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8029799: vm/mlvm/anonloader/stress/oome prints warning: CodeHeap: # of free blocks > 10000
Double CodeCacheSegmentSize from 64 byte to 128 bytes if tiered compilation is enabled Reviewed-by: kvn, twisti
This commit is contained in:
Albert Noll
parent
87b278c44c
commit
e8bc971d19
6 changed files with 201 additions and 168 deletions
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@ -43,6 +43,7 @@ CodeHeap::CodeHeap() {
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_next_segment = 0;
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_freelist = NULL;
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_freelist_segments = 0;
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_freelist_length = 0;
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}
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@ -53,7 +54,7 @@ void CodeHeap::mark_segmap_as_free(size_t beg, size_t end) {
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address p = (address)_segmap.low() + beg;
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address q = (address)_segmap.low() + end;
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// initialize interval
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while (p < q) *p++ = 0xFF;
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while (p < q) *p++ = free_sentinel;
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}
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@ -67,7 +68,7 @@ void CodeHeap::mark_segmap_as_used(size_t beg, size_t end) {
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int i = 0;
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while (p < q) {
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*p++ = i++;
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if (i == 0xFF) i = 1;
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if (i == free_sentinel) i = 1;
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}
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}
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@ -139,11 +140,6 @@ bool CodeHeap::reserve(size_t reserved_size, size_t committed_size,
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}
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void CodeHeap::release() {
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Unimplemented();
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}
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bool CodeHeap::expand_by(size_t size) {
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// expand _memory space
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size_t dm = align_to_page_size(_memory.committed_size() + size) - _memory.committed_size();
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@ -157,8 +153,8 @@ bool CodeHeap::expand_by(size_t size) {
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assert(_number_of_reserved_segments >= _number_of_committed_segments, "just checking");
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// expand _segmap space
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size_t ds = align_to_page_size(_number_of_committed_segments) - _segmap.committed_size();
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if (ds > 0) {
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if (!_segmap.expand_by(ds)) return false;
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if ((ds > 0) && !_segmap.expand_by(ds)) {
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return false;
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}
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assert(_segmap.committed_size() >= (size_t) _number_of_committed_segments, "just checking");
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// initialize additional segmap entries
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@ -167,12 +163,6 @@ bool CodeHeap::expand_by(size_t size) {
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return true;
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}
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void CodeHeap::shrink_by(size_t size) {
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Unimplemented();
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}
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void CodeHeap::clear() {
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_next_segment = 0;
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mark_segmap_as_free(0, _number_of_committed_segments);
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@ -180,26 +170,23 @@ void CodeHeap::clear() {
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void* CodeHeap::allocate(size_t instance_size, bool is_critical) {
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size_t number_of_segments = size_to_segments(instance_size + sizeof(HeapBlock));
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size_t number_of_segments = size_to_segments(instance_size + header_size());
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assert(segments_to_size(number_of_segments) >= sizeof(FreeBlock), "not enough room for FreeList");
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// First check if we can satisfy request from freelist
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debug_only(verify());
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NOT_PRODUCT(verify());
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HeapBlock* block = search_freelist(number_of_segments, is_critical);
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debug_only(if (VerifyCodeCacheOften) verify());
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NOT_PRODUCT(verify());
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if (block != NULL) {
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assert(block->length() >= number_of_segments && block->length() < number_of_segments + CodeCacheMinBlockLength, "sanity check");
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assert(!block->free(), "must be marked free");
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#ifdef ASSERT
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memset((void *)block->allocated_space(), badCodeHeapNewVal, instance_size);
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#endif
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DEBUG_ONLY(memset((void*)block->allocated_space(), badCodeHeapNewVal, instance_size));
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return block->allocated_space();
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}
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// Ensure minimum size for allocation to the heap.
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if (number_of_segments < CodeCacheMinBlockLength) {
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number_of_segments = CodeCacheMinBlockLength;
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}
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number_of_segments = MAX2((int)CodeCacheMinBlockLength, (int)number_of_segments);
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if (!is_critical) {
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// Make sure the allocation fits in the unallocated heap without using
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@ -215,9 +202,7 @@ void* CodeHeap::allocate(size_t instance_size, bool is_critical) {
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HeapBlock* b = block_at(_next_segment);
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b->initialize(number_of_segments);
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_next_segment += number_of_segments;
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#ifdef ASSERT
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memset((void *)b->allocated_space(), badCodeHeapNewVal, instance_size);
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#endif
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DEBUG_ONLY(memset((void *)b->allocated_space(), badCodeHeapNewVal, instance_size));
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return b->allocated_space();
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} else {
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return NULL;
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@ -230,28 +215,56 @@ void CodeHeap::deallocate(void* p) {
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// Find start of HeapBlock
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HeapBlock* b = (((HeapBlock *)p) - 1);
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assert(b->allocated_space() == p, "sanity check");
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#ifdef ASSERT
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memset((void *)b->allocated_space(),
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badCodeHeapFreeVal,
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segments_to_size(b->length()) - sizeof(HeapBlock));
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#endif
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DEBUG_ONLY(memset((void *)b->allocated_space(), badCodeHeapFreeVal,
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segments_to_size(b->length()) - sizeof(HeapBlock)));
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add_to_freelist(b);
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debug_only(if (VerifyCodeCacheOften) verify());
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NOT_PRODUCT(verify());
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}
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/**
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* Uses segment map to find the the start (header) of a nmethod. This works as follows:
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* The memory of the code cache is divided into 'segments'. The size of a segment is
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* determined by -XX:CodeCacheSegmentSize=XX. Allocation in the code cache can only
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* happen at segment boundaries. A pointer in the code cache can be mapped to a segment
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* by calling segment_for(addr). Each time memory is requested from the code cache,
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* the segmap is updated accordingly. See the following example, which illustrates the
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* state of code cache and the segment map: (seg -> segment, nm ->nmethod)
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*
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* code cache segmap
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* ----------- ---------
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* seg 1 | nm 1 | -> | 0 |
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* seg 2 | nm 1 | -> | 1 |
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* ... | nm 1 | -> | .. |
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* seg m | nm 2 | -> | 0 |
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* seg m+1 | nm 2 | -> | 1 |
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* ... | nm 2 | -> | 2 |
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* ... | nm 2 | -> | .. |
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* ... | nm 2 | -> | 0xFE |
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* seg m+n | nm 2 | -> | 1 |
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* ... | nm 2 | -> | |
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*
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* A value of '0' in the segmap indicates that this segment contains the beginning of
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* an nmethod. Let's walk through a simple example: If we want to find the start of
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* an nmethod that falls into seg 2, we read the value of the segmap[2]. The value
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* is an offset that points to the segment that contains the start of the nmethod.
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* Another example: If we want to get the start of nm 2, and we happen to get a pointer
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* that points to seg m+n, we first read seg[n+m], which returns '1'. So we have to
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* do one more read of the segmap[m+n-1] to finally get the segment header.
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*/
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void* CodeHeap::find_start(void* p) const {
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if (!contains(p)) {
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return NULL;
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}
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size_t i = segment_for(p);
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address b = (address)_segmap.low();
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if (b[i] == 0xFF) {
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size_t seg_idx = segment_for(p);
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address seg_map = (address)_segmap.low();
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if (is_segment_unused(seg_map[seg_idx])) {
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return NULL;
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}
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while (b[i] > 0) i -= (int)b[i];
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HeapBlock* h = block_at(i);
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while (seg_map[seg_idx] > 0) {
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seg_idx -= (int)seg_map[seg_idx];
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}
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HeapBlock* h = block_at(seg_idx);
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if (h->free()) {
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return NULL;
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}
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@ -272,7 +285,7 @@ size_t CodeHeap::alignment_offset() const {
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}
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// Finds the next free heapblock. If the current one is free, that it returned
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void* CodeHeap::next_free(HeapBlock *b) const {
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void* CodeHeap::next_free(HeapBlock* b) const {
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// Since free blocks are merged, there is max. on free block
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// between two used ones
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if (b != NULL && b->free()) b = next_block(b);
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@ -287,7 +300,7 @@ HeapBlock* CodeHeap::first_block() const {
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return NULL;
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}
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HeapBlock *CodeHeap::block_start(void *q) const {
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HeapBlock* CodeHeap::block_start(void* q) const {
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HeapBlock* b = (HeapBlock*)find_start(q);
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if (b == NULL) return NULL;
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return b - 1;
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@ -312,6 +325,10 @@ size_t CodeHeap::max_capacity() const {
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return _memory.reserved_size();
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}
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int CodeHeap::allocated_segments() const {
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return (int)_next_segment;
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}
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size_t CodeHeap::allocated_capacity() const {
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// size of used heap - size on freelist
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return segments_to_size(_next_segment - _freelist_segments);
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@ -325,7 +342,7 @@ size_t CodeHeap::heap_unallocated_capacity() const {
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// Free list management
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FreeBlock *CodeHeap::following_block(FreeBlock *b) {
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FreeBlock* CodeHeap::following_block(FreeBlock *b) {
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return (FreeBlock*)(((address)b) + _segment_size * b->length());
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}
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@ -343,7 +360,7 @@ void CodeHeap::insert_after(FreeBlock* a, FreeBlock* b) {
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}
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// Try to merge this block with the following block
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void CodeHeap::merge_right(FreeBlock *a) {
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bool CodeHeap::merge_right(FreeBlock* a) {
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assert(a->free(), "must be a free block");
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if (following_block(a) == a->link()) {
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assert(a->link() != NULL && a->link()->free(), "must be free too");
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@ -353,13 +370,20 @@ void CodeHeap::merge_right(FreeBlock *a) {
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// Update find_start map
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size_t beg = segment_for(a);
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mark_segmap_as_used(beg, beg + a->length());
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_freelist_length--;
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return true;
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}
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return false;
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}
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void CodeHeap::add_to_freelist(HeapBlock *a) {
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void CodeHeap::add_to_freelist(HeapBlock* a) {
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FreeBlock* b = (FreeBlock*)a;
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_freelist_length++;
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assert(b != _freelist, "cannot be removed twice");
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// Mark as free and update free space count
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_freelist_segments += b->length();
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b->set_free();
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@ -371,95 +395,96 @@ void CodeHeap::add_to_freelist(HeapBlock *a) {
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return;
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}
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// Scan for right place to put into list. List
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// is sorted by increasing addresses
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FreeBlock* prev = NULL;
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FreeBlock* cur = _freelist;
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while(cur != NULL && cur < b) {
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assert(prev == NULL || prev < cur, "must be ordered");
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prev = cur;
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cur = cur->link();
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}
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assert( (prev == NULL && b < _freelist) ||
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(prev < b && (cur == NULL || b < cur)), "list must be ordered");
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if (prev == NULL) {
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// Since the freelist is ordered (smaller addresses -> larger addresses) and the
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// element we want to insert into the freelist has a smaller address than the first
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// element, we can simply add 'b' as the first element and we are done.
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if (b < _freelist) {
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// Insert first in list
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b->set_link(_freelist);
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_freelist = b;
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merge_right(_freelist);
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} else {
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insert_after(prev, b);
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return;
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}
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// Scan for right place to put into list. List
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// is sorted by increasing addresses
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FreeBlock* prev = _freelist;
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FreeBlock* cur = _freelist->link();
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while(cur != NULL && cur < b) {
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assert(prev < cur, "Freelist must be ordered");
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prev = cur;
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cur = cur->link();
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}
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assert((prev < b) && (cur == NULL || b < cur), "free-list must be ordered");
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insert_after(prev, b);
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}
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// Search freelist for an entry on the list with the best fit
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// Return NULL if no one was found
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/**
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* Search freelist for an entry on the list with the best fit.
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* @return NULL, if no one was found
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*/
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FreeBlock* CodeHeap::search_freelist(size_t length, bool is_critical) {
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FreeBlock *best_block = NULL;
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FreeBlock *best_prev = NULL;
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size_t best_length = 0;
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FreeBlock* found_block = NULL;
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FreeBlock* found_prev = NULL;
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size_t found_length = 0;
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// Search for smallest block which is bigger than length
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FreeBlock *prev = NULL;
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FreeBlock *cur = _freelist;
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FreeBlock* prev = NULL;
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FreeBlock* cur = _freelist;
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const size_t critical_boundary = (size_t)high_boundary() - CodeCacheMinimumFreeSpace;
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// Search for first block that fits
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while(cur != NULL) {
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size_t l = cur->length();
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if (l >= length && (best_block == NULL || best_length > l)) {
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if (cur->length() >= length) {
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// Non critical allocations are not allowed to use the last part of the code heap.
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if (!is_critical) {
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// Make sure the end of the allocation doesn't cross into the last part of the code heap
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if (((size_t)cur + length) > ((size_t)high_boundary() - CodeCacheMinimumFreeSpace)) {
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// the freelist is sorted by address - if one fails, all consecutive will also fail.
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break;
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}
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// Make sure the end of the allocation doesn't cross into the last part of the code heap.
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if (!is_critical && (((size_t)cur + length) > critical_boundary)) {
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// The freelist is sorted by address - if one fails, all consecutive will also fail.
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break;
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}
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// Remember block, its previous element, and its length
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found_block = cur;
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found_prev = prev;
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found_length = found_block->length();
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// Remember best block, its previous element, and its length
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best_block = cur;
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best_prev = prev;
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best_length = best_block->length();
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break;
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}
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// Next element in list
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prev = cur;
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cur = cur->link();
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}
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if (best_block == NULL) {
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if (found_block == NULL) {
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// None found
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return NULL;
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}
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assert((best_prev == NULL && _freelist == best_block ) ||
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(best_prev != NULL && best_prev->link() == best_block), "sanity check");
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// Exact (or at least good enough) fit. Remove from list.
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// Don't leave anything on the freelist smaller than CodeCacheMinBlockLength.
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if (best_length < length + CodeCacheMinBlockLength) {
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length = best_length;
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if (best_prev == NULL) {
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assert(_freelist == best_block, "sanity check");
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if (found_length - length < CodeCacheMinBlockLength) {
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_freelist_length--;
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length = found_length;
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if (found_prev == NULL) {
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assert(_freelist == found_block, "sanity check");
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_freelist = _freelist->link();
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} else {
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assert((found_prev->link() == found_block), "sanity check");
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// Unmap element
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best_prev->set_link(best_block->link());
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found_prev->set_link(found_block->link());
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}
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} else {
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// Truncate block and return a pointer to the following block
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best_block->set_length(best_length - length);
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best_block = following_block(best_block);
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// Set used bit and length on new block
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size_t beg = segment_for(best_block);
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found_block->set_length(found_length - length);
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found_block = following_block(found_block);
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size_t beg = segment_for(found_block);
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mark_segmap_as_used(beg, beg + length);
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best_block->set_length(length);
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found_block->set_length(length);
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}
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best_block->set_used();
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found_block->set_used();
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_freelist_segments -= length;
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return best_block;
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return found_block;
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}
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//----------------------------------------------------------------------------
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@ -471,33 +496,34 @@ void CodeHeap::print() {
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tty->print_cr("The Heap");
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}
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#endif
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void CodeHeap::verify() {
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// Count the number of blocks on the freelist, and the amount of space
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// represented.
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int count = 0;
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size_t len = 0;
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for(FreeBlock* b = _freelist; b != NULL; b = b->link()) {
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len += b->length();
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count++;
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}
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if (VerifyCodeCache) {
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size_t len = 0;
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int count = 0;
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for(FreeBlock* b = _freelist; b != NULL; b = b->link()) {
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len += b->length();
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count++;
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// Check if we have merged all free blocks
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assert(merge_right(b) == false, "Missed merging opportunity");
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}
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// Verify that freelist contains the right amount of free space
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assert(len == _freelist_segments, "wrong freelist");
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// Verify that freelist contains the right amount of free space
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// guarantee(len == _freelist_segments, "wrong freelist");
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for(HeapBlock* h = first_block(); h != NULL; h = next_block(h)) {
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if (h->free()) count--;
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}
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// Verify that the freelist contains the same number of blocks
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// than free blocks found on the full list.
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assert(count == 0, "missing free blocks");
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// Verify that the number of free blocks is not out of hand.
|
||||
static int free_block_threshold = 10000;
|
||||
if (count > free_block_threshold) {
|
||||
warning("CodeHeap: # of free blocks > %d", free_block_threshold);
|
||||
// Double the warning limit
|
||||
free_block_threshold *= 2;
|
||||
// Verify that the number of free blocks is not out of hand.
|
||||
static int free_block_threshold = 10000;
|
||||
if (count > free_block_threshold) {
|
||||
warning("CodeHeap: # of free blocks > %d", free_block_threshold);
|
||||
// Double the warning limit
|
||||
free_block_threshold *= 2;
|
||||
}
|
||||
}
|
||||
|
||||
// Verify that the freelist contains the same number of free blocks that is
|
||||
// found on the full list.
|
||||
for(HeapBlock *h = first_block(); h != NULL; h = next_block(h)) {
|
||||
if (h->free()) count--;
|
||||
}
|
||||
// guarantee(count == 0, "missing free blocks");
|
||||
}
|
||||
|
||||
#endif
|
||||
|
|
|
|||
Loading…
Add table
Add a link
Reference in a new issue