--- a/src/hotspot/share/memory/metaspace/chunkManager.hpp Tue Sep 10 14:52:53 2019 +0800
+++ b/src/hotspot/share/memory/metaspace/chunkManager.hpp Tue Sep 10 09:24:05 2019 +0200
@@ -1,5 +1,6 @@
/*
- * Copyright (c) 2018, 2019, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2019, SAP SE. All rights reserved.
+ * Copyright (c) 2019, Oracle and/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
@@ -26,173 +27,137 @@
#define SHARE_MEMORY_METASPACE_CHUNKMANAGER_HPP
#include "memory/allocation.hpp"
-#include "memory/binaryTreeDictionary.hpp"
-#include "memory/freeList.hpp"
+#include "memory/metaspace/chunkLevel.hpp"
+#include "memory/metaspace/counter.hpp"
#include "memory/metaspace/metachunk.hpp"
-#include "memory/metaspace/metaspaceStatistics.hpp"
-#include "memory/metaspaceChunkFreeListSummary.hpp"
-#include "utilities/globalDefinitions.hpp"
-
-class ChunkManagerTestAccessor;
namespace metaspace {
-typedef class FreeList<Metachunk> ChunkList;
-typedef BinaryTreeDictionary<Metachunk, FreeList<Metachunk> > ChunkTreeDictionary;
-
-// Manages the global free lists of chunks.
-class ChunkManager : public CHeapObj<mtInternal> {
- friend class ::ChunkManagerTestAccessor;
+class VirtualSpaceList;
+class cm_stats_t;
- // Free list of chunks of different sizes.
- // SpecializedChunk
- // SmallChunk
- // MediumChunk
- ChunkList _free_chunks[NumberOfFreeLists];
+// class ChunkManager
+//
+// The ChunkManager has a central role. Callers request chunks from it.
+// It keeps the freelists for chunks. If the freelist is exhausted it
+// allocates new chunks from a connected VirtualSpaceList.
+//
+class ChunkManager : public CHeapObj<mtInternal> {
- // Whether or not this is the class chunkmanager.
- const bool _is_class;
+ // A chunk manager is connected to a virtual space list which is used
+ // to allocate new root chunks when no free chunks are found.
+ VirtualSpaceList* const _vslist;
- // Return non-humongous chunk list by its index.
- ChunkList* free_chunks(ChunkIndex index);
+ // Name
+ const char* const _name;
- // Returns non-humongous chunk list for the given chunk word size.
- ChunkList* find_free_chunks_list(size_t word_size);
-
- // HumongousChunk
- ChunkTreeDictionary _humongous_dictionary;
+ // Freelist
+ MetachunkListCluster _chunks;
- // Returns the humongous chunk dictionary.
- ChunkTreeDictionary* humongous_dictionary() { return &_humongous_dictionary; }
- const ChunkTreeDictionary* humongous_dictionary() const { return &_humongous_dictionary; }
+ // Returns true if this manager contains the given chunk. Slow (walks free list) and
+ // only needed for verifications.
+ DEBUG_ONLY(bool contains_chunk(Metachunk* c) const;)
- // Size, in metaspace words, of all chunks managed by this ChunkManager
- size_t _free_chunks_total;
- // Number of chunks in this ChunkManager
- size_t _free_chunks_count;
+ // Given a chunk we are about to handout to the caller, make sure it is committed
+ // according to constants::committed_words_on_fresh_chunks.
+ // May fail if we hit the commit limit.
+ static bool commit_chunk_before_handout(Metachunk* c);
- // Update counters after a chunk was added or removed removed.
- void account_for_added_chunk(const Metachunk* c);
- void account_for_removed_chunk(const Metachunk* c);
-
- // Given a pointer to a chunk, attempts to merge it with neighboring
- // free chunks to form a bigger chunk. Returns true if successful.
- bool attempt_to_coalesce_around_chunk(Metachunk* chunk, ChunkIndex target_chunk_type);
+ // Take a single chunk from the given freelist and adjust counters. Returns NULL
+ // if there is no fitting chunk for this level.
+ Metachunk* remove_first_chunk_at_level(chklvl_t l);
- // Helper for chunk merging:
- // Given an address range with 1-n chunks which are all supposed to be
- // free and hence currently managed by this ChunkManager, remove them
- // from this ChunkManager and mark them as invalid.
- // - This does not correct the occupancy map.
- // - This does not adjust the counters in ChunkManager.
- // - Does not adjust container count counter in containing VirtualSpaceNode.
- // Returns number of chunks removed.
- int remove_chunks_in_area(MetaWord* p, size_t word_size);
+ // Given a chunk which must be outside of a freelist and must be free, split it to
+ // meet a target level and return it. Splinters are added to the freelist.
+ Metachunk* split_chunk_and_add_splinters(Metachunk* c, chklvl_t target_level);
+
+ // Uncommit all chunks equal or below the given level.
+ void uncommit_free_chunks(chklvl_t max_level);
+
+public:
- // Helper for chunk splitting: given a target chunk size and a larger free chunk,
- // split up the larger chunk into n smaller chunks, at least one of which should be
- // the target chunk of target chunk size. The smaller chunks, including the target
- // chunk, are returned to the freelist. The pointer to the target chunk is returned.
- // Note that this chunk is supposed to be removed from the freelist right away.
- Metachunk* split_chunk(size_t target_chunk_word_size, Metachunk* chunk);
-
- public:
-
- ChunkManager(bool is_class);
+ // Creates a chunk manager with a given name (which is for debug purposes only)
+ // and an associated space list which will be used to request new chunks from
+ // (see get_chunk())
+ ChunkManager(const char* name, VirtualSpaceList* space_list);
- // Add or delete (return) a chunk to the global freelist.
- Metachunk* chunk_freelist_allocate(size_t word_size);
-
- // Map a size to a list index assuming that there are lists
- // for special, small, medium, and humongous chunks.
- ChunkIndex list_index(size_t size);
-
- // Map a given index to the chunk size.
- size_t size_by_index(ChunkIndex index) const;
-
- bool is_class() const { return _is_class; }
+ // Get a chunk and be smart about it.
+ // - 1) Attempt to find a free chunk of exactly the pref_level level
+ // - 2) Failing that, attempt to find a chunk smaller or equal the maximal level.
+ // - 3) Failing that, attempt to find a free chunk of larger size and split it.
+ // - 4) Failing that, attempt to allocate a new chunk from the connected virtual space.
+ // - Failing that, give up and return NULL.
+ // Note: this is not guaranteed to return a *committed* chunk. The chunk manager will
+ // attempt to commit the returned chunk according to constants::committed_words_on_fresh_chunks;
+ // but this may fail if we hit a commit limit. In that case, a partly uncommitted chunk
+ // will be returned, and the commit is attempted again when we allocate from the chunk's
+ // uncommitted area. See also Metachunk::allocate.
+ Metachunk* get_chunk(chklvl_t max_level, chklvl_t pref_level);
- // Convenience accessors.
- size_t medium_chunk_word_size() const { return size_by_index(MediumIndex); }
- size_t small_chunk_word_size() const { return size_by_index(SmallIndex); }
- size_t specialized_chunk_word_size() const { return size_by_index(SpecializedIndex); }
+ // Return a single chunk to the ChunkManager and adjust accounting. May merge chunk
+ // with neighbors.
+ // Happens after a Classloader was unloaded and releases its metaspace chunks.
+ // !! Notes:
+ // 1) After this method returns, c may not be valid anymore. Do not access the chunk after this function returns.
+ // 2) This function will not remove c from its current chunk list. This has to be done by the caller prior to
+ // calling this method.
+ void return_chunk(Metachunk* c);
- // Take a chunk from the ChunkManager. The chunk is expected to be in
- // the chunk manager (the freelist if non-humongous, the dictionary if
- // humongous).
- void remove_chunk(Metachunk* chunk);
-
- // Return a single chunk of type index to the ChunkManager.
- void return_single_chunk(Metachunk* chunk);
-
- // Add the simple linked list of chunks to the freelist of chunks
- // of type index.
- void return_chunk_list(Metachunk* chunk);
+ // Return a single chunk to the freelist and adjust accounting. No merge is attempted.
+ void return_chunk_simple(Metachunk* c);
- // Total of the space in the free chunks list
- size_t free_chunks_total_words() const { return _free_chunks_total; }
- size_t free_chunks_total_bytes() const { return free_chunks_total_words() * BytesPerWord; }
-
- // Number of chunks in the free chunks list
- size_t free_chunks_count() const { return _free_chunks_count; }
-
- // Remove from a list by size. Selects list based on size of chunk.
- Metachunk* free_chunks_get(size_t chunk_word_size);
+ // Given a chunk c, which must be "in use" and must not be a root chunk, attempt to
+ // enlarge it in place by claiming its trailing buddy.
+ //
+ // This will only work if c is the leader of the buddy pair and the trailing buddy is free.
+ //
+ // If successful, the follower chunk will be removed from the freelists, the leader chunk c will
+ // double in size (level decreased by one).
+ //
+ // On success, true is returned, false otherwise.
+ bool attempt_enlarge_chunk(Metachunk* c);
-#define index_bounds_check(index) \
- assert(is_valid_chunktype(index), "Bad index: %d", (int) index)
-
- size_t num_free_chunks(ChunkIndex index) const {
- index_bounds_check(index);
-
- if (index == HumongousIndex) {
- return _humongous_dictionary.total_free_blocks();
- }
+ // Attempt to reclaim free areas in metaspace wholesale:
+ // - first, attempt to purge nodes of the backing virtual space. This can only be successful
+ // if whole nodes are only containing free chunks, so it highly depends on fragmentation.
+ // - then, it will uncommit areas of free chunks according to the rules laid down in
+ // settings (see settings.hpp).
+ void wholesale_reclaim();
- ssize_t count = _free_chunks[index].count();
- return count == -1 ? 0 : (size_t) count;
- }
+ // Run verifications. slow=true: verify chunk-internal integrity too.
+ DEBUG_ONLY(void verify(bool slow) const;)
+ DEBUG_ONLY(void verify_locked(bool slow) const;)
- size_t size_free_chunks_in_bytes(ChunkIndex index) const {
- index_bounds_check(index);
+ // Returns the name of this chunk manager.
+ const char* name() const { return _name; }
- size_t word_size = 0;
- if (index == HumongousIndex) {
- word_size = _humongous_dictionary.total_size();
- } else {
- const size_t size_per_chunk_in_words = _free_chunks[index].size();
- word_size = size_per_chunk_in_words * num_free_chunks(index);
- }
+ // Returns total number of chunks
+ int total_num_chunks() const { return _chunks.total_num_chunks(); }
- return word_size * BytesPerWord;
- }
+ // Returns number of words in all free chunks.
+ size_t total_word_size() const { return _chunks.total_word_size(); }
+
+ // Update statistics.
+ void add_to_statistics(cm_stats_t* out) const;
- MetaspaceChunkFreeListSummary chunk_free_list_summary() const {
- return MetaspaceChunkFreeListSummary(num_free_chunks(SpecializedIndex),
- num_free_chunks(SmallIndex),
- num_free_chunks(MediumIndex),
- num_free_chunks(HumongousIndex),
- size_free_chunks_in_bytes(SpecializedIndex),
- size_free_chunks_in_bytes(SmallIndex),
- size_free_chunks_in_bytes(MediumIndex),
- size_free_chunks_in_bytes(HumongousIndex));
- }
+ void print_on(outputStream* st) const;
+ void print_on_locked(outputStream* st) const;
+
+private:
+
+ static ChunkManager* _chunkmanager_class;
+ static ChunkManager* _chunkmanager_nonclass;
-#ifdef ASSERT
- // Debug support
- // Verify free list integrity. slow=true: verify chunk-internal integrity too.
- void verify(bool slow) const;
- void locked_verify(bool slow) const;
-#endif
+public:
- void locked_print_free_chunks(outputStream* st);
+ static ChunkManager* chunkmanager_class() { return _chunkmanager_class; }
+ static ChunkManager* chunkmanager_nonclass() { return _chunkmanager_nonclass; }
- // Fill in current statistic values to the given statistics object.
- void collect_statistics(ChunkManagerStatistics* out) const;
+ static void set_chunkmanager_class(ChunkManager* cm);
+ static void set_chunkmanager_nonclass(ChunkManager* cm);
};
} // namespace metaspace
-
#endif // SHARE_MEMORY_METASPACE_CHUNKMANAGER_HPP