< prev index next > src/hotspot/share/gc/shenandoah/heuristics/shenandoahHeuristics.cpp
Print this page
/*
! * Copyright (c) 2018, 2020, Red Hat, Inc. 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.
/*
! * Copyright (c) 2018, 2021, Red Hat, Inc. 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.
*
*/
#include "precompiled.hpp"
#include "gc/shared/gcCause.hpp"
+ #include "gc/shenandoah/shenandoahAllocRequest.hpp"
#include "gc/shenandoah/shenandoahCollectionSet.inline.hpp"
#include "gc/shenandoah/shenandoahCollectorPolicy.hpp"
+ #include "gc/shenandoah/shenandoahGeneration.hpp"
#include "gc/shenandoah/shenandoahHeap.inline.hpp"
#include "gc/shenandoah/shenandoahHeapRegion.inline.hpp"
#include "gc/shenandoah/shenandoahMarkingContext.inline.hpp"
+ #include "gc/shenandoah/shenandoahOldGeneration.hpp"
+ #include "gc/shenandoah/shenandoahYoungGeneration.hpp"
#include "gc/shenandoah/heuristics/shenandoahHeuristics.hpp"
+ #include "gc/shenandoah/mode/shenandoahMode.hpp"
#include "logging/log.hpp"
#include "logging/logTag.hpp"
#include "runtime/globals_extension.hpp"
int ShenandoahHeuristics::compare_by_garbage(RegionData a, RegionData b) {
else if (a._garbage < b._garbage)
return 1;
else return 0;
}
! ShenandoahHeuristics::ShenandoahHeuristics() :
_region_data(NULL),
_degenerated_cycles_in_a_row(0),
_successful_cycles_in_a_row(0),
_cycle_start(os::elapsedTime()),
_last_cycle_end(0),
_gc_times_learned(0),
_gc_time_penalties(0),
_gc_time_history(new TruncatedSeq(10, ShenandoahAdaptiveDecayFactor)),
_metaspace_oom()
{
// No unloading during concurrent mark? Communicate that to heuristics
if (!ClassUnloadingWithConcurrentMark) {
FLAG_SET_DEFAULT(ShenandoahUnloadClassesFrequency, 0);
else if (a._garbage < b._garbage)
return 1;
else return 0;
}
! ShenandoahHeuristics::ShenandoahHeuristics(ShenandoahGeneration* generation) :
+ _generation(generation),
_region_data(NULL),
_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)),
+ _live_memory_last_cycle(0),
+ _live_memory_penultimate_cycle(0),
_metaspace_oom()
{
// No unloading during concurrent mark? Communicate that to heuristics
if (!ClassUnloadingWithConcurrentMark) {
FLAG_SET_DEFAULT(ShenandoahUnloadClassesFrequency, 0);
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");
ShenandoahHeap* heap = ShenandoahHeap::heap();
// Check all pinned regions have updated status before choosing the collection set.
heap->assert_pinned_region_status();
// Step 1. Build up the region candidates we care about, rejecting losers and accepting winners right away.
ShenandoahHeuristics::~ShenandoahHeuristics() {
FREE_C_HEAP_ARRAY(RegionGarbage, _region_data);
}
! size_t ShenandoahHeuristics::select_aged_regions(size_t old_available, size_t num_regions, bool preselected_regions[]) {
! ShenandoahHeap* heap = ShenandoahHeap::heap();
+ size_t old_consumed = 0;
+ if (heap->mode()->is_generational()) {
+ for (size_t i = 0; i < num_regions; i++) {
+ ShenandoahHeapRegion* region = heap->get_region(i);
+ if (in_generation(region) && !region->is_empty() && region->is_regular() && (region->age() >= InitialTenuringThreshold)) {
+ size_t promotion_need = (size_t) (region->get_live_data_bytes() * ShenandoahEvacWaste);
+ if (old_consumed + promotion_need < old_available) {
+ old_consumed += promotion_need;
+ preselected_regions[i] = true;
+ }
+ // Note that we keep going even if one region is excluded from selection. Subsequent regions may be selected
+ // if they have smaller live data.
+ }
+ }
+ }
+ return old_consumed;
+ }
+ void ShenandoahHeuristics::choose_collection_set(ShenandoahCollectionSet* collection_set, ShenandoahOldHeuristics* old_heuristics) {
ShenandoahHeap* heap = ShenandoahHeap::heap();
+ bool is_generational = heap->mode()->is_generational();
+
+ assert(collection_set->count() == 0, "Must be empty");
+ assert(_generation->generation_mode() != OLD, "Old GC invokes ShenandoahOldHeuristics::choose_collection_set()");
// Check all pinned regions have updated status before choosing the collection set.
heap->assert_pinned_region_status();
// Step 1. Build up the region candidates we care about, rejecting losers and accepting winners right away.
size_t immediate_garbage = 0;
size_t immediate_regions = 0;
size_t free = 0;
size_t free_regions = 0;
!
- ShenandoahMarkingContext* const ctx = heap->complete_marking_context();
for (size_t i = 0; i < num_regions; i++) {
ShenandoahHeapRegion* region = heap->get_region(i);
size_t garbage = region->garbage();
total_garbage += garbage;
-
if (region->is_empty()) {
free_regions++;
free += ShenandoahHeapRegion::region_size_bytes();
} else if (region->is_regular()) {
if (!region->has_live()) {
// We can recycle it right away and put it in the free set.
immediate_regions++;
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;
cand_idx++;
}
} else if (region->is_humongous_start()) {
// Reclaim humongous regions here, and count them as the immediate garbage
#ifdef ASSERT
bool reg_live = region->has_live();
! bool bm_live = ctx->is_marked(cast_to_oop(region->bottom()));
assert(reg_live == bm_live,
"Humongous liveness and marks should agree. Region live: %s; Bitmap live: %s; Region Live Words: " SIZE_FORMAT,
BOOL_TO_STR(reg_live), BOOL_TO_STR(bm_live), region->get_live_data_words());
#endif
if (!region->has_live()) {
heap->trash_humongous_region_at(region);
// Count only the start. Continuations would be counted on "trash" path
immediate_regions++;
immediate_garbage += garbage;
}
} else if (region->is_trash()) {
// Count in just trashed collection set, during coalesced CM-with-UR
immediate_regions++;
immediate_garbage += garbage;
}
}
// Step 2. Look back at garbage statistics, and decide if we want to collect anything,
// given the amount of immediately reclaimable garbage. If we do, figure out the collection set.
assert (immediate_garbage <= total_garbage,
"Cannot have more immediate garbage than total garbage: " SIZE_FORMAT "%s vs " SIZE_FORMAT "%s",
byte_size_in_proper_unit(immediate_garbage), proper_unit_for_byte_size(immediate_garbage),
byte_size_in_proper_unit(total_garbage), proper_unit_for_byte_size(total_garbage));
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);
}
! 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 "%%), "
size_t immediate_garbage = 0;
size_t immediate_regions = 0;
size_t free = 0;
size_t free_regions = 0;
! size_t live_memory = 0;
for (size_t i = 0; i < num_regions; i++) {
ShenandoahHeapRegion* region = heap->get_region(i);
+ if (!in_generation(region)) {
+ continue;
+ }
size_t garbage = region->garbage();
total_garbage += garbage;
if (region->is_empty()) {
free_regions++;
free += ShenandoahHeapRegion::region_size_bytes();
} else if (region->is_regular()) {
if (!region->has_live()) {
// We can recycle it right away and put it in the free set.
immediate_regions++;
immediate_garbage += garbage;
region->make_trash_immediate();
} else {
+ assert (_generation->generation_mode() != OLD, "OLD is handled elsewhere");
+ live_memory += region->get_live_data_bytes();
// This is our candidate for later consideration.
candidates[cand_idx]._region = region;
+ if (is_generational && collection_set->is_preselected(i)) {
+ // If region is preselected, we know mode()->is_generational() and region->age() >= InitialTenuringThreshold)
+ garbage = ShenandoahHeapRegion::region_size_bytes();
+ }
candidates[cand_idx]._garbage = garbage;
cand_idx++;
}
} else if (region->is_humongous_start()) {
+
// Reclaim humongous regions here, and count them as the immediate garbage
#ifdef ASSERT
bool reg_live = region->has_live();
! bool bm_live = heap->complete_marking_context()->is_marked(cast_to_oop(region->bottom()));
assert(reg_live == bm_live,
"Humongous liveness and marks should agree. Region live: %s; Bitmap live: %s; Region Live Words: " SIZE_FORMAT,
BOOL_TO_STR(reg_live), BOOL_TO_STR(bm_live), region->get_live_data_words());
#endif
if (!region->has_live()) {
heap->trash_humongous_region_at(region);
// Count only the start. Continuations would be counted on "trash" path
immediate_regions++;
immediate_garbage += garbage;
+ } else {
+ live_memory += region->get_live_data_bytes();
}
} else if (region->is_trash()) {
// Count in just trashed collection set, during coalesced CM-with-UR
immediate_regions++;
immediate_garbage += garbage;
+ } else { // region->is_humongous_cont() and !region->is_trash()
+ live_memory += region->get_live_data_bytes();
}
}
+ save_last_live_memory(live_memory);
+
// Step 2. Look back at garbage statistics, and decide if we want to collect anything,
// given the amount of immediately reclaimable garbage. If we do, figure out the collection set.
assert (immediate_garbage <= total_garbage,
"Cannot have more immediate garbage than total garbage: " SIZE_FORMAT "%s vs " SIZE_FORMAT "%s",
byte_size_in_proper_unit(immediate_garbage), proper_unit_for_byte_size(immediate_garbage),
byte_size_in_proper_unit(total_garbage), proper_unit_for_byte_size(total_garbage));
size_t immediate_percent = (total_garbage == 0) ? 0 : (immediate_garbage * 100 / total_garbage);
+ collection_set->set_immediate_trash(immediate_garbage);
if (immediate_percent <= ShenandoahImmediateThreshold) {
+ if (old_heuristics != NULL) {
+ old_heuristics->prime_collection_set(collection_set);
+ }
+ // else, this is global collection and doesn't need to prime_collection_set
+
+ // Add young-gen regions into the collection set. This is a virtual call, implemented differently by each
+ // of the heuristics subclasses.
choose_collection_set_from_regiondata(collection_set, candidates, cand_idx, immediate_garbage + free);
+ } else {
+ // we're going to skip evacuation and update refs because we reclaimed sufficient amounts of immediate garbage.
+ heap->shenandoah_policy()->record_abbreviated_cycle();
}
! if (collection_set->has_old_regions()) {
+ heap->shenandoah_policy()->record_mixed_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 "%%), "
immediate_percent,
byte_size_in_proper_unit(collection_set->garbage()),
proper_unit_for_byte_size(collection_set->garbage()),
cset_percent);
+
+ size_t bytes_evacuated = collection_set->get_bytes_reserved_for_evacuation();
+ log_info(gc, ergo)("Total Evacuation: " SIZE_FORMAT "%s",
+ byte_size_in_proper_unit(bytes_evacuated), proper_unit_for_byte_size(bytes_evacuated));
}
void ShenandoahHeuristics::record_cycle_start() {
_cycle_start = os::elapsedTime();
}
// 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) {
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);
return true;
}
}
return false;
// 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 (_guaranteed_gc_interval > 0) {
double last_time_ms = (os::elapsedTime() - _last_cycle_end) * 1000;
! 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)",
! _generation->name(), last_time_ms, _guaranteed_gc_interval);
return true;
}
}
return false;
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);
intx new_val = _gc_time_penalties + step;
if (new_val < 0) {
new_val = 0;
}
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);
intx new_val = _gc_time_penalties + step;
if (new_val < 0) {
new_val = 0;
}
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);
}
! void ShenandoahHeuristics::record_success_concurrent() {
_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);
}
void ShenandoahHeuristics::record_success_degenerated() {
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);
}
! void ShenandoahHeuristics::record_success_concurrent(bool abbreviated) {
_degenerated_cycles_in_a_row = 0;
_successful_cycles_in_a_row++;
! if (!(abbreviated && ShenandoahAdaptiveIgnoreShortCycles)) {
! _gc_time_history->add(time_since_last_gc());
+ _gc_times_learned++;
+ }
adjust_penalty(Concurrent_Adjust);
}
void ShenandoahHeuristics::record_success_degenerated() {
}
double ShenandoahHeuristics::time_since_last_gc() const {
return os::elapsedTime() - _cycle_start;
}
+
+ bool ShenandoahHeuristics::in_generation(ShenandoahHeapRegion* region) {
+ return ((_generation->generation_mode() == GLOBAL)
+ || (_generation->generation_mode() == YOUNG && region->affiliation() == YOUNG_GENERATION)
+ || (_generation->generation_mode() == OLD && region->affiliation() == OLD_GENERATION));
+ }
+
+ size_t ShenandoahHeuristics::min_free_threshold() {
+ size_t min_free_threshold =
+ _generation->generation_mode() == GenerationMode::OLD
+ ? ShenandoahOldMinFreeThreshold
+ : ShenandoahMinFreeThreshold;
+ return _generation->soft_max_capacity() / 100 * min_free_threshold;
+ }
+
+ void ShenandoahHeuristics::save_last_live_memory(size_t live_memory) {
+ _live_memory_penultimate_cycle = _live_memory_last_cycle;
+ _live_memory_last_cycle = live_memory;
+ }
+
+ size_t ShenandoahHeuristics::get_last_live_memory() {
+ return _live_memory_last_cycle;
+ }
+
+ size_t ShenandoahHeuristics::get_penultimate_live_memory() {
+ return _live_memory_penultimate_cycle;
+ }
< prev index next >