view src/share/vm/memory/threadLocalAllocBuffer.inline.hpp @ 3917:eca1193ca245

4965777: GC changes to support use of discovered field for pending references Summary: If and when the reference handler thread is able to use the discovered field to link reference objects in its pending list, so will GC. In that case, GC will scan through this field once a reference object has been placed on the pending list, but not scan that field before that stage, as the field is used by the concurrent GC thread to link discovered objects. When ReferenceHandleR thread does not use the discovered field for the purpose of linking the elements in the pending list, as would be the case in older JDKs, the JVM will fall back to the old behaviour of using the next field for that purpose. Reviewed-by: jcoomes, mchung, stefank
author ysr
date Wed, 07 Sep 2011 13:55:42 -0700
parents c760f78e0a53
children 78bbf4d43a14
line wrap: on
line source

/*
 * Copyright (c) 1999, 2010, Oracle and/or its affiliates. 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 *
 */

#ifndef SHARE_VM_MEMORY_THREADLOCALALLOCBUFFER_INLINE_HPP
#define SHARE_VM_MEMORY_THREADLOCALALLOCBUFFER_INLINE_HPP

#include "gc_interface/collectedHeap.hpp"
#include "memory/threadLocalAllocBuffer.hpp"
#include "runtime/atomic.hpp"
#include "runtime/thread.hpp"
#include "utilities/copy.hpp"

inline HeapWord* ThreadLocalAllocBuffer::allocate(size_t size) {
  invariants();
  HeapWord* obj = top();
  if (pointer_delta(end(), obj) >= size) {
    // successful thread-local allocation
#ifdef ASSERT
    // Skip mangling the space corresponding to the object header to
    // ensure that the returned space is not considered parsable by
    // any concurrent GC thread.
    size_t hdr_size = oopDesc::header_size();
    Copy::fill_to_words(obj + hdr_size, size - hdr_size, badHeapWordVal);
#endif // ASSERT
    // This addition is safe because we know that top is
    // at least size below end, so the add can't wrap.
    set_top(obj + size);

    invariants();
    return obj;
  }
  return NULL;
}

inline size_t ThreadLocalAllocBuffer::compute_size(size_t obj_size) {
  const size_t aligned_obj_size = align_object_size(obj_size);

  // Compute the size for the new TLAB.
  // The "last" tlab may be smaller to reduce fragmentation.
  // unsafe_max_tlab_alloc is just a hint.
  const size_t available_size = Universe::heap()->unsafe_max_tlab_alloc(myThread()) /
                                                  HeapWordSize;
  size_t new_tlab_size = MIN2(available_size, desired_size() + aligned_obj_size);

  // Make sure there's enough room for object and filler int[].
  const size_t obj_plus_filler_size = aligned_obj_size + alignment_reserve();
  if (new_tlab_size < obj_plus_filler_size) {
    // If there isn't enough room for the allocation, return failure.
    if (PrintTLAB && Verbose) {
      gclog_or_tty->print_cr("ThreadLocalAllocBuffer::compute_size(" SIZE_FORMAT ")"
                    " returns failure",
                    obj_size);
    }
    return 0;
  }
  if (PrintTLAB && Verbose) {
    gclog_or_tty->print_cr("ThreadLocalAllocBuffer::compute_size(" SIZE_FORMAT ")"
                  " returns " SIZE_FORMAT,
                  obj_size, new_tlab_size);
  }
  return new_tlab_size;
}


void ThreadLocalAllocBuffer::record_slow_allocation(size_t obj_size) {
  // Raise size required to bypass TLAB next time. Why? Else there's
  // a risk that a thread that repeatedly allocates objects of one
  // size will get stuck on this slow path.

  set_refill_waste_limit(refill_waste_limit() + refill_waste_limit_increment());

  _slow_allocations++;

  if (PrintTLAB && Verbose) {
    Thread* thrd = myThread();
    gclog_or_tty->print("TLAB: %s thread: "INTPTR_FORMAT" [id: %2d]"
                        " obj: "SIZE_FORMAT
                        " free: "SIZE_FORMAT
                        " waste: "SIZE_FORMAT"\n",
                        "slow", thrd, thrd->osthread()->thread_id(),
                        obj_size, free(), refill_waste_limit());
  }
}

#endif // SHARE_VM_MEMORY_THREADLOCALALLOCBUFFER_INLINE_HPP