jdk8-mips64-public/hotspot: src/share/vm/memory/heap.cpp@6bdd6923ba16 (annotated)

src/share/vm/memory/heap.cpp@6bdd6923ba16 (annotated)

src/share/vm/memory/heap.cpp

Wed, 25 Mar 2009 14:19:20 -0400

author: coleenp
date: Wed, 25 Mar 2009 14:19:20 -0400
changeset 1091: 6bdd6923ba16
parent 631: d1605aabd0a1
child 1279: bd02caa94611
permissions: -rw-r--r--

6541756: Reduce executable C-heap
Summary: Add executable parameters to reserve_memory and commit_memory to reduce executable memory to only the Code Heap.
Reviewed-by: xlu, kvn, acorn

 /*
  * Copyright 1997-2008 Sun Microsystems, Inc.  All Rights Reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
  * under the terms of the GNU General Public License version 2 only, as
  * published by the Free Software Foundation.
  *
  * This code is distributed in the hope that it will be useful, but WITHOUT
  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  * version 2 for more details (a copy is included in the LICENSE file that
  * accompanied this code).
  *
  * You should have received a copy of the GNU General Public License version
  * 2 along with this work; if not, write to the Free Software Foundation,
  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  *
  * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
  * CA 95054 USA or visit www.sun.com if you need additional information or
  * have any questions.
  *
  */
 # include "incls/_precompiled.incl"
 # include "incls/_heap.cpp.incl"
 size_t CodeHeap::header_size() {
   return sizeof(HeapBlock);
 }
 // Implementation of Heap
 CodeHeap::CodeHeap() {
   _number_of_committed_segments = 0;
   _number_of_reserved_segments  = 0;
   _segment_size                 = 0;
   _log2_segment_size            = 0;
   _next_segment                 = 0;
   _freelist                     = NULL;
   _free_segments                = 0;
 }
 void CodeHeap::mark_segmap_as_free(size_t beg, size_t end) {
   assert(0   <= beg && beg <  _number_of_committed_segments, "interval begin out of bounds");
   assert(beg <  end && end <= _number_of_committed_segments, "interval end   out of bounds");
   // setup _segmap pointers for faster indexing
   address p = (address)_segmap.low() + beg;
   address q = (address)_segmap.low() + end;
   // initialize interval
   while (p < q) *p++ = 0xFF;
 }
 void CodeHeap::mark_segmap_as_used(size_t beg, size_t end) {
   assert(0   <= beg && beg <  _number_of_committed_segments, "interval begin out of bounds");
   assert(beg <  end && end <= _number_of_committed_segments, "interval end   out of bounds");
   // setup _segmap pointers for faster indexing
   address p = (address)_segmap.low() + beg;
   address q = (address)_segmap.low() + end;
   // initialize interval
   int i = 0;
   while (p < q) {
     *p++ = i++;
     if (i == 0xFF) i = 1;
   }
 }
 static size_t align_to_page_size(size_t size) {
   const size_t alignment = (size_t)os::vm_page_size();
   assert(is_power_of_2(alignment), "no kidding ???");
   return (size + alignment - 1) & ~(alignment - 1);
 }
 static size_t align_to_allocation_size(size_t size) {
   const size_t alignment = (size_t)os::vm_allocation_granularity();
   assert(is_power_of_2(alignment), "no kidding ???");
   return (size + alignment - 1) & ~(alignment - 1);
 }
 void CodeHeap::on_code_mapping(char* base, size_t size) {
 #ifdef LINUX
   extern void linux_wrap_code(char* base, size_t size);
   linux_wrap_code(base, size);
 #endif
 }
 bool CodeHeap::reserve(size_t reserved_size, size_t committed_size,
                        size_t segment_size) {
   assert(reserved_size >= committed_size, "reserved < committed");
   assert(segment_size >= sizeof(FreeBlock), "segment size is too small");
   assert(is_power_of_2(segment_size), "segment_size must be a power of 2");
   _segment_size      = segment_size;
   _log2_segment_size = exact_log2(segment_size);
   // Reserve and initialize space for _memory.
   const size_t page_size = os::can_execute_large_page_memory() ?
           os::page_size_for_region(committed_size, reserved_size, 8) :
           os::vm_page_size();
   const size_t granularity = os::vm_allocation_granularity();
   const size_t r_align = MAX2(page_size, granularity);
   const size_t r_size = align_size_up(reserved_size, r_align);
   const size_t c_size = align_size_up(committed_size, page_size);
   const size_t rs_align = page_size == (size_t) os::vm_page_size() ? 0 :
     MAX2(page_size, granularity);
   ReservedCodeSpace rs(r_size, rs_align, rs_align > 0);
   os::trace_page_sizes("code heap", committed_size, reserved_size, page_size,
                        rs.base(), rs.size());
   if (!_memory.initialize(rs, c_size)) {
     return false;
   }
   on_code_mapping(_memory.low(), _memory.committed_size());
   _number_of_committed_segments = number_of_segments(_memory.committed_size());
   _number_of_reserved_segments  = number_of_segments(_memory.reserved_size());
   assert(_number_of_reserved_segments >= _number_of_committed_segments, "just checking");
   // reserve space for _segmap
   if (!_segmap.initialize(align_to_page_size(_number_of_reserved_segments), align_to_page_size(_number_of_committed_segments))) {
     return false;
   }
   assert(_segmap.committed_size() >= (size_t) _number_of_committed_segments, "could not commit  enough space for segment map");
   assert(_segmap.reserved_size()  >= (size_t) _number_of_reserved_segments , "could not reserve enough space for segment map");
   assert(_segmap.reserved_size()  >= _segmap.committed_size()     , "just checking");
   // initialize remaining instance variables
   clear();
   return true;
 }
 void CodeHeap::release() {
   Unimplemented();
 }
 bool CodeHeap::expand_by(size_t size) {
   // expand _memory space
   size_t dm = align_to_page_size(_memory.committed_size() + size) - _memory.committed_size();
   if (dm > 0) {
     char* base = _memory.low() + _memory.committed_size();
     if (!_memory.expand_by(dm)) return false;
     on_code_mapping(base, dm);
     size_t i = _number_of_committed_segments;
     _number_of_committed_segments = number_of_segments(_memory.committed_size());
     assert(_number_of_reserved_segments == number_of_segments(_memory.reserved_size()), "number of reserved segments should not change");
     assert(_number_of_reserved_segments >= _number_of_committed_segments, "just checking");
     // expand _segmap space
     size_t ds = align_to_page_size(_number_of_committed_segments) - _segmap.committed_size();
     if (ds > 0) {
       if (!_segmap.expand_by(ds)) return false;
     }
     assert(_segmap.committed_size() >= (size_t) _number_of_committed_segments, "just checking");
     // initialize additional segmap entries
     mark_segmap_as_free(i, _number_of_committed_segments);
   }
   return true;
 }
 void CodeHeap::shrink_by(size_t size) {
   Unimplemented();
 }
 void CodeHeap::clear() {
   _next_segment = 0;
   mark_segmap_as_free(0, _number_of_committed_segments);
 }
 void* CodeHeap::allocate(size_t size) {
   size_t length = number_of_segments(size + sizeof(HeapBlock));
   assert(length *_segment_size >= sizeof(FreeBlock), "not enough room for FreeList");
   // First check if we can satify request from freelist
   debug_only(verify());
   HeapBlock* block = search_freelist(length);
   debug_only(if (VerifyCodeCacheOften) verify());
   if (block != NULL) {
     assert(block->length() >= length && block->length() < length + CodeCacheMinBlockLength, "sanity check");
     assert(!block->free(), "must be marked free");
 #ifdef ASSERT
     memset((void *)block->allocated_space(), badCodeHeapNewVal, size);
 #endif
     return block->allocated_space();
   }
   if (length < CodeCacheMinBlockLength) {
     length = CodeCacheMinBlockLength;
   }
   if (_next_segment + length <= _number_of_committed_segments) {
     mark_segmap_as_used(_next_segment, _next_segment + length);
     HeapBlock* b =  block_at(_next_segment);
     b->initialize(length);
     _next_segment += length;
 #ifdef ASSERT
     memset((void *)b->allocated_space(), badCodeHeapNewVal, size);
 #endif
     return b->allocated_space();
   } else {
     return NULL;
   }
 }
 void CodeHeap::deallocate(void* p) {
   assert(p == find_start(p), "illegal deallocation");
   // Find start of HeapBlock
   HeapBlock* b = (((HeapBlock *)p) - 1);
   assert(b->allocated_space() == p, "sanity check");
 #ifdef ASSERT
   memset((void *)b->allocated_space(),
          badCodeHeapFreeVal,
          size(b->length()) - sizeof(HeapBlock));
 #endif
   add_to_freelist(b);
   debug_only(if (VerifyCodeCacheOften) verify());
 }
 void* CodeHeap::find_start(void* p) const {
   if (!contains(p)) {
     return NULL;
   }
   size_t i = segment_for(p);
   address b = (address)_segmap.low();
   if (b[i] == 0xFF) {
     return NULL;
   }
   while (b[i] > 0) i -= (int)b[i];
   HeapBlock* h = block_at(i);
   if (h->free()) {
     return NULL;
   }
   return h->allocated_space();
 }
 size_t CodeHeap::alignment_unit() const {
   // this will be a power of two
   return _segment_size;
 }
 size_t CodeHeap::alignment_offset() const {
   // The lowest address in any allocated block will be
   // equal to alignment_offset (mod alignment_unit).
   return sizeof(HeapBlock) & (_segment_size - 1);
 }
 // Finds the next free heapblock. If the current one is free, that it returned
 void* CodeHeap::next_free(HeapBlock *b) const {
   // Since free blocks are merged, there is max. on free block
   // between two used ones
   if (b != NULL && b->free()) b = next_block(b);
   assert(b == NULL || !b->free(), "must be in use or at end of heap");
   return (b == NULL) ? NULL : b->allocated_space();
 }
 // Returns the first used HeapBlock
 HeapBlock* CodeHeap::first_block() const {
   if (_next_segment > 0)
     return block_at(0);
   return NULL;
 }
 HeapBlock *CodeHeap::block_start(void *q) const {
   HeapBlock* b = (HeapBlock*)find_start(q);
   if (b == NULL) return NULL;
   return b - 1;
 }
 // Returns the next Heap block an offset into one
 HeapBlock* CodeHeap::next_block(HeapBlock *b) const {
   if (b == NULL) return NULL;
   size_t i = segment_for(b) + b->length();
   if (i < _next_segment)
     return block_at(i);
   return NULL;
 }
 // Returns current capacity
 size_t CodeHeap::capacity() const {
   return _memory.committed_size();
 }
 size_t CodeHeap::max_capacity() const {
   return _memory.reserved_size();
 }
 size_t CodeHeap::allocated_capacity() const {
   // Start with the committed size in _memory;
   size_t l = _memory.committed_size();
   // Subtract the committed, but unused, segments
   l -= size(_number_of_committed_segments - _next_segment);
   // Subtract the size of the freelist
   l -= size(_free_segments);
   return l;
 }
 // Free list management
 FreeBlock *CodeHeap::following_block(FreeBlock *b) {
   return (FreeBlock*)(((address)b) + _segment_size * b->length());
 }
 // Inserts block b after a
 void CodeHeap::insert_after(FreeBlock* a, FreeBlock* b) {
   assert(a != NULL && b != NULL, "must be real pointers");
   // Link b into the list after a
   b->set_link(a->link());
   a->set_link(b);
   // See if we can merge blocks
   merge_right(b); // Try to make b bigger
   merge_right(a); // Try to make a include b
 }
 // Try to merge this block with the following block
 void CodeHeap::merge_right(FreeBlock *a) {
   assert(a->free(), "must be a free block");
   if (following_block(a) == a->link()) {
     assert(a->link() != NULL && a->link()->free(), "must be free too");
     // Update block a to include the following block
     a->set_length(a->length() + a->link()->length());
     a->set_link(a->link()->link());
     // Update find_start map
     size_t beg = segment_for(a);
     mark_segmap_as_used(beg, beg + a->length());
   }
 }
 void CodeHeap::add_to_freelist(HeapBlock *a) {
   FreeBlock* b = (FreeBlock*)a;
   assert(b != _freelist, "cannot be removed twice");
   // Mark as free and update free space count
   _free_segments += b->length();
   b->set_free();
   // First element in list?
   if (_freelist == NULL) {
     _freelist = b;
     b->set_link(NULL);
     return;
   }
   // Scan for right place to put into list. List
   // is sorted by increasing addresseses
   FreeBlock* prev = NULL;
   FreeBlock* cur  = _freelist;
   while(cur != NULL && cur < b) {
     assert(prev == NULL || prev < cur, "must be ordered");
     prev = cur;
     cur  = cur->link();
   }
   assert( (prev == NULL && b < _freelist) ||
           (prev < b && (cur == NULL || b < cur)), "list must be ordered");
   if (prev == NULL) {
     // Insert first in list
     b->set_link(_freelist);
     _freelist = b;
     merge_right(_freelist);
   } else {
     insert_after(prev, b);
   }
 }
 // Search freelist for an entry on the list with the best fit
 // Return NULL if no one was found
 FreeBlock* CodeHeap::search_freelist(size_t length) {
   FreeBlock *best_block = NULL;
   FreeBlock *best_prev  = NULL;
   size_t best_length = 0;
   // Search for smallest block which is bigger than length
   FreeBlock *prev = NULL;
   FreeBlock *cur = _freelist;
   while(cur != NULL) {
     size_t l = cur->length();
     if (l >= length && (best_block == NULL || best_length > l)) {
       // Remember best block, its previous element, and its length
       best_block = cur;
       best_prev  = prev;
       best_length = best_block->length();
     }
     // Next element in list
     prev = cur;
     cur  = cur->link();
   }
   if (best_block == NULL) {
     // None found
     return NULL;
   }
   assert((best_prev == NULL && _freelist == best_block ) ||
          (best_prev != NULL && best_prev->link() == best_block), "sanity check");
   // Exact (or at least good enough) fit. Remove from list.
   // Don't leave anything on the freelist smaller than CodeCacheMinBlockLength.
   if (best_length < length + CodeCacheMinBlockLength) {
     length = best_length;
     if (best_prev == NULL) {
       assert(_freelist == best_block, "sanity check");
       _freelist = _freelist->link();
     } else {
       // Unmap element
       best_prev->set_link(best_block->link());
     }
   } else {
     // Truncate block and return a pointer to the following block
     best_block->set_length(best_length - length);
     best_block = following_block(best_block);
     // Set used bit and length on new block
     size_t beg = segment_for(best_block);
     mark_segmap_as_used(beg, beg + length);
     best_block->set_length(length);
   }
   best_block->set_used();
   _free_segments -= length;
   return best_block;
 }
 //----------------------------------------------------------------------------
 // Non-product code
 #ifndef PRODUCT
 void CodeHeap::print() {
   tty->print_cr("The Heap");
 }
 #endif
 void CodeHeap::verify() {
   // Count the number of blocks on the freelist, and the amount of space
   // represented.
   int count = 0;
   size_t len = 0;
   for(FreeBlock* b = _freelist; b != NULL; b = b->link()) {
     len += b->length();
     count++;
   }
   // Verify that freelist contains the right amount of free space
   guarantee(len == _free_segments, "wrong freelist");
   // 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");
 }

Mercurial > jdk8-mips64-public > hotspot / annotate

src/share/vm/memory/heap.cpp@6bdd6923ba16 (annotated)

src/share/vm/memory/heap.cpp