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8277542: G1: Move G1CardSetFreePool and related classes to separate f… 
…iles

Reviewed-by: ayang, tschatzl
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Hamlin Li committed Nov 23, 2021
1 parent f62b81c commit bb11c55
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Showing 4 changed files with 326 additions and 256 deletions.
163 changes: 1 addition & 162 deletions src/hotspot/share/gc/g1/g1CardSetMemory.cpp
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Expand Up @@ -24,11 +24,10 @@

#include "precompiled.hpp"

#include "gc/g1/g1CardSetContainers.inline.hpp"
#include "gc/g1/g1CardSetMemory.inline.hpp"
#include "gc/g1/g1SegmentedArray.inline.hpp"
#include "logging/log.hpp"
#include "runtime/atomic.hpp"
#include "utilities/formatBuffer.hpp"
#include "utilities/ostream.hpp"


Expand Down Expand Up @@ -142,166 +141,6 @@ void G1CardSetAllocator<Elem>::print(outputStream* os) {
mem_size());
}

G1CardSetMemoryStats::G1CardSetMemoryStats() {
clear();
}

void G1CardSetMemoryStats::clear() {
for (uint i = 0; i < num_pools(); i++) {
_num_mem_sizes[i] = 0;
_num_buffers[i] = 0;
}
}

void G1CardSetFreePool::update_unlink_processors(G1ReturnMemoryProcessorSet* unlink_processor) {
uint num_free_lists = _freelist_pool.num_free_lists();

for (uint i = 0; i < num_free_lists; i++) {
unlink_processor->at(i)->visit_free_list(_freelist_pool.free_list(i));
}
}

void G1CardSetFreePool::G1ReturnMemoryProcessor::visit_free_list(G1CardSetBufferList* source) {
assert(_source == nullptr, "already visited");
if (_return_to_vm_size > 0) {
_source = source;
} else {
assert(_source == nullptr, "must be");
}
if (source->mem_size() > _return_to_vm_size) {
_first = source->get_all(_num_unlinked, _unlinked_bytes);
} else {
assert(_first == nullptr, "must be");
}
// Above we were racing with other threads getting the contents of the free list,
// so while we might have been asked to return something to the OS initially,
// the free list might be empty anyway. In this case just reset internal values
// used for checking whether there is work available.
if (_first == nullptr) {
_source = nullptr;
_return_to_vm_size = 0;
}
}

bool G1CardSetFreePool::G1ReturnMemoryProcessor::return_to_vm(jlong deadline) {
assert(!finished_return_to_vm(), "already returned everything to the VM");
assert(_first != nullptr, "must have element to return");

size_t keep_size = 0;
size_t keep_num = 0;

G1CardSetBuffer* cur = _first;
G1CardSetBuffer* last = nullptr;

while (cur != nullptr && _return_to_vm_size > 0) {
size_t cur_size = cur->mem_size();
_return_to_vm_size -= MIN2(_return_to_vm_size, cur_size);

keep_size += cur_size;
keep_num++;

last = cur;
cur = cur->next();
// To ensure progress, perform the deadline check here.
if (os::elapsed_counter() > deadline) {
break;
}
}

assert(_first != nullptr, "must be");
assert(last != nullptr, "must be");

last->set_next(nullptr);

// Wait for any in-progress pops to avoid ABA for them.
GlobalCounter::write_synchronize();
_source->bulk_add(*_first, *last, keep_num, keep_size);
_first = cur;

log_trace(gc, task)("Card Set Free Memory: Returned to VM %zu buffers size %zu", keep_num, keep_size);

// _return_to_vm_size may be larger than what is available in the list at the
// time we actually get the list. I.e. the list and _return_to_vm_size may be
// inconsistent.
// So also check if we actually already at the end of the list for the exit
// condition.
if (_return_to_vm_size == 0 || _first == nullptr) {
_source = nullptr;
_return_to_vm_size = 0;
}
return _source != nullptr;
}

bool G1CardSetFreePool::G1ReturnMemoryProcessor::return_to_os(jlong deadline) {
assert(finished_return_to_vm(), "not finished returning to VM");
assert(!finished_return_to_os(), "already returned everything to the OS");

// Now delete the rest.
size_t num_delete = 0;
size_t mem_size_deleted = 0;

while (_first != nullptr) {
G1CardSetBuffer* next = _first->next();
num_delete++;
mem_size_deleted += _first->mem_size();
delete _first;
_first = next;

// To ensure progress, perform the deadline check here.
if (os::elapsed_counter() > deadline) {
break;
}
}

log_trace(gc, task)("Card Set Free Memory: Return to OS %zu buffers size %zu", num_delete, mem_size_deleted);

return _first != nullptr;
}

G1CardSetFreePool G1CardSetFreePool::_freelist_pool(G1CardSetConfiguration::num_mem_object_types());

G1CardSetFreePool::G1CardSetFreePool(uint num_free_lists) :
_num_free_lists(num_free_lists) {

_free_lists = NEW_C_HEAP_ARRAY(G1CardSetBufferList, _num_free_lists, mtGC);
for (uint i = 0; i < _num_free_lists; i++) {
new (&_free_lists[i]) G1CardSetBufferList();
}
}

G1CardSetFreePool::~G1CardSetFreePool() {
for (uint i = 0; i < _num_free_lists; i++) {
_free_lists[i].~G1CardSetBufferList();
}
FREE_C_HEAP_ARRAY(mtGC, _free_lists);
}

G1CardSetMemoryStats G1CardSetFreePool::memory_sizes() const {
G1CardSetMemoryStats free_list_stats;
assert(free_list_stats.num_pools() == num_free_lists(), "must be");
for (uint i = 0; i < num_free_lists(); i++) {
free_list_stats._num_mem_sizes[i] = _free_lists[i].mem_size();
free_list_stats._num_buffers[i] = _free_lists[i].num_buffers();
}
return free_list_stats;
}

size_t G1CardSetFreePool::mem_size() const {
size_t result = 0;
for (uint i = 0; i < _num_free_lists; i++) {
result += _free_lists[i].mem_size();
}
return result;
}

void G1CardSetFreePool::print_on(outputStream* out) {
out->print_cr(" Free Pool: size %zu", free_list_pool()->mem_size());
for (uint i = 0; i < _num_free_lists; i++) {
FormatBuffer<> fmt(" %s", G1CardSetConfiguration::mem_object_type_name_str(i));
_free_lists[i].print_on(out, fmt);
}
}

G1CardSetMemoryManager::G1CardSetMemoryManager(G1CardSetConfiguration* config,
G1CardSetFreePool* free_list_pool) : _config(config) {

Expand Down
95 changes: 1 addition & 94 deletions src/hotspot/share/gc/g1/g1CardSetMemory.hpp
View file
Expand Up @@ -27,8 +27,8 @@

#include "gc/g1/g1CardSet.hpp"
#include "gc/g1/g1CardSetContainers.hpp"
#include "gc/g1/g1CardSetContainers.inline.hpp"
#include "gc/g1/g1SegmentedArray.hpp"
#include "gc/g1/g1SegmentedArrayFreePool.hpp"
#include "memory/allocation.hpp"
#include "utilities/growableArray.hpp"
#include "utilities/lockFreeStack.hpp"
Expand Down Expand Up @@ -136,99 +136,6 @@ class G1CardSetAllocator {
void print(outputStream* os);
};

// Statistics for a fixed set of buffer lists. Contains the number of buffers and memory
// used for each. Note that statistics are typically not taken atomically so there
// can be inconsistencies. The user must be prepared for them.
class G1CardSetMemoryStats {
public:

size_t _num_mem_sizes[G1CardSetConfiguration::num_mem_object_types()];
size_t _num_buffers[G1CardSetConfiguration::num_mem_object_types()];

// Returns all-zero statistics.
G1CardSetMemoryStats();

void add(G1CardSetMemoryStats const other) {
STATIC_ASSERT(ARRAY_SIZE(_num_buffers) == ARRAY_SIZE(_num_mem_sizes));
for (uint i = 0; i < ARRAY_SIZE(_num_mem_sizes); i++) {
_num_mem_sizes[i] += other._num_mem_sizes[i];
_num_buffers[i] += other._num_buffers[i];
}
}

void clear();

uint num_pools() const { return G1CardSetConfiguration::num_mem_object_types(); }
};

// A set of free lists holding memory buffers for use by G1CardSetAllocators.
class G1CardSetFreePool {
// The global free pool.
static G1CardSetFreePool _freelist_pool;

const uint _num_free_lists;
G1CardSetBufferList* _free_lists;

public:
static G1CardSetFreePool* free_list_pool() { return &_freelist_pool; }
static G1CardSetMemoryStats free_list_sizes() { return _freelist_pool.memory_sizes(); }

class G1ReturnMemoryProcessor;
typedef GrowableArrayCHeap<G1ReturnMemoryProcessor*, mtGC> G1ReturnMemoryProcessorSet;

static void update_unlink_processors(G1ReturnMemoryProcessorSet* unlink_processors);

explicit G1CardSetFreePool(uint num_free_lists);
~G1CardSetFreePool();

G1CardSetBufferList* free_list(uint i) {
assert(i < _num_free_lists, "must be");
return &_free_lists[i];
}

uint num_free_lists() const { return _num_free_lists; }

G1CardSetMemoryStats memory_sizes() const;
size_t mem_size() const;

void print_on(outputStream* out);
};

// Data structure containing current in-progress state for returning memory to the
// operating system for a single G1CardSetBufferList.
class G1CardSetFreePool::G1ReturnMemoryProcessor : public CHeapObj<mtGC> {
G1CardSetBufferList* _source;
size_t _return_to_vm_size;

G1CardSetBuffer* _first;
size_t _unlinked_bytes;
size_t _num_unlinked;

public:
explicit G1ReturnMemoryProcessor(size_t return_to_vm) :
_source(nullptr), _return_to_vm_size(return_to_vm), _first(nullptr), _unlinked_bytes(0), _num_unlinked(0) {
}

// Updates the instance members about the given card set buffer list for the purpose
// of giving back memory. Only necessary members are updated, e.g. if there is
// nothing to return to the VM, do not set the source list.
void visit_free_list(G1CardSetBufferList* source);

bool finished_return_to_vm() const { return _return_to_vm_size == 0; }
bool finished_return_to_os() const { return _first == nullptr; }

// Returns memory to the VM until the given deadline expires. Returns true if
// there is no more work. Guarantees forward progress, i.e. at least one buffer
// has been processed after returning.
// return_to_vm() re-adds buffers to the respective free list.
bool return_to_vm(jlong deadline);
// Returns memory to the VM until the given deadline expires. Returns true if
// there is no more work. Guarantees forward progress, i.e. at least one buffer
// has been processed after returning.
// return_to_os() gives back buffers to the OS.
bool return_to_os(jlong deadline);
};

class G1CardSetMemoryManager : public CHeapObj<mtGCCardSet> {
G1CardSetConfiguration* _config;

Expand Down

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