hotspot/src/share/vm/memory/heap.cpp
author coleenp
Wed, 25 Mar 2009 14:19:20 -0400
changeset 2268 bea8be80ec88
parent 670 ddf3e9583f2f
child 3261 c7d5aae8d3f7
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
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/*
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 * Copyright 1997-2008 Sun Microsystems, Inc.  All Rights Reserved.
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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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 *
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 * This code is free software; you can redistribute it and/or modify it
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 * under the terms of the GNU General Public License version 2 only, as
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 * published by the Free Software Foundation.
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 *
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 * This code is distributed in the hope that it will be useful, but WITHOUT
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 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
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 * version 2 for more details (a copy is included in the LICENSE file that
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 * accompanied this code).
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 *
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 * You should have received a copy of the GNU General Public License version
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 * 2 along with this work; if not, write to the Free Software Foundation,
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 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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 *
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 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
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 * CA 95054 USA or visit www.sun.com if you need additional information or
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 * have any questions.
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 *
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 */
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# include "incls/_precompiled.incl"
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# include "incls/_heap.cpp.incl"
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size_t CodeHeap::header_size() {
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  return sizeof(HeapBlock);
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}
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// Implementation of Heap
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CodeHeap::CodeHeap() {
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  _number_of_committed_segments = 0;
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  _number_of_reserved_segments  = 0;
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  _segment_size                 = 0;
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  _log2_segment_size            = 0;
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  _next_segment                 = 0;
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  _freelist                     = NULL;
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  _free_segments                = 0;
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}
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void CodeHeap::mark_segmap_as_free(size_t beg, size_t end) {
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  assert(0   <= beg && beg <  _number_of_committed_segments, "interval begin out of bounds");
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  assert(beg <  end && end <= _number_of_committed_segments, "interval end   out of bounds");
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  // setup _segmap pointers for faster indexing
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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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}
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void CodeHeap::mark_segmap_as_used(size_t beg, size_t end) {
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  assert(0   <= beg && beg <  _number_of_committed_segments, "interval begin out of bounds");
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  assert(beg <  end && end <= _number_of_committed_segments, "interval end   out of bounds");
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  // setup _segmap pointers for faster indexing
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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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  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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  }
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}
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static size_t align_to_page_size(size_t size) {
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  const size_t alignment = (size_t)os::vm_page_size();
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  assert(is_power_of_2(alignment), "no kidding ???");
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  return (size + alignment - 1) & ~(alignment - 1);
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}
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static size_t align_to_allocation_size(size_t size) {
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  const size_t alignment = (size_t)os::vm_allocation_granularity();
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  assert(is_power_of_2(alignment), "no kidding ???");
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  return (size + alignment - 1) & ~(alignment - 1);
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}
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void CodeHeap::on_code_mapping(char* base, size_t size) {
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#ifdef LINUX
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  extern void linux_wrap_code(char* base, size_t size);
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  linux_wrap_code(base, size);
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#endif
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}
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bool CodeHeap::reserve(size_t reserved_size, size_t committed_size,
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                       size_t segment_size) {
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  assert(reserved_size >= committed_size, "reserved < committed");
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  assert(segment_size >= sizeof(FreeBlock), "segment size is too small");
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  assert(is_power_of_2(segment_size), "segment_size must be a power of 2");
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  _segment_size      = segment_size;
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  _log2_segment_size = exact_log2(segment_size);
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  // Reserve and initialize space for _memory.
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  const size_t page_size = os::can_execute_large_page_memory() ?
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          os::page_size_for_region(committed_size, reserved_size, 8) :
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          os::vm_page_size();
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  const size_t granularity = os::vm_allocation_granularity();
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  const size_t r_align = MAX2(page_size, granularity);
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  const size_t r_size = align_size_up(reserved_size, r_align);
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  const size_t c_size = align_size_up(committed_size, page_size);
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  const size_t rs_align = page_size == (size_t) os::vm_page_size() ? 0 :
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    MAX2(page_size, granularity);
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  ReservedCodeSpace rs(r_size, rs_align, rs_align > 0);
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  os::trace_page_sizes("code heap", committed_size, reserved_size, page_size,
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                       rs.base(), rs.size());
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  if (!_memory.initialize(rs, c_size)) {
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    return false;
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  }
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  on_code_mapping(_memory.low(), _memory.committed_size());
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  _number_of_committed_segments = number_of_segments(_memory.committed_size());
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  _number_of_reserved_segments  = number_of_segments(_memory.reserved_size());
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  assert(_number_of_reserved_segments >= _number_of_committed_segments, "just checking");
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  // reserve space for _segmap
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  if (!_segmap.initialize(align_to_page_size(_number_of_reserved_segments), align_to_page_size(_number_of_committed_segments))) {
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    return false;
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  }
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  assert(_segmap.committed_size() >= (size_t) _number_of_committed_segments, "could not commit  enough space for segment map");
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  assert(_segmap.reserved_size()  >= (size_t) _number_of_reserved_segments , "could not reserve enough space for segment map");
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  assert(_segmap.reserved_size()  >= _segmap.committed_size()     , "just checking");
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  // initialize remaining instance variables
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  clear();
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  return true;
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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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  if (dm > 0) {
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    char* base = _memory.low() + _memory.committed_size();
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    if (!_memory.expand_by(dm)) return false;
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    on_code_mapping(base, dm);
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    size_t i = _number_of_committed_segments;
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    _number_of_committed_segments = number_of_segments(_memory.committed_size());
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    assert(_number_of_reserved_segments == number_of_segments(_memory.reserved_size()), "number of reserved segments should not change");
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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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    }
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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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    mark_segmap_as_free(i, _number_of_committed_segments);
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  }
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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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}
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void* CodeHeap::allocate(size_t size) {
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  size_t length = number_of_segments(size + sizeof(HeapBlock));
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  assert(length *_segment_size >= sizeof(FreeBlock), "not enough room for FreeList");
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  // First check if we can satify request from freelist
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  debug_only(verify());
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  HeapBlock* block = search_freelist(length);
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  debug_only(if (VerifyCodeCacheOften) verify());
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  if (block != NULL) {
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    assert(block->length() >= length && block->length() < length + 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, size);
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#endif
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    return block->allocated_space();
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  }
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  if (length < CodeCacheMinBlockLength) {
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    length = CodeCacheMinBlockLength;
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  }
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  if (_next_segment + length <= _number_of_committed_segments) {
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    mark_segmap_as_used(_next_segment, _next_segment + length);
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    HeapBlock* b =  block_at(_next_segment);
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    b->initialize(length);
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    _next_segment += length;
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#ifdef ASSERT
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    memset((void *)b->allocated_space(), badCodeHeapNewVal, size);
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#endif
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    return b->allocated_space();
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  } else {
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    return NULL;
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  }
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}
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void CodeHeap::deallocate(void* p) {
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  assert(p == find_start(p), "illegal deallocation");
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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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         size(b->length()) - sizeof(HeapBlock));
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#endif
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  add_to_freelist(b);
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  debug_only(if (VerifyCodeCacheOften) verify());
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}
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   231
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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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    return NULL;
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  }
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   241
  while (b[i] > 0) i -= (int)b[i];
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   242
  HeapBlock* h = block_at(i);
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  if (h->free()) {
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    return NULL;
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  }
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  return h->allocated_space();
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}
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   249
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size_t CodeHeap::alignment_unit() const {
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  // this will be a power of two
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  return _segment_size;
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}
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size_t CodeHeap::alignment_offset() const {
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  // The lowest address in any allocated block will be
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  // equal to alignment_offset (mod alignment_unit).
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  return sizeof(HeapBlock) & (_segment_size - 1);
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}
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   261
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// Finds the next free heapblock. If the current one is free, that it returned
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   263
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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  assert(b == NULL || !b->free(), "must be in use or at end of heap");
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   268
  return (b == NULL) ? NULL : b->allocated_space();
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}
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   270
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// Returns the first used HeapBlock
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HeapBlock* CodeHeap::first_block() const {
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   273
  if (_next_segment > 0)
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    return block_at(0);
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  return NULL;
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}
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   277
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HeapBlock *CodeHeap::block_start(void *q) const {
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   279
  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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   282
}
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   283
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// Returns the next Heap block an offset into one
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   285
HeapBlock* CodeHeap::next_block(HeapBlock *b) const {
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   286
  if (b == NULL) return NULL;
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   287
  size_t i = segment_for(b) + b->length();
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   288
  if (i < _next_segment)
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   289
    return block_at(i);
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   290
  return NULL;
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   291
}
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   292
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   293
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   294
// Returns current capacity
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   295
size_t CodeHeap::capacity() const {
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   296
  return _memory.committed_size();
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   297
}
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   298
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   299
size_t CodeHeap::max_capacity() const {
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   300
  return _memory.reserved_size();
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   301
}
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   302
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   303
size_t CodeHeap::allocated_capacity() const {
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   304
  // Start with the committed size in _memory;
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   305
  size_t l = _memory.committed_size();
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   306
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   307
  // Subtract the committed, but unused, segments
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   308
  l -= size(_number_of_committed_segments - _next_segment);
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   309
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   310
  // Subtract the size of the freelist
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   311
  l -= size(_free_segments);
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   312
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   313
  return l;
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   314
}
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   315
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   316
// Free list management
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   317
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   318
FreeBlock *CodeHeap::following_block(FreeBlock *b) {
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   319
  return (FreeBlock*)(((address)b) + _segment_size * b->length());
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   320
}
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   321
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   322
// Inserts block b after a
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   323
void CodeHeap::insert_after(FreeBlock* a, FreeBlock* b) {
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   324
  assert(a != NULL && b != NULL, "must be real pointers");
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   325
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   326
  // Link b into the list after a
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   327
  b->set_link(a->link());
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   328
  a->set_link(b);
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   329
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   330
  // See if we can merge blocks
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   331
  merge_right(b); // Try to make b bigger
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   332
  merge_right(a); // Try to make a include b
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   333
}
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   334
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   335
// Try to merge this block with the following block
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   336
void CodeHeap::merge_right(FreeBlock *a) {
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   337
  assert(a->free(), "must be a free block");
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   338
  if (following_block(a) == a->link()) {
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   339
    assert(a->link() != NULL && a->link()->free(), "must be free too");
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   340
    // Update block a to include the following block
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   341
    a->set_length(a->length() + a->link()->length());
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   342
    a->set_link(a->link()->link());
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   343
    // Update find_start map
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   344
    size_t beg = segment_for(a);
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   345
    mark_segmap_as_used(beg, beg + a->length());
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   346
  }
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   347
}
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   348
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   349
void CodeHeap::add_to_freelist(HeapBlock *a) {
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   350
  FreeBlock* b = (FreeBlock*)a;
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   351
  assert(b != _freelist, "cannot be removed twice");
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   352
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   353
  // Mark as free and update free space count
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   354
  _free_segments += b->length();
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   355
  b->set_free();
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   356
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   357
  // First element in list?
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   358
  if (_freelist == NULL) {
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   359
    _freelist = b;
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   360
    b->set_link(NULL);
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   361
    return;
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diff changeset
   362
  }
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   363
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diff changeset
   364
  // Scan for right place to put into list. List
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   365
  // is sorted by increasing addresseses
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diff changeset
   366
  FreeBlock* prev = NULL;
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diff changeset
   367
  FreeBlock* cur  = _freelist;
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diff changeset
   368
  while(cur != NULL && cur < b) {
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   369
    assert(prev == NULL || prev < cur, "must be ordered");
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   370
    prev = cur;
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diff changeset
   371
    cur  = cur->link();
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diff changeset
   372
  }
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   373
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   374
  assert( (prev == NULL && b < _freelist) ||
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   375
          (prev < b && (cur == NULL || b < cur)), "list must be ordered");
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   376
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diff changeset
   377
  if (prev == NULL) {
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diff changeset
   378
    // Insert first in list
489c9b5090e2 Initial load
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   379
    b->set_link(_freelist);
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   380
    _freelist = b;
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diff changeset
   381
    merge_right(_freelist);
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diff changeset
   382
  } else {
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diff changeset
   383
    insert_after(prev, b);
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diff changeset
   384
  }
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diff changeset
   385
}
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   386
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   387
// Search freelist for an entry on the list with the best fit
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   388
// Return NULL if no one was found
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   389
FreeBlock* CodeHeap::search_freelist(size_t length) {
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   390
  FreeBlock *best_block = NULL;
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diff changeset
   391
  FreeBlock *best_prev  = NULL;
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   392
  size_t best_length = 0;
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   393
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diff changeset
   394
  // Search for smallest block which is bigger than length
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diff changeset
   395
  FreeBlock *prev = NULL;
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parents:
diff changeset
   396
  FreeBlock *cur = _freelist;
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diff changeset
   397
  while(cur != NULL) {
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parents:
diff changeset
   398
    size_t l = cur->length();
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parents:
diff changeset
   399
    if (l >= length && (best_block == NULL || best_length > l)) {
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diff changeset
   400
      // Remember best block, its previous element, and its length
489c9b5090e2 Initial load
duke
parents:
diff changeset
   401
      best_block = cur;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   402
      best_prev  = prev;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   403
      best_length = best_block->length();
489c9b5090e2 Initial load
duke
parents:
diff changeset
   404
    }
489c9b5090e2 Initial load
duke
parents:
diff changeset
   405
489c9b5090e2 Initial load
duke
parents:
diff changeset
   406
    // Next element in list
489c9b5090e2 Initial load
duke
parents:
diff changeset
   407
    prev = cur;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   408
    cur  = cur->link();
489c9b5090e2 Initial load
duke
parents:
diff changeset
   409
  }
489c9b5090e2 Initial load
duke
parents:
diff changeset
   410
489c9b5090e2 Initial load
duke
parents:
diff changeset
   411
  if (best_block == NULL) {
489c9b5090e2 Initial load
duke
parents:
diff changeset
   412
    // None found
489c9b5090e2 Initial load
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parents:
diff changeset
   413
    return NULL;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   414
  }
489c9b5090e2 Initial load
duke
parents:
diff changeset
   415
489c9b5090e2 Initial load
duke
parents:
diff changeset
   416
  assert((best_prev == NULL && _freelist == best_block ) ||
489c9b5090e2 Initial load
duke
parents:
diff changeset
   417
         (best_prev != NULL && best_prev->link() == best_block), "sanity check");
489c9b5090e2 Initial load
duke
parents:
diff changeset
   418
489c9b5090e2 Initial load
duke
parents:
diff changeset
   419
  // Exact (or at least good enough) fit. Remove from list.
489c9b5090e2 Initial load
duke
parents:
diff changeset
   420
  // Don't leave anything on the freelist smaller than CodeCacheMinBlockLength.
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duke
parents:
diff changeset
   421
  if (best_length < length + CodeCacheMinBlockLength) {
489c9b5090e2 Initial load
duke
parents:
diff changeset
   422
    length = best_length;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   423
    if (best_prev == NULL) {
489c9b5090e2 Initial load
duke
parents:
diff changeset
   424
      assert(_freelist == best_block, "sanity check");
489c9b5090e2 Initial load
duke
parents:
diff changeset
   425
      _freelist = _freelist->link();
489c9b5090e2 Initial load
duke
parents:
diff changeset
   426
    } else {
489c9b5090e2 Initial load
duke
parents:
diff changeset
   427
      // Unmap element
489c9b5090e2 Initial load
duke
parents:
diff changeset
   428
      best_prev->set_link(best_block->link());
489c9b5090e2 Initial load
duke
parents:
diff changeset
   429
    }
489c9b5090e2 Initial load
duke
parents:
diff changeset
   430
  } else {
489c9b5090e2 Initial load
duke
parents:
diff changeset
   431
    // Truncate block and return a pointer to the following block
489c9b5090e2 Initial load
duke
parents:
diff changeset
   432
    best_block->set_length(best_length - length);
489c9b5090e2 Initial load
duke
parents:
diff changeset
   433
    best_block = following_block(best_block);
489c9b5090e2 Initial load
duke
parents:
diff changeset
   434
    // Set used bit and length on new block
489c9b5090e2 Initial load
duke
parents:
diff changeset
   435
    size_t beg = segment_for(best_block);
489c9b5090e2 Initial load
duke
parents:
diff changeset
   436
    mark_segmap_as_used(beg, beg + length);
489c9b5090e2 Initial load
duke
parents:
diff changeset
   437
    best_block->set_length(length);
489c9b5090e2 Initial load
duke
parents:
diff changeset
   438
  }
489c9b5090e2 Initial load
duke
parents:
diff changeset
   439
489c9b5090e2 Initial load
duke
parents:
diff changeset
   440
  best_block->set_used();
489c9b5090e2 Initial load
duke
parents:
diff changeset
   441
  _free_segments -= length;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   442
  return best_block;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   443
}
489c9b5090e2 Initial load
duke
parents:
diff changeset
   444
489c9b5090e2 Initial load
duke
parents:
diff changeset
   445
//----------------------------------------------------------------------------
489c9b5090e2 Initial load
duke
parents:
diff changeset
   446
// Non-product code
489c9b5090e2 Initial load
duke
parents:
diff changeset
   447
489c9b5090e2 Initial load
duke
parents:
diff changeset
   448
#ifndef PRODUCT
489c9b5090e2 Initial load
duke
parents:
diff changeset
   449
489c9b5090e2 Initial load
duke
parents:
diff changeset
   450
void CodeHeap::print() {
489c9b5090e2 Initial load
duke
parents:
diff changeset
   451
  tty->print_cr("The Heap");
489c9b5090e2 Initial load
duke
parents:
diff changeset
   452
}
489c9b5090e2 Initial load
duke
parents:
diff changeset
   453
489c9b5090e2 Initial load
duke
parents:
diff changeset
   454
#endif
489c9b5090e2 Initial load
duke
parents:
diff changeset
   455
489c9b5090e2 Initial load
duke
parents:
diff changeset
   456
void CodeHeap::verify() {
489c9b5090e2 Initial load
duke
parents:
diff changeset
   457
  // Count the number of blocks on the freelist, and the amount of space
489c9b5090e2 Initial load
duke
parents:
diff changeset
   458
  // represented.
489c9b5090e2 Initial load
duke
parents:
diff changeset
   459
  int count = 0;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   460
  size_t len = 0;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   461
  for(FreeBlock* b = _freelist; b != NULL; b = b->link()) {
489c9b5090e2 Initial load
duke
parents:
diff changeset
   462
    len += b->length();
489c9b5090e2 Initial load
duke
parents:
diff changeset
   463
    count++;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   464
  }
489c9b5090e2 Initial load
duke
parents:
diff changeset
   465
489c9b5090e2 Initial load
duke
parents:
diff changeset
   466
  // Verify that freelist contains the right amount of free space
489c9b5090e2 Initial load
duke
parents:
diff changeset
   467
  guarantee(len == _free_segments, "wrong freelist");
489c9b5090e2 Initial load
duke
parents:
diff changeset
   468
489c9b5090e2 Initial load
duke
parents:
diff changeset
   469
  // Verify that the number of free blocks is not out of hand.
489c9b5090e2 Initial load
duke
parents:
diff changeset
   470
  static int free_block_threshold = 10000;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   471
  if (count > free_block_threshold) {
489c9b5090e2 Initial load
duke
parents:
diff changeset
   472
    warning("CodeHeap: # of free blocks > %d", free_block_threshold);
489c9b5090e2 Initial load
duke
parents:
diff changeset
   473
    // Double the warning limit
489c9b5090e2 Initial load
duke
parents:
diff changeset
   474
    free_block_threshold *= 2;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   475
  }
489c9b5090e2 Initial load
duke
parents:
diff changeset
   476
489c9b5090e2 Initial load
duke
parents:
diff changeset
   477
  // Verify that the freelist contains the same number of free blocks that is
489c9b5090e2 Initial load
duke
parents:
diff changeset
   478
  // found on the full list.
489c9b5090e2 Initial load
duke
parents:
diff changeset
   479
  for(HeapBlock *h = first_block(); h != NULL; h = next_block(h)) {
489c9b5090e2 Initial load
duke
parents:
diff changeset
   480
    if (h->free()) count--;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   481
  }
489c9b5090e2 Initial load
duke
parents:
diff changeset
   482
  guarantee(count == 0, "missing free blocks");
489c9b5090e2 Initial load
duke
parents:
diff changeset
   483
}