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src/share/vm/gc_implementation/concurrentMarkSweep/freeBlockDictionary.hpp@c70a245cad3a (annotated)

src/share/vm/gc_implementation/concurrentMarkSweep/freeBlockDictionary.hpp

Fri, 09 May 2008 08:55:13 -0700

author

dcubed

date

Fri, 09 May 2008 08:55:13 -0700

changeset 587

c70a245cad3a

parent 435

a61af66fc99e

child 622

790e66e5fbac

permissions

-rw-r--r--

6670684: 4/5 SA command universe did not print out CMS space information
Summary: Forward port of Yumin's fix for 6670684 from HSX-11; Yumin verified the port was correct.
Reviewed-by: dcubed

duke@435	1	/*
duke@435	2	* Copyright 2001-2005 Sun Microsystems, Inc. All Rights Reserved.
duke@435	3	* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
duke@435	4	*
duke@435	5	* This code is free software; you can redistribute it and/or modify it
duke@435	6	* under the terms of the GNU General Public License version 2 only, as
duke@435	7	* published by the Free Software Foundation.
duke@435	8	*
duke@435	9	* This code is distributed in the hope that it will be useful, but WITHOUT
duke@435	10	* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
duke@435	11	* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
duke@435	12	* version 2 for more details (a copy is included in the LICENSE file that
duke@435	13	* accompanied this code).
duke@435	14	*
duke@435	15	* You should have received a copy of the GNU General Public License version
duke@435	16	* 2 along with this work; if not, write to the Free Software Foundation,
duke@435	17	* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
duke@435	18	*
duke@435	19	* Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
duke@435	20	* CA 95054 USA or visit www.sun.com if you need additional information or
duke@435	21	* have any questions.
duke@435	22	*
duke@435	23	*/
duke@435	24
duke@435	25	//
duke@435	26	// Free block maintenance for Concurrent Mark Sweep Generation
duke@435	27	//
duke@435	28	// The main data structure for free blocks are
duke@435	29	// . an indexed array of small free blocks, and
duke@435	30	// . a dictionary of large free blocks
duke@435	31	//
duke@435	32
duke@435	33	// No virtuals in FreeChunk (don't want any vtables).
duke@435	34
duke@435	35	// A FreeChunk is merely a chunk that can be in a doubly linked list
duke@435	36	// and has a size field. NOTE: FreeChunks are distinguished from allocated
duke@435	37	// objects in two ways (by the sweeper). The second word (prev) has the
duke@435	38	// LSB set to indicate a free chunk; allocated objects' klass() pointers
duke@435	39	// don't have their LSB set. The corresponding bit in the CMSBitMap is
duke@435	40	// set when the chunk is allocated. There are also blocks that "look free"
duke@435	41	// but are not part of the free list and should not be coalesced into larger
duke@435	42	// free blocks. These free blocks have their two LSB's set.
duke@435	43
duke@435	44	class FreeChunk VALUE_OBJ_CLASS_SPEC {
duke@435	45	friend class VMStructs;
duke@435	46	FreeChunk* _next;
duke@435	47	FreeChunk* _prev;
duke@435	48	size_t _size;
duke@435	49
duke@435	50	public:
duke@435	51	NOT_PRODUCT(static const size_t header_size();)
duke@435	52	// Returns "true" if the "wrd", which is required to be the second word
duke@435	53	// of a block, indicates that the block represents a free chunk.
duke@435	54	static bool secondWordIndicatesFreeChunk(intptr_t wrd) {
duke@435	55	return (wrd & 0x1) == 0x1;
duke@435	56	}
duke@435	57	bool isFree() const {
duke@435	58	return secondWordIndicatesFreeChunk((intptr_t)_prev);
duke@435	59	}
duke@435	60	bool cantCoalesce() const { return (((intptr_t)_prev) & 0x3) == 0x3; }
duke@435	61	FreeChunk* next() const { return _next; }
duke@435	62	FreeChunk* prev() const { return (FreeChunk*)(((intptr_t)_prev) & ~(0x3)); }
duke@435	63	debug_only(void* prev_addr() const { return (void*)&_prev; })
duke@435	64
duke@435	65	void linkAfter(FreeChunk* ptr) {
duke@435	66	linkNext(ptr);
duke@435	67	if (ptr != NULL) ptr->linkPrev(this);
duke@435	68	}
duke@435	69	void linkAfterNonNull(FreeChunk* ptr) {
duke@435	70	assert(ptr != NULL, "precondition violation");
duke@435	71	linkNext(ptr);
duke@435	72	ptr->linkPrev(this);
duke@435	73	}
duke@435	74	void linkNext(FreeChunk* ptr) { _next = ptr; }
duke@435	75	void linkPrev(FreeChunk* ptr) { _prev = (FreeChunk*)((intptr_t)ptr | 0x1); }
duke@435	76	void clearPrev() { _prev = NULL; }
duke@435	77	void clearNext() { _next = NULL; }
duke@435	78	void dontCoalesce() {
duke@435	79	// the block should be free
duke@435	80	assert(isFree(), "Should look like a free block");
duke@435	81	_prev = (FreeChunk*)(((intptr_t)_prev) | 0x2);
duke@435	82	}
duke@435	83	void markFree() { _prev = (FreeChunk*)((intptr_t)_prev | 0x1); }
duke@435	84	void markNotFree() { _prev = NULL; }
duke@435	85
duke@435	86	size_t size() const { return _size; }
duke@435	87	void setSize(size_t size) { _size = size; }
duke@435	88
duke@435	89	// For volatile reads:
duke@435	90	size_t* size_addr() { return &_size; }
duke@435	91
duke@435	92	// Return the address past the end of this chunk
duke@435	93	HeapWord* end() const { return ((HeapWord*) this) + _size; }
duke@435	94
duke@435	95	// debugging
duke@435	96	void verify() const PRODUCT_RETURN;
duke@435	97	void verifyList() const PRODUCT_RETURN;
duke@435	98	void mangleAllocated(size_t size) PRODUCT_RETURN;
duke@435	99	void mangleFreed(size_t size) PRODUCT_RETURN;
duke@435	100	};
duke@435	101
duke@435	102	// Alignment helpers etc.
duke@435	103	#define numQuanta(x,y) ((x+y-1)/y)
duke@435	104	enum AlignmentConstants {
duke@435	105	MinChunkSize = numQuanta(sizeof(FreeChunk), MinObjAlignmentInBytes) * MinObjAlignment
duke@435	106	};
duke@435	107
duke@435	108	// A FreeBlockDictionary is an abstract superclass that will allow
duke@435	109	// a number of alternative implementations in the future.
duke@435	110	class FreeBlockDictionary: public CHeapObj {
duke@435	111	public:
duke@435	112	enum Dither {
duke@435	113	atLeast,
duke@435	114	exactly,
duke@435	115	roughly
duke@435	116	};
duke@435	117	enum DictionaryChoice {
duke@435	118	dictionaryBinaryTree = 0,
duke@435	119	dictionarySplayTree = 1,
duke@435	120	dictionarySkipList = 2
duke@435	121	};
duke@435	122
duke@435	123	private:
duke@435	124	NOT_PRODUCT(Mutex* _lock;)
duke@435	125
duke@435	126	public:
duke@435	127	virtual void removeChunk(FreeChunk* fc) = 0;
duke@435	128	virtual FreeChunk* getChunk(size_t size, Dither dither = atLeast) = 0;
duke@435	129	virtual void returnChunk(FreeChunk* chunk) = 0;
duke@435	130	virtual size_t totalChunkSize(debug_only(const Mutex* lock)) const = 0;
duke@435	131	virtual size_t maxChunkSize() const = 0;
duke@435	132	virtual size_t minSize() const = 0;
duke@435	133	// Reset the dictionary to the initial conditions for a single
duke@435	134	// block.
duke@435	135	virtual void reset(HeapWord* addr, size_t size) = 0;
duke@435	136	virtual void reset() = 0;
duke@435	137
duke@435	138	virtual void dictCensusUpdate(size_t size, bool split, bool birth) = 0;
duke@435	139	virtual bool coalDictOverPopulated(size_t size) = 0;
duke@435	140	virtual void beginSweepDictCensus(double coalSurplusPercent,
duke@435	141	float sweep_current, float sweep_ewstimate) = 0;
duke@435	142	virtual void endSweepDictCensus(double splitSurplusPercent) = 0;
duke@435	143	virtual FreeChunk* findLargestDict() const = 0;
duke@435	144	// verify that the given chunk is in the dictionary.
duke@435	145	virtual bool verifyChunkInFreeLists(FreeChunk* tc) const = 0;
duke@435	146
duke@435	147	// Sigma_{all_free_blocks} (block_size^2)
duke@435	148	virtual double sum_of_squared_block_sizes() const = 0;
duke@435	149
duke@435	150	virtual FreeChunk* find_chunk_ends_at(HeapWord* target) const = 0;
duke@435	151	virtual void inc_totalSize(size_t v) = 0;
duke@435	152	virtual void dec_totalSize(size_t v) = 0;
duke@435	153
duke@435	154	NOT_PRODUCT (
duke@435	155	virtual size_t sumDictReturnedBytes() = 0;
duke@435	156	virtual void initializeDictReturnedBytes() = 0;
duke@435	157	virtual size_t totalCount() = 0;
duke@435	158	)
duke@435	159
duke@435	160	virtual void reportStatistics() const {
duke@435	161	gclog_or_tty->print("No statistics available");
duke@435	162	}
duke@435	163
duke@435	164	virtual void printDictCensus() const = 0;
duke@435	165
duke@435	166	virtual void verify() const = 0;
duke@435	167
duke@435	168	Mutex* par_lock() const PRODUCT_RETURN0;
duke@435	169	void set_par_lock(Mutex* lock) PRODUCT_RETURN;
duke@435	170	void verify_par_locked() const PRODUCT_RETURN;
duke@435	171	};