Mon, 06 Aug 2012 12:20:14 -0700
6818524: G1: use ergonomic resizing of PLABs
Summary: Employ PLABStats instances to record information about survivor and old PLABs, and use the recorded stats to adjust the sizes of survivor and old PLABS.
Reviewed-by: johnc, ysr
Contributed-by: Brandon Mitchell <brandon@twitter.com>
1 /*
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3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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7 * published by the Free Software Foundation.
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11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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13 * accompanied this code).
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23 */
25 #ifndef SHARE_VM_GC_IMPLEMENTATION_SHARED_MARKSWEEP_HPP
26 #define SHARE_VM_GC_IMPLEMENTATION_SHARED_MARKSWEEP_HPP
28 #include "gc_interface/collectedHeap.hpp"
29 #include "memory/universe.hpp"
30 #include "oops/markOop.hpp"
31 #include "oops/oop.hpp"
32 #include "runtime/timer.hpp"
33 #include "utilities/growableArray.hpp"
34 #include "utilities/stack.hpp"
35 #include "utilities/taskqueue.hpp"
37 class ReferenceProcessor;
38 class DataLayout;
40 // MarkSweep takes care of global mark-compact garbage collection for a
41 // GenCollectedHeap using a four-phase pointer forwarding algorithm. All
42 // generations are assumed to support marking; those that can also support
43 // compaction.
44 //
45 // Class unloading will only occur when a full gc is invoked.
47 // If VALIDATE_MARK_SWEEP is defined, the -XX:+ValidateMarkSweep flag will
48 // be operational, and will provide slow but comprehensive self-checks within
49 // the GC. This is not enabled by default in product or release builds,
50 // since the extra call to track_adjusted_pointer() in _adjust_pointer()
51 // would be too much overhead, and would disturb performance measurement.
52 // However, debug builds are sometimes way too slow to run GC tests!
53 #ifdef ASSERT
54 #define VALIDATE_MARK_SWEEP 1
55 #endif
56 #ifdef VALIDATE_MARK_SWEEP
57 #define VALIDATE_MARK_SWEEP_ONLY(code) code
58 #else
59 #define VALIDATE_MARK_SWEEP_ONLY(code)
60 #endif
62 // declared at end
63 class PreservedMark;
65 class MarkSweep : AllStatic {
66 //
67 // Inline closure decls
68 //
69 class FollowRootClosure: public OopsInGenClosure {
70 public:
71 virtual void do_oop(oop* p);
72 virtual void do_oop(narrowOop* p);
73 };
75 class MarkAndPushClosure: public OopClosure {
76 public:
77 virtual void do_oop(oop* p);
78 virtual void do_oop(narrowOop* p);
79 virtual const bool should_remember_mdo() const { return true; }
80 virtual void remember_mdo(DataLayout* p) { MarkSweep::revisit_mdo(p); }
81 };
83 class FollowStackClosure: public VoidClosure {
84 public:
85 virtual void do_void();
86 };
88 class AdjustPointerClosure: public OopsInGenClosure {
89 private:
90 bool _is_root;
91 public:
92 AdjustPointerClosure(bool is_root) : _is_root(is_root) {}
93 virtual void do_oop(oop* p);
94 virtual void do_oop(narrowOop* p);
95 };
97 // Used for java/lang/ref handling
98 class IsAliveClosure: public BoolObjectClosure {
99 public:
100 virtual void do_object(oop p);
101 virtual bool do_object_b(oop p);
102 };
104 class KeepAliveClosure: public OopClosure {
105 protected:
106 template <class T> void do_oop_work(T* p);
107 public:
108 virtual void do_oop(oop* p);
109 virtual void do_oop(narrowOop* p);
110 };
112 //
113 // Friend decls
114 //
115 friend class AdjustPointerClosure;
116 friend class KeepAliveClosure;
117 friend class VM_MarkSweep;
118 friend void marksweep_init();
120 //
121 // Vars
122 //
123 protected:
124 // Traversal stacks used during phase1
125 static Stack<oop, mtGC> _marking_stack;
126 static Stack<ObjArrayTask, mtGC> _objarray_stack;
127 // Stack for live klasses to revisit at end of marking phase
128 static Stack<Klass*, mtGC> _revisit_klass_stack;
129 // Set (stack) of MDO's to revisit at end of marking phase
130 static Stack<DataLayout*, mtGC> _revisit_mdo_stack;
132 // Space for storing/restoring mark word
133 static Stack<markOop, mtGC> _preserved_mark_stack;
134 static Stack<oop, mtGC> _preserved_oop_stack;
135 static size_t _preserved_count;
136 static size_t _preserved_count_max;
137 static PreservedMark* _preserved_marks;
139 // Reference processing (used in ...follow_contents)
140 static ReferenceProcessor* _ref_processor;
142 #ifdef VALIDATE_MARK_SWEEP
143 static GrowableArray<void*>* _root_refs_stack;
144 static GrowableArray<oop> * _live_oops;
145 static GrowableArray<oop> * _live_oops_moved_to;
146 static GrowableArray<size_t>* _live_oops_size;
147 static size_t _live_oops_index;
148 static size_t _live_oops_index_at_perm;
149 static GrowableArray<void*>* _other_refs_stack;
150 static GrowableArray<void*>* _adjusted_pointers;
151 static bool _pointer_tracking;
152 static bool _root_tracking;
154 // The following arrays are saved since the time of the last GC and
155 // assist in tracking down problems where someone has done an errant
156 // store into the heap, usually to an oop that wasn't properly
157 // handleized across a GC. If we crash or otherwise fail before the
158 // next GC, we can query these arrays to find out the object we had
159 // intended to do the store to (assuming it is still alive) and the
160 // offset within that object. Covered under RecordMarkSweepCompaction.
161 static GrowableArray<HeapWord*> * _cur_gc_live_oops;
162 static GrowableArray<HeapWord*> * _cur_gc_live_oops_moved_to;
163 static GrowableArray<size_t>* _cur_gc_live_oops_size;
164 static GrowableArray<HeapWord*> * _last_gc_live_oops;
165 static GrowableArray<HeapWord*> * _last_gc_live_oops_moved_to;
166 static GrowableArray<size_t>* _last_gc_live_oops_size;
167 #endif
169 // Non public closures
170 static IsAliveClosure is_alive;
171 static KeepAliveClosure keep_alive;
173 // Class unloading. Update subklass/sibling/implementor links at end of marking phase.
174 static void follow_weak_klass_links();
176 // Class unloading. Clear weak refs in MDO's (ProfileData)
177 // at the end of the marking phase.
178 static void follow_mdo_weak_refs();
180 // Debugging
181 static void trace(const char* msg) PRODUCT_RETURN;
183 public:
184 // Public closures
185 static FollowRootClosure follow_root_closure;
186 static CodeBlobToOopClosure follow_code_root_closure; // => follow_root_closure
187 static MarkAndPushClosure mark_and_push_closure;
188 static FollowStackClosure follow_stack_closure;
189 static AdjustPointerClosure adjust_root_pointer_closure;
190 static AdjustPointerClosure adjust_pointer_closure;
192 // Reference Processing
193 static ReferenceProcessor* const ref_processor() { return _ref_processor; }
195 // Call backs for marking
196 static void mark_object(oop obj);
197 // Mark pointer and follow contents. Empty marking stack afterwards.
198 template <class T> static inline void follow_root(T* p);
199 // Check mark and maybe push on marking stack
200 template <class T> static inline void mark_and_push(T* p);
201 static inline void push_objarray(oop obj, size_t index);
203 static void follow_stack(); // Empty marking stack.
205 static void preserve_mark(oop p, markOop mark);
206 // Save the mark word so it can be restored later
207 static void adjust_marks(); // Adjust the pointers in the preserved marks table
208 static void restore_marks(); // Restore the marks that we saved in preserve_mark
210 template <class T> static inline void adjust_pointer(T* p, bool isroot);
212 static void adjust_root_pointer(oop* p) { adjust_pointer(p, true); }
213 static void adjust_pointer(oop* p) { adjust_pointer(p, false); }
214 static void adjust_pointer(narrowOop* p) { adjust_pointer(p, false); }
216 #ifdef VALIDATE_MARK_SWEEP
217 static void track_adjusted_pointer(void* p, bool isroot);
218 static void check_adjust_pointer(void* p);
219 static void track_interior_pointers(oop obj);
220 static void check_interior_pointers();
222 static void reset_live_oop_tracking(bool at_perm);
223 static void register_live_oop(oop p, size_t size);
224 static void validate_live_oop(oop p, size_t size);
225 static void live_oop_moved_to(HeapWord* q, size_t size, HeapWord* compaction_top);
226 static void compaction_complete();
228 // Querying operation of RecordMarkSweepCompaction results.
229 // Finds and prints the current base oop and offset for a word
230 // within an oop that was live during the last GC. Helpful for
231 // tracking down heap stomps.
232 static void print_new_location_of_heap_address(HeapWord* q);
233 #endif
235 // Call backs for class unloading
236 // Update subklass/sibling/implementor links at end of marking.
237 static void revisit_weak_klass_link(Klass* k);
238 // For weak refs clearing in MDO's
239 static void revisit_mdo(DataLayout* p);
240 };
242 class PreservedMark VALUE_OBJ_CLASS_SPEC {
243 private:
244 oop _obj;
245 markOop _mark;
247 public:
248 void init(oop obj, markOop mark) {
249 _obj = obj;
250 _mark = mark;
251 }
253 void adjust_pointer() {
254 MarkSweep::adjust_pointer(&_obj);
255 }
257 void restore() {
258 _obj->set_mark(_mark);
259 }
260 };
262 #endif // SHARE_VM_GC_IMPLEMENTATION_SHARED_MARKSWEEP_HPP