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src/share/vm/memory/barrierSet.hpp@7b0e9cba0307 (annotated)

src/share/vm/memory/barrierSet.hpp

Wed, 13 Jan 2010 15:26:39 -0800

author

ysr

date

Wed, 13 Jan 2010 15:26:39 -0800

changeset 1601

7b0e9cba0307

parent 1526

6aa7255741f3

child 1680

6484c4ee11cb

permissions

-rw-r--r--

6896647: card marks can be deferred too long
Summary: Deferred card marks are now flushed during the gc prologue. Parallel[Scavege,OldGC] and SerialGC no longer defer card marks generated by COMPILER2 as a result of ReduceInitialCardMarks. For these cases, introduced a diagnostic option to defer the card marks, only for the purposes of testing and diagnostics. CMS and G1 continue to defer card marks. Potential performance concern related to single-threaded flushing of deferred card marks in the gc prologue will be addressed in the future.
Reviewed-by: never, johnc

duke@435	1	/*
xdono@631	2	* Copyright 2000-2008 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	// This class provides the interface between a barrier implementation and
duke@435	26	// the rest of the system.
duke@435	27
duke@435	28	class BarrierSet: public CHeapObj {
duke@435	29	friend class VMStructs;
duke@435	30	public:
duke@435	31	enum Name {
duke@435	32	ModRef,
duke@435	33	CardTableModRef,
duke@435	34	CardTableExtension,
ysr@777	35	G1SATBCT,
ysr@777	36	G1SATBCTLogging,
duke@435	37	Other,
duke@435	38	Uninit
duke@435	39	};
duke@435	40
duke@435	41	protected:
duke@435	42	int _max_covered_regions;
duke@435	43	Name _kind;
duke@435	44
duke@435	45	public:
duke@435	46
ysr@777	47	BarrierSet() { _kind = Uninit; }
duke@435	48	// To get around prohibition on RTTI.
ysr@777	49	BarrierSet::Name kind() { return _kind; }
duke@435	50	virtual bool is_a(BarrierSet::Name bsn) = 0;
duke@435	51
duke@435	52	// These operations indicate what kind of barriers the BarrierSet has.
duke@435	53	virtual bool has_read_ref_barrier() = 0;
duke@435	54	virtual bool has_read_prim_barrier() = 0;
duke@435	55	virtual bool has_write_ref_barrier() = 0;
ysr@777	56	virtual bool has_write_ref_pre_barrier() = 0;
duke@435	57	virtual bool has_write_prim_barrier() = 0;
duke@435	58
duke@435	59	// These functions indicate whether a particular access of the given
duke@435	60	// kinds requires a barrier.
coleenp@548	61	virtual bool read_ref_needs_barrier(void* field) = 0;
duke@435	62	virtual bool read_prim_needs_barrier(HeapWord* field, size_t bytes) = 0;
coleenp@548	63	virtual bool write_ref_needs_barrier(void* field, oop new_val) = 0;
ysr@777	64	virtual bool write_prim_needs_barrier(HeapWord* field, size_t bytes,
ysr@777	65	juint val1, juint val2) = 0;
duke@435	66
duke@435	67	// The first four operations provide a direct implementation of the
duke@435	68	// barrier set. An interpreter loop, for example, could call these
duke@435	69	// directly, as appropriate.
duke@435	70
duke@435	71	// Invoke the barrier, if any, necessary when reading the given ref field.
coleenp@548	72	virtual void read_ref_field(void* field) = 0;
duke@435	73
duke@435	74	// Invoke the barrier, if any, necessary when reading the given primitive
duke@435	75	// "field" of "bytes" bytes in "obj".
duke@435	76	virtual void read_prim_field(HeapWord* field, size_t bytes) = 0;
duke@435	77
duke@435	78	// Invoke the barrier, if any, necessary when writing "new_val" into the
duke@435	79	// ref field at "offset" in "obj".
duke@435	80	// (For efficiency reasons, this operation is specialized for certain
duke@435	81	// barrier types. Semantically, it should be thought of as a call to the
duke@435	82	// virtual "_work" function below, which must implement the barrier.)
ysr@777	83	// First the pre-write versions...
ysr@1280	84	template <class T> inline void write_ref_field_pre(T* field, oop new_val);
ysr@1280	85	private:
ysr@1280	86	// Keep this private so as to catch violations at build time.
ysr@1280	87	virtual void write_ref_field_pre_work( void* field, oop new_val) { guarantee(false, "Not needed"); };
ysr@777	88	protected:
ysr@1280	89	virtual void write_ref_field_pre_work( oop* field, oop new_val) {};
ysr@1280	90	virtual void write_ref_field_pre_work(narrowOop* field, oop new_val) {};
ysr@777	91	public:
ysr@777	92
ysr@777	93	// ...then the post-write version.
coleenp@548	94	inline void write_ref_field(void* field, oop new_val);
duke@435	95	protected:
coleenp@548	96	virtual void write_ref_field_work(void* field, oop new_val) = 0;
duke@435	97	public:
duke@435	98
duke@435	99	// Invoke the barrier, if any, necessary when writing the "bytes"-byte
duke@435	100	// value(s) "val1" (and "val2") into the primitive "field".
duke@435	101	virtual void write_prim_field(HeapWord* field, size_t bytes,
duke@435	102	juint val1, juint val2) = 0;
duke@435	103
duke@435	104	// Operations on arrays, or general regions (e.g., for "clone") may be
duke@435	105	// optimized by some barriers.
duke@435	106
duke@435	107	// The first six operations tell whether such an optimization exists for
duke@435	108	// the particular barrier.
duke@435	109	virtual bool has_read_ref_array_opt() = 0;
duke@435	110	virtual bool has_read_prim_array_opt() = 0;
ysr@777	111	virtual bool has_write_ref_array_pre_opt() { return true; }
duke@435	112	virtual bool has_write_ref_array_opt() = 0;
duke@435	113	virtual bool has_write_prim_array_opt() = 0;
duke@435	114
duke@435	115	virtual bool has_read_region_opt() = 0;
duke@435	116	virtual bool has_write_region_opt() = 0;
duke@435	117
duke@435	118	// These operations should assert false unless the correponding operation
duke@435	119	// above returns true. Otherwise, they should perform an appropriate
duke@435	120	// barrier for an array whose elements are all in the given memory region.
duke@435	121	virtual void read_ref_array(MemRegion mr) = 0;
duke@435	122	virtual void read_prim_array(MemRegion mr) = 0;
duke@435	123
ysr@1526	124	// Below length is the # array elements being written
ysr@1280	125	virtual void write_ref_array_pre( oop* dst, int length) {}
ysr@1280	126	virtual void write_ref_array_pre(narrowOop* dst, int length) {}
ysr@1526	127	// Below MemRegion mr is expected to be HeapWord-aligned
duke@435	128	inline void write_ref_array(MemRegion mr);
ysr@1526	129	// Below count is the # array elements being written, starting
ysr@1526	130	// at the address "start", which may not necessarily be HeapWord-aligned
ysr@1526	131	inline void write_ref_array(HeapWord* start, size_t count);
ysr@777	132
ysr@1526	133	// Static versions, suitable for calling from generated code;
ysr@1526	134	// count is # array elements being written, starting with "start",
ysr@1526	135	// which may not necessarily be HeapWord-aligned.
ysr@777	136	static void static_write_ref_array_pre(HeapWord* start, size_t count);
ysr@777	137	static void static_write_ref_array_post(HeapWord* start, size_t count);
ysr@777	138
duke@435	139	protected:
duke@435	140	virtual void write_ref_array_work(MemRegion mr) = 0;
duke@435	141	public:
duke@435	142	virtual void write_prim_array(MemRegion mr) = 0;
duke@435	143
duke@435	144	virtual void read_region(MemRegion mr) = 0;
duke@435	145
duke@435	146	// (For efficiency reasons, this operation is specialized for certain
duke@435	147	// barrier types. Semantically, it should be thought of as a call to the
duke@435	148	// virtual "_work" function below, which must implement the barrier.)
duke@435	149	inline void write_region(MemRegion mr);
duke@435	150	protected:
duke@435	151	virtual void write_region_work(MemRegion mr) = 0;
duke@435	152	public:
duke@435	153
duke@435	154	// Some barrier sets create tables whose elements correspond to parts of
duke@435	155	// the heap; the CardTableModRefBS is an example. Such barrier sets will
duke@435	156	// normally reserve space for such tables, and commit parts of the table
duke@435	157	// "covering" parts of the heap that are committed. The constructor is
duke@435	158	// passed the maximum number of independently committable subregions to
duke@435	159	// be covered, and the "resize_covoered_region" function allows the
duke@435	160	// sub-parts of the heap to inform the barrier set of changes of their
duke@435	161	// sizes.
duke@435	162	BarrierSet(int max_covered_regions) :
duke@435	163	_max_covered_regions(max_covered_regions) {}
duke@435	164
duke@435	165	// Inform the BarrierSet that the the covered heap region that starts
duke@435	166	// with "base" has been changed to have the given size (possibly from 0,
duke@435	167	// for initialization.)
duke@435	168	virtual void resize_covered_region(MemRegion new_region) = 0;
duke@435	169
duke@435	170	// If the barrier set imposes any alignment restrictions on boundaries
duke@435	171	// within the heap, this function tells whether they are met.
duke@435	172	virtual bool is_aligned(HeapWord* addr) = 0;
duke@435	173
duke@435	174	};