1 /*
   2  * Copyright (c) 1999, 2009, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  *
  23  */
  24 
  25 inline HeapWord* ThreadLocalAllocBuffer::allocate(size_t size) {
  26   invariants();
  27   HeapWord* obj = top();
  28   if (pointer_delta(end(), obj) >= size) {
  29     // successful thread-local allocation
  30 #ifdef ASSERT
  31     // Skip mangling the space corresponding to the object header to
  32     // ensure that the returned space is not considered parsable by
  33     // any concurrent GC thread.
  34     size_t hdr_size = oopDesc::header_size();
  35     Copy::fill_to_words(obj + hdr_size, size - hdr_size, badHeapWordVal);
  36 #endif // ASSERT
  37     // This addition is safe because we know that top is
  38     // at least size below end, so the add can't wrap.
  39     set_top(obj + size);
  40 
  41     invariants();
  42     return obj;
  43   }
  44   return NULL;
  45 }
  46 
  47 inline size_t ThreadLocalAllocBuffer::compute_size(size_t obj_size) {
  48   const size_t aligned_obj_size = align_object_size(obj_size);
  49 
  50   // Compute the size for the new TLAB.
  51   // The "last" tlab may be smaller to reduce fragmentation.
  52   // unsafe_max_tlab_alloc is just a hint.
  53   const size_t available_size = Universe::heap()->unsafe_max_tlab_alloc(myThread()) /
  54                                                   HeapWordSize;
  55   size_t new_tlab_size = MIN2(available_size, desired_size() + aligned_obj_size);
  56 
  57   // Make sure there's enough room for object and filler int[].
  58   const size_t obj_plus_filler_size = aligned_obj_size + alignment_reserve();
  59   if (new_tlab_size < obj_plus_filler_size) {
  60     // If there isn't enough room for the allocation, return failure.
  61     if (PrintTLAB && Verbose) {
  62       gclog_or_tty->print_cr("ThreadLocalAllocBuffer::compute_size(" SIZE_FORMAT ")"
  63                     " returns failure",
  64                     obj_size);
  65     }
  66     return 0;
  67   }
  68   if (PrintTLAB && Verbose) {
  69     gclog_or_tty->print_cr("ThreadLocalAllocBuffer::compute_size(" SIZE_FORMAT ")"
  70                   " returns " SIZE_FORMAT,
  71                   obj_size, new_tlab_size);
  72   }
  73   return new_tlab_size;
  74 }
  75 
  76 
  77 void ThreadLocalAllocBuffer::record_slow_allocation(size_t obj_size) {
  78   // Raise size required to bypass TLAB next time. Why? Else there's
  79   // a risk that a thread that repeatedly allocates objects of one
  80   // size will get stuck on this slow path.
  81 
  82   set_refill_waste_limit(refill_waste_limit() + refill_waste_limit_increment());
  83 
  84   _slow_allocations++;
  85 
  86   if (PrintTLAB && Verbose) {
  87     Thread* thrd = myThread();
  88     gclog_or_tty->print("TLAB: %s thread: "INTPTR_FORMAT" [id: %2d]"
  89                         " obj: "SIZE_FORMAT
  90                         " free: "SIZE_FORMAT
  91                         " waste: "SIZE_FORMAT"\n",
  92                         "slow", thrd, thrd->osthread()->thread_id(),
  93                         obj_size, free(), refill_waste_limit());
  94   }
  95 }