--- a/hotspot/src/share/vm/memory/metaspace.cpp Thu Oct 17 06:29:58 2013 -0700
+++ b/hotspot/src/share/vm/memory/metaspace.cpp Tue Oct 15 13:56:46 2013 +0200
@@ -75,8 +75,7 @@
ClassSmallChunk = 256,
SmallChunk = 512,
ClassMediumChunk = 4 * K,
- MediumChunk = 8 * K,
- HumongousChunkGranularity = 8
+ MediumChunk = 8 * K
};
static ChunkIndex next_chunk_index(ChunkIndex i) {
@@ -92,6 +91,7 @@
// Manages the global free lists of chunks.
class ChunkManager : public CHeapObj<mtInternal> {
+ friend class TestVirtualSpaceNodeTest;
// Free list of chunks of different sizes.
// SpecializedChunk
@@ -257,6 +257,8 @@
// VirtualSpace
Metachunk* first_chunk() { return (Metachunk*) bottom(); }
+ // Committed but unused space in the virtual space
+ size_t free_words_in_vs() const;
public:
VirtualSpaceNode(size_t byte_size);
@@ -301,7 +303,6 @@
// used and capacity in this single entry in the list
size_t used_words_in_vs() const;
size_t capacity_words_in_vs() const;
- size_t free_words_in_vs() const;
bool initialize();
@@ -319,6 +320,13 @@
// in the node from any freelist.
void purge(ChunkManager* chunk_manager);
+ // If an allocation doesn't fit in the current node a new node is created.
+ // Allocate chunks out of the remaining committed space in this node
+ // to avoid wasting that memory.
+ // This always adds up because all the chunk sizes are multiples of
+ // the smallest chunk size.
+ void retire(ChunkManager* chunk_manager);
+
#ifdef ASSERT
// Debug support
void mangle();
@@ -461,6 +469,10 @@
// and is typically followed by the allocation of a chunk.
bool create_new_virtual_space(size_t vs_word_size);
+ // Chunk up the unused committed space in the current
+ // virtual space and add the chunks to the free list.
+ void retire_current_virtual_space();
+
public:
VirtualSpaceList(size_t word_size);
VirtualSpaceList(ReservedSpace rs);
@@ -624,10 +636,12 @@
bool is_class() { return _mdtype == Metaspace::ClassType; }
// Accessors
- size_t specialized_chunk_size() { return SpecializedChunk; }
- size_t small_chunk_size() { return (size_t) is_class() ? ClassSmallChunk : SmallChunk; }
- size_t medium_chunk_size() { return (size_t) is_class() ? ClassMediumChunk : MediumChunk; }
- size_t medium_chunk_bunch() { return medium_chunk_size() * MediumChunkMultiple; }
+ size_t specialized_chunk_size() { return (size_t) is_class() ? ClassSpecializedChunk : SpecializedChunk; }
+ size_t small_chunk_size() { return (size_t) is_class() ? ClassSmallChunk : SmallChunk; }
+ size_t medium_chunk_size() { return (size_t) is_class() ? ClassMediumChunk : MediumChunk; }
+ size_t medium_chunk_bunch() { return medium_chunk_size() * MediumChunkMultiple; }
+
+ size_t smallest_chunk_size() { return specialized_chunk_size(); }
size_t allocated_blocks_words() const { return _allocated_blocks_words; }
size_t allocated_blocks_bytes() const { return _allocated_blocks_words * BytesPerWord; }
@@ -1056,6 +1070,35 @@
#endif
}
+void VirtualSpaceList::retire_current_virtual_space() {
+ assert_lock_strong(SpaceManager::expand_lock());
+
+ VirtualSpaceNode* vsn = current_virtual_space();
+
+ ChunkManager* cm = is_class() ? Metaspace::chunk_manager_class() :
+ Metaspace::chunk_manager_metadata();
+
+ vsn->retire(cm);
+}
+
+void VirtualSpaceNode::retire(ChunkManager* chunk_manager) {
+ for (int i = (int)MediumIndex; i >= (int)ZeroIndex; --i) {
+ ChunkIndex index = (ChunkIndex)i;
+ size_t chunk_size = chunk_manager->free_chunks(index)->size();
+
+ while (free_words_in_vs() >= chunk_size) {
+ DEBUG_ONLY(verify_container_count();)
+ Metachunk* chunk = get_chunk_vs(chunk_size);
+ assert(chunk != NULL, "allocation should have been successful");
+
+ chunk_manager->return_chunks(index, chunk);
+ chunk_manager->inc_free_chunks_total(chunk_size);
+ DEBUG_ONLY(verify_container_count();)
+ }
+ }
+ assert(free_words_in_vs() == 0, "should be empty now");
+}
+
VirtualSpaceList::VirtualSpaceList(size_t word_size) :
_is_class(false),
_virtual_space_list(NULL),
@@ -1181,6 +1224,7 @@
if (vs_expanded) {
return true;
}
+ retire_current_virtual_space();
// Get another virtual space.
size_t grow_vs_words = MAX2((size_t)VirtualSpaceSize, preferred_words);
@@ -1902,12 +1946,12 @@
chunk_word_size = medium_chunk_size();
}
- // Might still need a humongous chunk. Enforce an
- // eight word granularity to facilitate reuse (some
- // wastage but better chance of reuse).
+ // Might still need a humongous chunk. Enforce
+ // humongous allocations sizes to be aligned up to
+ // the smallest chunk size.
size_t if_humongous_sized_chunk =
align_size_up(word_size + Metachunk::overhead(),
- HumongousChunkGranularity);
+ smallest_chunk_size());
chunk_word_size =
MAX2((size_t) chunk_word_size, if_humongous_sized_chunk);
@@ -2151,10 +2195,10 @@
}
assert(humongous_chunks->word_size() == (size_t)
align_size_up(humongous_chunks->word_size(),
- HumongousChunkGranularity),
+ smallest_chunk_size()),
err_msg("Humongous chunk size is wrong: word size " SIZE_FORMAT
" granularity %d",
- humongous_chunks->word_size(), HumongousChunkGranularity));
+ humongous_chunks->word_size(), smallest_chunk_size()));
Metachunk* next_humongous_chunks = humongous_chunks->next();
humongous_chunks->container()->dec_container_count();
chunk_manager()->humongous_dictionary()->return_chunk(humongous_chunks);
@@ -3494,4 +3538,94 @@
TestMetaspaceAuxTest::test();
}
+class TestVirtualSpaceNodeTest {
+ static void chunk_up(size_t words_left, size_t& num_medium_chunks,
+ size_t& num_small_chunks,
+ size_t& num_specialized_chunks) {
+ num_medium_chunks = words_left / MediumChunk;
+ words_left = words_left % MediumChunk;
+
+ num_small_chunks = words_left / SmallChunk;
+ words_left = words_left % SmallChunk;
+ // how many specialized chunks can we get?
+ num_specialized_chunks = words_left / SpecializedChunk;
+ assert(words_left % SpecializedChunk == 0, "should be nothing left");
+ }
+
+ public:
+ static void test() {
+ MutexLockerEx ml(SpaceManager::expand_lock(), Mutex::_no_safepoint_check_flag);
+ const size_t vsn_test_size_words = MediumChunk * 4;
+ const size_t vsn_test_size_bytes = vsn_test_size_words * BytesPerWord;
+
+ // The chunk sizes must be multiples of eachother, or this will fail
+ STATIC_ASSERT(MediumChunk % SmallChunk == 0);
+ STATIC_ASSERT(SmallChunk % SpecializedChunk == 0);
+
+ { // No committed memory in VSN
+ ChunkManager cm(SpecializedChunk, SmallChunk, MediumChunk);
+ VirtualSpaceNode vsn(vsn_test_size_bytes);
+ vsn.initialize();
+ vsn.retire(&cm);
+ assert(cm.sum_free_chunks_count() == 0, "did not commit any memory in the VSN");
+ }
+
+ { // All of VSN is committed, half is used by chunks
+ ChunkManager cm(SpecializedChunk, SmallChunk, MediumChunk);
+ VirtualSpaceNode vsn(vsn_test_size_bytes);
+ vsn.initialize();
+ vsn.expand_by(vsn_test_size_words, vsn_test_size_words);
+ vsn.get_chunk_vs(MediumChunk);
+ vsn.get_chunk_vs(MediumChunk);
+ vsn.retire(&cm);
+ assert(cm.sum_free_chunks_count() == 2, "should have been memory left for 2 medium chunks");
+ assert(cm.sum_free_chunks() == 2*MediumChunk, "sizes should add up");
+ }
+
+ { // 4 pages of VSN is committed, some is used by chunks
+ ChunkManager cm(SpecializedChunk, SmallChunk, MediumChunk);
+ VirtualSpaceNode vsn(vsn_test_size_bytes);
+ const size_t page_chunks = 4 * (size_t)os::vm_page_size() / BytesPerWord;
+ assert(page_chunks < MediumChunk, "Test expects medium chunks to be at least 4*page_size");
+ vsn.initialize();
+ vsn.expand_by(page_chunks, page_chunks);
+ vsn.get_chunk_vs(SmallChunk);
+ vsn.get_chunk_vs(SpecializedChunk);
+ vsn.retire(&cm);
+
+ // committed - used = words left to retire
+ const size_t words_left = page_chunks - SmallChunk - SpecializedChunk;
+
+ size_t num_medium_chunks, num_small_chunks, num_spec_chunks;
+ chunk_up(words_left, num_medium_chunks, num_small_chunks, num_spec_chunks);
+
+ assert(num_medium_chunks == 0, "should not get any medium chunks");
+ assert(cm.sum_free_chunks_count() == (num_small_chunks + num_spec_chunks), "should be space for 3 chunks");
+ assert(cm.sum_free_chunks() == words_left, "sizes should add up");
+ }
+
+ { // Half of VSN is committed, a humongous chunk is used
+ ChunkManager cm(SpecializedChunk, SmallChunk, MediumChunk);
+ VirtualSpaceNode vsn(vsn_test_size_bytes);
+ vsn.initialize();
+ vsn.expand_by(MediumChunk * 2, MediumChunk * 2);
+ vsn.get_chunk_vs(MediumChunk + SpecializedChunk); // Humongous chunks will be aligned up to MediumChunk + SpecializedChunk
+ vsn.retire(&cm);
+
+ const size_t words_left = MediumChunk * 2 - (MediumChunk + SpecializedChunk);
+ size_t num_medium_chunks, num_small_chunks, num_spec_chunks;
+ chunk_up(words_left, num_medium_chunks, num_small_chunks, num_spec_chunks);
+
+ assert(num_medium_chunks == 0, "should not get any medium chunks");
+ assert(cm.sum_free_chunks_count() == (num_small_chunks + num_spec_chunks), "should be space for 3 chunks");
+ assert(cm.sum_free_chunks() == words_left, "sizes should add up");
+ }
+
+ }
+};
+
+void TestVirtualSpaceNode_test() {
+ TestVirtualSpaceNodeTest::test();
+}
+
#endif