| OLD | NEW |
| 1 // Copyright 2011 the V8 project authors. All rights reserved. | 1 // Copyright 2011 the V8 project authors. All rights reserved. |
| 2 // Redistribution and use in source and binary forms, with or without | 2 // Redistribution and use in source and binary forms, with or without |
| 3 // modification, are permitted provided that the following conditions are | 3 // modification, are permitted provided that the following conditions are |
| 4 // met: | 4 // met: |
| 5 // | 5 // |
| 6 // * Redistributions of source code must retain the above copyright | 6 // * Redistributions of source code must retain the above copyright |
| 7 // notice, this list of conditions and the following disclaimer. | 7 // notice, this list of conditions and the following disclaimer. |
| 8 // * Redistributions in binary form must reproduce the above | 8 // * Redistributions in binary form must reproduce the above |
| 9 // copyright notice, this list of conditions and the following | 9 // copyright notice, this list of conditions and the following |
| 10 // disclaimer in the documentation and/or other materials provided | 10 // disclaimer in the documentation and/or other materials provided |
| (...skipping 16 matching lines...) Expand all Loading... |
| 27 | 27 |
| 28 #include "v8.h" | 28 #include "v8.h" |
| 29 | 29 |
| 30 #include "zone-inl.h" | 30 #include "zone-inl.h" |
| 31 #include "splay-tree-inl.h" | 31 #include "splay-tree-inl.h" |
| 32 | 32 |
| 33 namespace v8 { | 33 namespace v8 { |
| 34 namespace internal { | 34 namespace internal { |
| 35 | 35 |
| 36 | 36 |
| 37 Address Zone::position_ = 0; | 37 Zone::Zone() |
| 38 Address Zone::limit_ = 0; | 38 : zone_excess_limit_(256 * MB), |
| 39 int Zone::zone_excess_limit_ = 256 * MB; | 39 segment_bytes_allocated_(0), |
| 40 int Zone::segment_bytes_allocated_ = 0; | 40 position_(0), |
| 41 limit_(0), |
| 42 scope_nesting_(0), |
| 43 segment_head_(NULL) { |
| 44 } |
| 41 unsigned Zone::allocation_size_ = 0; | 45 unsigned Zone::allocation_size_ = 0; |
| 42 | 46 |
| 43 bool AssertNoZoneAllocation::allow_allocation_ = true; | |
| 44 | 47 |
| 45 int ZoneScope::nesting_ = 0; | 48 ZoneScope::~ZoneScope() { |
| 49 ASSERT_EQ(Isolate::Current(), isolate_); |
| 50 if (ShouldDeleteOnExit()) isolate_->zone()->DeleteAll(); |
| 51 isolate_->zone()->scope_nesting_--; |
| 52 } |
| 53 |
| 46 | 54 |
| 47 // Segments represent chunks of memory: They have starting address | 55 // Segments represent chunks of memory: They have starting address |
| 48 // (encoded in the this pointer) and a size in bytes. Segments are | 56 // (encoded in the this pointer) and a size in bytes. Segments are |
| 49 // chained together forming a LIFO structure with the newest segment | 57 // chained together forming a LIFO structure with the newest segment |
| 50 // available as Segment::head(). Segments are allocated using malloc() | 58 // available as segment_head_. Segments are allocated using malloc() |
| 51 // and de-allocated using free(). | 59 // and de-allocated using free(). |
| 52 | 60 |
| 53 class Segment { | 61 class Segment { |
| 54 public: | 62 public: |
| 55 Segment* next() const { return next_; } | 63 Segment* next() const { return next_; } |
| 56 void clear_next() { next_ = NULL; } | 64 void clear_next() { next_ = NULL; } |
| 57 | 65 |
| 58 int size() const { return size_; } | 66 int size() const { return size_; } |
| 59 int capacity() const { return size_ - sizeof(Segment); } | 67 int capacity() const { return size_ - sizeof(Segment); } |
| 60 | 68 |
| 61 Address start() const { return address(sizeof(Segment)); } | 69 Address start() const { return address(sizeof(Segment)); } |
| 62 Address end() const { return address(size_); } | 70 Address end() const { return address(size_); } |
| 63 | 71 |
| 64 static Segment* head() { return head_; } | |
| 65 static void set_head(Segment* head) { head_ = head; } | |
| 66 | |
| 67 // Creates a new segment, sets it size, and pushes it to the front | |
| 68 // of the segment chain. Returns the new segment. | |
| 69 static Segment* New(int size) { | |
| 70 Segment* result = reinterpret_cast<Segment*>(Malloced::New(size)); | |
| 71 Zone::adjust_segment_bytes_allocated(size); | |
| 72 if (result != NULL) { | |
| 73 result->next_ = head_; | |
| 74 result->size_ = size; | |
| 75 head_ = result; | |
| 76 } | |
| 77 return result; | |
| 78 } | |
| 79 | |
| 80 // Deletes the given segment. Does not touch the segment chain. | |
| 81 static void Delete(Segment* segment, int size) { | |
| 82 Zone::adjust_segment_bytes_allocated(-size); | |
| 83 Malloced::Delete(segment); | |
| 84 } | |
| 85 | |
| 86 static int bytes_allocated() { return bytes_allocated_; } | |
| 87 | |
| 88 private: | 72 private: |
| 89 // Computes the address of the nth byte in this segment. | 73 // Computes the address of the nth byte in this segment. |
| 90 Address address(int n) const { | 74 Address address(int n) const { |
| 91 return Address(this) + n; | 75 return Address(this) + n; |
| 92 } | 76 } |
| 93 | 77 |
| 94 static Segment* head_; | |
| 95 static int bytes_allocated_; | |
| 96 Segment* next_; | 78 Segment* next_; |
| 97 int size_; | 79 int size_; |
| 80 |
| 81 friend class Zone; |
| 98 }; | 82 }; |
| 99 | 83 |
| 100 | 84 |
| 101 Segment* Segment::head_ = NULL; | 85 // Creates a new segment, sets it size, and pushes it to the front |
| 102 int Segment::bytes_allocated_ = 0; | 86 // of the segment chain. Returns the new segment. |
| 87 Segment* Zone::NewSegment(int size) { |
| 88 Segment* result = reinterpret_cast<Segment*>(Malloced::New(size)); |
| 89 adjust_segment_bytes_allocated(size); |
| 90 if (result != NULL) { |
| 91 result->next_ = segment_head_; |
| 92 result->size_ = size; |
| 93 segment_head_ = result; |
| 94 } |
| 95 return result; |
| 96 } |
| 97 |
| 98 |
| 99 // Deletes the given segment. Does not touch the segment chain. |
| 100 void Zone::DeleteSegment(Segment* segment, int size) { |
| 101 adjust_segment_bytes_allocated(-size); |
| 102 Malloced::Delete(segment); |
| 103 } |
| 103 | 104 |
| 104 | 105 |
| 105 void Zone::DeleteAll() { | 106 void Zone::DeleteAll() { |
| 106 #ifdef DEBUG | 107 #ifdef DEBUG |
| 107 // Constant byte value used for zapping dead memory in debug mode. | 108 // Constant byte value used for zapping dead memory in debug mode. |
| 108 static const unsigned char kZapDeadByte = 0xcd; | 109 static const unsigned char kZapDeadByte = 0xcd; |
| 109 #endif | 110 #endif |
| 110 | 111 |
| 111 // Find a segment with a suitable size to keep around. | 112 // Find a segment with a suitable size to keep around. |
| 112 Segment* keep = Segment::head(); | 113 Segment* keep = segment_head_; |
| 113 while (keep != NULL && keep->size() > kMaximumKeptSegmentSize) { | 114 while (keep != NULL && keep->size() > kMaximumKeptSegmentSize) { |
| 114 keep = keep->next(); | 115 keep = keep->next(); |
| 115 } | 116 } |
| 116 | 117 |
| 117 // Traverse the chained list of segments, zapping (in debug mode) | 118 // Traverse the chained list of segments, zapping (in debug mode) |
| 118 // and freeing every segment except the one we wish to keep. | 119 // and freeing every segment except the one we wish to keep. |
| 119 Segment* current = Segment::head(); | 120 Segment* current = segment_head_; |
| 120 while (current != NULL) { | 121 while (current != NULL) { |
| 121 Segment* next = current->next(); | 122 Segment* next = current->next(); |
| 122 if (current == keep) { | 123 if (current == keep) { |
| 123 // Unlink the segment we wish to keep from the list. | 124 // Unlink the segment we wish to keep from the list. |
| 124 current->clear_next(); | 125 current->clear_next(); |
| 125 } else { | 126 } else { |
| 126 int size = current->size(); | 127 int size = current->size(); |
| 127 #ifdef DEBUG | 128 #ifdef DEBUG |
| 128 // Zap the entire current segment (including the header). | 129 // Zap the entire current segment (including the header). |
| 129 memset(current, kZapDeadByte, size); | 130 memset(current, kZapDeadByte, size); |
| 130 #endif | 131 #endif |
| 131 Segment::Delete(current, size); | 132 DeleteSegment(current, size); |
| 132 } | 133 } |
| 133 current = next; | 134 current = next; |
| 134 } | 135 } |
| 135 | 136 |
| 136 // If we have found a segment we want to keep, we must recompute the | 137 // If we have found a segment we want to keep, we must recompute the |
| 137 // variables 'position' and 'limit' to prepare for future allocate | 138 // variables 'position' and 'limit' to prepare for future allocate |
| 138 // attempts. Otherwise, we must clear the position and limit to | 139 // attempts. Otherwise, we must clear the position and limit to |
| 139 // force a new segment to be allocated on demand. | 140 // force a new segment to be allocated on demand. |
| 140 if (keep != NULL) { | 141 if (keep != NULL) { |
| 141 Address start = keep->start(); | 142 Address start = keep->start(); |
| 142 position_ = RoundUp(start, kAlignment); | 143 position_ = RoundUp(start, kAlignment); |
| 143 limit_ = keep->end(); | 144 limit_ = keep->end(); |
| 144 #ifdef DEBUG | 145 #ifdef DEBUG |
| 145 // Zap the contents of the kept segment (but not the header). | 146 // Zap the contents of the kept segment (but not the header). |
| 146 memset(start, kZapDeadByte, keep->capacity()); | 147 memset(start, kZapDeadByte, keep->capacity()); |
| 147 #endif | 148 #endif |
| 148 } else { | 149 } else { |
| 149 position_ = limit_ = 0; | 150 position_ = limit_ = 0; |
| 150 } | 151 } |
| 151 | 152 |
| 152 // Update the head segment to be the kept segment (if any). | 153 // Update the head segment to be the kept segment (if any). |
| 153 Segment::set_head(keep); | 154 segment_head_ = keep; |
| 154 } | 155 } |
| 155 | 156 |
| 156 | 157 |
| 157 Address Zone::NewExpand(int size) { | 158 Address Zone::NewExpand(int size) { |
| 158 // Make sure the requested size is already properly aligned and that | 159 // Make sure the requested size is already properly aligned and that |
| 159 // there isn't enough room in the Zone to satisfy the request. | 160 // there isn't enough room in the Zone to satisfy the request. |
| 160 ASSERT(size == RoundDown(size, kAlignment)); | 161 ASSERT(size == RoundDown(size, kAlignment)); |
| 161 ASSERT(position_ + size > limit_); | 162 ASSERT(position_ + size > limit_); |
| 162 | 163 |
| 163 // Compute the new segment size. We use a 'high water mark' | 164 // Compute the new segment size. We use a 'high water mark' |
| 164 // strategy, where we increase the segment size every time we expand | 165 // strategy, where we increase the segment size every time we expand |
| 165 // except that we employ a maximum segment size when we delete. This | 166 // except that we employ a maximum segment size when we delete. This |
| 166 // is to avoid excessive malloc() and free() overhead. | 167 // is to avoid excessive malloc() and free() overhead. |
| 167 Segment* head = Segment::head(); | 168 Segment* head = segment_head_; |
| 168 int old_size = (head == NULL) ? 0 : head->size(); | 169 int old_size = (head == NULL) ? 0 : head->size(); |
| 169 static const int kSegmentOverhead = sizeof(Segment) + kAlignment; | 170 static const int kSegmentOverhead = sizeof(Segment) + kAlignment; |
| 170 int new_size = kSegmentOverhead + size + (old_size << 1); | 171 int new_size = kSegmentOverhead + size + (old_size << 1); |
| 171 if (new_size < kMinimumSegmentSize) { | 172 if (new_size < kMinimumSegmentSize) { |
| 172 new_size = kMinimumSegmentSize; | 173 new_size = kMinimumSegmentSize; |
| 173 } else if (new_size > kMaximumSegmentSize) { | 174 } else if (new_size > kMaximumSegmentSize) { |
| 174 // Limit the size of new segments to avoid growing the segment size | 175 // Limit the size of new segments to avoid growing the segment size |
| 175 // exponentially, thus putting pressure on contiguous virtual address space. | 176 // exponentially, thus putting pressure on contiguous virtual address space. |
| 176 // All the while making sure to allocate a segment large enough to hold the | 177 // All the while making sure to allocate a segment large enough to hold the |
| 177 // requested size. | 178 // requested size. |
| 178 new_size = Max(kSegmentOverhead + size, kMaximumSegmentSize); | 179 new_size = Max(kSegmentOverhead + size, kMaximumSegmentSize); |
| 179 } | 180 } |
| 180 Segment* segment = Segment::New(new_size); | 181 Segment* segment = NewSegment(new_size); |
| 181 if (segment == NULL) { | 182 if (segment == NULL) { |
| 182 V8::FatalProcessOutOfMemory("Zone"); | 183 V8::FatalProcessOutOfMemory("Zone"); |
| 183 return NULL; | 184 return NULL; |
| 184 } | 185 } |
| 185 | 186 |
| 186 // Recompute 'top' and 'limit' based on the new segment. | 187 // Recompute 'top' and 'limit' based on the new segment. |
| 187 Address result = RoundUp(segment->start(), kAlignment); | 188 Address result = RoundUp(segment->start(), kAlignment); |
| 188 position_ = result + size; | 189 position_ = result + size; |
| 189 limit_ = segment->end(); | 190 limit_ = segment->end(); |
| 190 ASSERT(position_ <= limit_); | 191 ASSERT(position_ <= limit_); |
| 191 return result; | 192 return result; |
| 192 } | 193 } |
| 193 | 194 |
| 194 | 195 |
| 195 } } // namespace v8::internal | 196 } } // namespace v8::internal |
| OLD | NEW |