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comparison src/share/vm/gc_implementation/g1/g1CollectedHeap.inline.hpp @ 1973:631f79e71e90

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6974966: G1: unnecessary direct-to-old allocations Summary: This change revamps the slow allocation path of G1. Improvements include the following: a) Allocations directly to old regions are now totally banned. G1 now only allows allocations out of young regions (with the only exception being humongous regions). b) The thread that allocates a new region (which is now guaranteed to be young) does not dirty all its cards. Each thread that successfully allocates out of a young region is now responsible for dirtying the cards that corresponding to the "block" that just got allocated. c) allocate_new_tlab() and mem_allocate() are now implemented differently and TLAB allocations are only done by allocate_new_tlab(). d) If a thread schedules an evacuation pause in order to satisfy an allocation request, it will perform the allocation at the end of the safepoint so that the thread that initiated the GC also gets "first pick" of any space made available by the GC. e) If a thread is unable to allocate a humongous object it will schedule an evacuation pause in case it reclaims enough regions so that the humongous allocation can be satisfied aftewards. f) The G1 policy is more careful to set the young list target length to be the survivor number +1. g) Lots of code tidy up, removal, refactoring to make future changes easier. Reviewed-by: johnc, ysr
author tonyp
date Tue, 24 Aug 2010 17:24:33 -0400
parents f95d63e2154a
children 016a3628c885
comparison
equal deleted inserted replaced
1972:f95d63e2154a 1973:631f79e71e90
25 #ifndef SHARE_VM_GC_IMPLEMENTATION_G1_G1COLLECTEDHEAP_INLINE_HPP 25 #ifndef SHARE_VM_GC_IMPLEMENTATION_G1_G1COLLECTEDHEAP_INLINE_HPP
26 #define SHARE_VM_GC_IMPLEMENTATION_G1_G1COLLECTEDHEAP_INLINE_HPP 26 #define SHARE_VM_GC_IMPLEMENTATION_G1_G1COLLECTEDHEAP_INLINE_HPP
27 27
28 #include "gc_implementation/g1/concurrentMark.hpp" 28 #include "gc_implementation/g1/concurrentMark.hpp"
29 #include "gc_implementation/g1/g1CollectedHeap.hpp" 29 #include "gc_implementation/g1/g1CollectedHeap.hpp"
30 #include "gc_implementation/g1/g1CollectorPolicy.hpp"
30 #include "gc_implementation/g1/heapRegionSeq.hpp" 31 #include "gc_implementation/g1/heapRegionSeq.hpp"
31 #include "utilities/taskqueue.hpp" 32 #include "utilities/taskqueue.hpp"
32 33
33 // Inline functions for G1CollectedHeap 34 // Inline functions for G1CollectedHeap
34 35
56 inline bool G1CollectedHeap::obj_in_cs(oop obj) { 57 inline bool G1CollectedHeap::obj_in_cs(oop obj) {
57 HeapRegion* r = _hrs->addr_to_region(obj); 58 HeapRegion* r = _hrs->addr_to_region(obj);
58 return r != NULL && r->in_collection_set(); 59 return r != NULL && r->in_collection_set();
59 } 60 }
60 61
61 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t word_size, 62 // See the comment in the .hpp file about the locking protocol and
62 bool permit_collection_pause) { 63 // assumptions of this method (and other related ones).
63 HeapWord* res = NULL; 64 inline HeapWord*
65 G1CollectedHeap::allocate_from_cur_alloc_region(HeapRegion* cur_alloc_region,
66 size_t word_size) {
67 assert_heap_locked_and_not_at_safepoint();
68 assert(cur_alloc_region != NULL, "pre-condition of the method");
69 assert(cur_alloc_region == _cur_alloc_region, "pre-condition of the method");
70 assert(cur_alloc_region->is_young(),
71 "we only support young current alloc regions");
72 assert(!isHumongous(word_size), "allocate_from_cur_alloc_region() "
73 "should not be used for humongous allocations");
74 assert(!cur_alloc_region->isHumongous(), "Catch a regression of this bug.");
64 75
65 assert( SafepointSynchronize::is_at_safepoint() || 76 assert(!cur_alloc_region->is_empty(),
66 Heap_lock->owned_by_self(), "pre-condition of the call" ); 77 err_msg("region ["PTR_FORMAT","PTR_FORMAT"] should not be empty",
78 cur_alloc_region->bottom(), cur_alloc_region->end()));
79 // This allocate method does BOT updates and we don't need them in
80 // the young generation. This will be fixed in the near future by
81 // CR 6994297.
82 HeapWord* result = cur_alloc_region->allocate(word_size);
83 if (result != NULL) {
84 assert(is_in(result), "result should be in the heap");
85 Heap_lock->unlock();
67 86
68 // All humongous allocation requests should go through the slow path in 87 // Do the dirtying after we release the Heap_lock.
69 // attempt_allocation_slow(). 88 dirty_young_block(result, word_size);
70 if (!isHumongous(word_size) && _cur_alloc_region != NULL) { 89 return result;
71 // If this allocation causes a region to become non empty, 90 }
72 // then we need to update our free_regions count.
73 91
74 if (_cur_alloc_region->is_empty()) { 92 assert_heap_locked();
75 res = _cur_alloc_region->allocate(word_size); 93 return NULL;
76 if (res != NULL) 94 }
77 _free_regions--; 95
78 } else { 96 // See the comment in the .hpp file about the locking protocol and
79 res = _cur_alloc_region->allocate(word_size); 97 // assumptions of this method (and other related ones).
98 inline HeapWord*
99 G1CollectedHeap::attempt_allocation(size_t word_size) {
100 assert_heap_locked_and_not_at_safepoint();
101 assert(!isHumongous(word_size), "attempt_allocation() should not be called "
102 "for humongous allocation requests");
103
104 HeapRegion* cur_alloc_region = _cur_alloc_region;
105 if (cur_alloc_region != NULL) {
106 HeapWord* result = allocate_from_cur_alloc_region(cur_alloc_region,
107 word_size);
108 if (result != NULL) {
109 assert_heap_not_locked();
110 return result;
80 } 111 }
81 112
82 if (res != NULL) { 113 assert_heap_locked();
83 if (!SafepointSynchronize::is_at_safepoint()) { 114
84 assert( Heap_lock->owned_by_self(), "invariant" ); 115 // Since we couldn't successfully allocate into it, retire the
85 Heap_lock->unlock(); 116 // current alloc region.
86 } 117 retire_cur_alloc_region(cur_alloc_region);
87 return res;
88 }
89 } 118 }
90 // attempt_allocation_slow will also unlock the heap lock when appropriate. 119
91 return attempt_allocation_slow(word_size, permit_collection_pause); 120 // Try to get a new region and allocate out of it
121 HeapWord* result = replace_cur_alloc_region_and_allocate(word_size,
122 false, /* at safepoint */
123 true /* do_dirtying */);
124 if (result != NULL) {
125 assert_heap_not_locked();
126 return result;
127 }
128
129 assert_heap_locked();
130 return NULL;
131 }
132
133 inline void
134 G1CollectedHeap::retire_cur_alloc_region_common(HeapRegion* cur_alloc_region) {
135 assert_heap_locked_or_at_safepoint();
136 assert(cur_alloc_region != NULL && cur_alloc_region == _cur_alloc_region,
137 "pre-condition of the call");
138 assert(cur_alloc_region->is_young(),
139 "we only support young current alloc regions");
140
141 // The region is guaranteed to be young
142 g1_policy()->add_region_to_incremental_cset_lhs(cur_alloc_region);
143 _summary_bytes_used += cur_alloc_region->used();
144 _cur_alloc_region = NULL;
145 }
146
147 // It dirties the cards that cover the block so that so that the post
148 // write barrier never queues anything when updating objects on this
149 // block. It is assumed (and in fact we assert) that the block
150 // belongs to a young region.
151 inline void
152 G1CollectedHeap::dirty_young_block(HeapWord* start, size_t word_size) {
153 assert_heap_not_locked();
154
155 // Assign the containing region to containing_hr so that we don't
156 // have to keep calling heap_region_containing_raw() in the
157 // asserts below.
158 DEBUG_ONLY(HeapRegion* containing_hr = heap_region_containing_raw(start);)
159 assert(containing_hr != NULL && start != NULL && word_size > 0,
160 "pre-condition");
161 assert(containing_hr->is_in(start), "it should contain start");
162 assert(containing_hr->is_young(), "it should be young");
163 assert(!containing_hr->isHumongous(), "it should not be humongous");
164
165 HeapWord* end = start + word_size;
166 assert(containing_hr->is_in(end - 1), "it should also contain end - 1");
167
168 MemRegion mr(start, end);
169 ((CardTableModRefBS*)_g1h->barrier_set())->dirty(mr);
92 } 170 }
93 171
94 inline RefToScanQueue* G1CollectedHeap::task_queue(int i) const { 172 inline RefToScanQueue* G1CollectedHeap::task_queue(int i) const {
95 return _task_queues->queue(i); 173 return _task_queues->queue(i);
96 } 174 }