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8071277: G1: Merge commits and uncommits of contiguous memory

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Reviewed-by: iwalulya, ayang
This commit is contained in:
Thomas Schatzl 2025-09-29 10:05:45 +00:00
parent 75269fdb49
commit 08b677bba4
3 changed files with 65 additions and 43 deletions
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4
src/hotspot/share/gc/g1/g1NUMA.cpp
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@ -203,9 +203,7 @@ uint G1NUMA::index_for_region(G1HeapRegion* hr) const {
// * G1HeapRegion #: |-#0-||-#1-||-#2-||-#3-||-#4-||-#5-||-#6-||-#7-||-#8-||-#9-||#10-||#11-||#12-||#13-||#14-||#15-|
// * NUMA node #: |----#0----||----#1----||----#2----||----#3----||----#0----||----#1----||----#2----||----#3----|
void G1NUMA::request_memory_on_node(void* aligned_address, size_t size_in_bytes, uint region_index) {
if (!is_enabled()) {
return;
}
assert(is_enabled(), "must be, check before");
if (size_in_bytes == 0) {
return;

102
src/hotspot/share/gc/g1/g1RegionToSpaceMapper.cpp
View File

@ -96,13 +96,15 @@ class G1RegionsLargerThanCommitSizeMapper : public G1RegionToSpaceMapper {
const size_t start_page = (size_t)start_idx * _pages_per_region;
const size_t size_in_pages = num_regions * _pages_per_region;
bool zero_filled = _storage.commit(start_page, size_in_pages);
if (_memory_tag == mtJavaHeap) {
if (should_distribute_across_numa_nodes()) {
for (uint region_index = start_idx; region_index < start_idx + num_regions; region_index++ ) {
void* address = _storage.page_start(region_index * _pages_per_region);
size_t size_in_bytes = _storage.page_size() * _pages_per_region;
G1NUMA::numa()->request_memory_on_node(address, size_in_bytes, region_index);
}
}
if (AlwaysPreTouch) {
_storage.pretouch(start_page, size_in_pages, pretouch_workers);
}
@ -122,7 +124,7 @@ class G1RegionsLargerThanCommitSizeMapper : public G1RegionToSpaceMapper {
// G1RegionToSpaceMapper implementation where the region granularity is smaller
// than the commit granularity.
// Basically, the contents of one OS page span several regions.
// Basically, the contents of one OS page spans several regions.
class G1RegionsSmallerThanCommitSizeMapper : public G1RegionToSpaceMapper {
size_t _regions_per_page;
// Lock to prevent bitmap updates and the actual underlying
@ -148,13 +150,18 @@ class G1RegionsSmallerThanCommitSizeMapper : public G1RegionToSpaceMapper {
return _region_commit_map.find_first_set_bit(region, region_limit) != region_limit;
}
void numa_request_on_node(size_t page_idx) {
if (_memory_tag == mtJavaHeap) {
uint region = (uint)(page_idx * _regions_per_page);
void* address = _storage.page_start(page_idx);
size_t size_in_bytes = _storage.page_size();
G1NUMA::numa()->request_memory_on_node(address, size_in_bytes, region);
bool commit_pages(size_t start_page, size_t size_in_pages) {
bool result = _storage.commit(start_page, size_in_pages);
if (should_distribute_across_numa_nodes()) {
for (size_t page = start_page; page < start_page + size_in_pages; page++) {
uint region = checked_cast<uint>(page * _regions_per_page);
void* address = _storage.page_start(page);
size_t size_in_bytes = _storage.page_size();
G1NUMA::numa()->request_memory_on_node(address, size_in_bytes, region);
}
}
return result;
}
public:
@ -171,6 +178,21 @@ class G1RegionsSmallerThanCommitSizeMapper : public G1RegionToSpaceMapper {
guarantee((page_size * commit_factor) >= alloc_granularity, "allocation granularity smaller than commit granularity");
}
size_t find_first_uncommitted(size_t page, size_t end) {
assert(page < end, "must be");
while (page < end && is_page_committed(page)) {
page++;
}
return page;
}
size_t find_first_committed(size_t page, size_t end) {
while (page < end && !is_page_committed(page)) {
page++;
}
return MIN2(page, end);
}
virtual void commit_regions(uint start_idx, size_t num_regions, WorkerThreads* pretouch_workers) {
uint region_limit = (uint)(start_idx + num_regions);
assert(num_regions > 0, "Must commit at least one region");
@ -179,11 +201,11 @@ class G1RegionsSmallerThanCommitSizeMapper : public G1RegionToSpaceMapper {
size_t const NoPage = SIZE_MAX;
size_t first_committed = NoPage;
size_t num_committed = 0;
size_t first_newly_committed = NoPage;
size_t num_committed_pages = 0;
size_t start_page = region_idx_to_page_idx(start_idx);
size_t end_page = region_idx_to_page_idx(region_limit - 1);
size_t const start_page = region_idx_to_page_idx(start_idx);
size_t const end_page = region_idx_to_page_idx(region_limit - 1) + 1;
bool all_zero_filled = true;
@ -191,34 +213,27 @@ class G1RegionsSmallerThanCommitSizeMapper : public G1RegionToSpaceMapper {
// underlying OS page. See lock declaration for more details.
{
MutexLocker ml(&_lock, Mutex::_no_safepoint_check_flag);
for (size_t page = start_page; page <= end_page; page++) {
if (!is_page_committed(page)) {
// Page not committed.
if (num_committed == 0) {
first_committed = page;
}
num_committed++;
if (!_storage.commit(page, 1)) {
// Found dirty region during commit.
all_zero_filled = false;
}
size_t uncommitted_l = find_first_uncommitted(start_page, end_page);
size_t uncommitted_r = find_first_committed(uncommitted_l + 1, end_page);
// Move memory to correct NUMA node for the heap.
numa_request_on_node(page);
} else {
// Page already committed.
all_zero_filled = false;
}
first_newly_committed = uncommitted_l;
num_committed_pages = uncommitted_r - uncommitted_l;
if (num_committed_pages > 0 &&
!commit_pages(first_newly_committed, num_committed_pages)) {
all_zero_filled = false;
}
all_zero_filled &= (uncommitted_l == start_page) && (uncommitted_r == end_page);
// Update the commit map for the given range. Not using the par_set_range
// since updates to _region_commit_map for this mapper is protected by _lock.
_region_commit_map.set_range(start_idx, region_limit, BitMap::unknown_range);
}
if (AlwaysPreTouch && num_committed > 0) {
_storage.pretouch(first_committed, num_committed, pretouch_workers);
if (AlwaysPreTouch && num_committed_pages > 0) {
_storage.pretouch(first_newly_committed, num_committed_pages, pretouch_workers);
}
fire_on_commit(start_idx, num_regions, all_zero_filled);
@ -230,8 +245,8 @@ class G1RegionsSmallerThanCommitSizeMapper : public G1RegionToSpaceMapper {
assert(_region_commit_map.find_first_clear_bit(start_idx, region_limit) == region_limit,
"Should only be committed regions in the range [%u, %u)", start_idx, region_limit);
size_t start_page = region_idx_to_page_idx(start_idx);
size_t end_page = region_idx_to_page_idx(region_limit - 1);
size_t const start_page = region_idx_to_page_idx(start_idx);
size_t const end_page = region_idx_to_page_idx(region_limit - 1) + 1;
// Concurrent operations might operate on regions sharing the same
// underlying OS page. See lock declaration for more details.
@ -240,13 +255,16 @@ class G1RegionsSmallerThanCommitSizeMapper : public G1RegionToSpaceMapper {
// updates to _region_commit_map for this mapper is protected by _lock.
_region_commit_map.clear_range(start_idx, region_limit, BitMap::unknown_range);
for (size_t page = start_page; page <= end_page; page++) {
// We know all pages were committed before clearing the map. If the
// the page is still marked as committed after the clear we should
// not uncommit it.
if (!is_page_committed(page)) {
_storage.uncommit(page, 1);
}
// We know all pages were committed before clearing the map. If the
// the page is still marked as committed after the clear we should
// not uncommit it.
size_t uncommitted_l = find_first_uncommitted(start_page, end_page);
size_t uncommitted_r = find_first_committed(uncommitted_l + 1, end_page);
size_t num_uncommitted_pages_found = uncommitted_r - uncommitted_l;
if (num_uncommitted_pages_found > 0) {
_storage.uncommit(uncommitted_l, num_uncommitted_pages_found);
}
}
};
@ -257,6 +275,10 @@ void G1RegionToSpaceMapper::fire_on_commit(uint start_idx, size_t num_regions, b
}
}
bool G1RegionToSpaceMapper::should_distribute_across_numa_nodes() const {
return _memory_tag == mtJavaHeap && G1NUMA::numa()->is_enabled();
}
G1RegionToSpaceMapper* G1RegionToSpaceMapper::create_mapper(ReservedSpace rs,
size_t actual_size,
size_t page_size,

2
src/hotspot/share/gc/g1/g1RegionToSpaceMapper.hpp
View File

@ -58,6 +58,8 @@ class G1RegionToSpaceMapper : public CHeapObj<mtGC> {
G1RegionToSpaceMapper(ReservedSpace rs, size_t used_size, size_t page_size, size_t region_granularity, size_t commit_factor, MemTag mem_tag);
void fire_on_commit(uint start_idx, size_t num_regions, bool zero_filled);
bool should_distribute_across_numa_nodes() const;
public:
MemRegion reserved() { return _storage.reserved(); }