandoahCollectionSet* set,
RegionData* data, size_t data_size,
size_t free) = 0;
void adjust_penalty(intx step);
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();
virtual bool should_degenerate_cycle();
! virtual void record_success_concurrent();
virtual void record_success_degenerated();
virtual void record_success_full();
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 bool should_degenerate_cycle();
! virtual void record_success_concurrent(bool abbreviated);
virtual void record_success_degenerated();
virtual void record_success_full();
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 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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