Thu, 27 May 2010 18:01:56 -0700
6916623: Align object to 16 bytes to use Compressed Oops with java heap up to 64Gb
Summary: Added new product ObjectAlignmentInBytes flag to control object alignment.
Reviewed-by: twisti, ysr, iveresov
1 /*
2 * Copyright 1999-2009 Sun Microsystems, Inc. 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
20 * CA 95054 USA or visit www.sun.com if you need additional information or
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23 */
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);
41 invariants();
42 return obj;
43 }
44 return NULL;
45 }
47 inline size_t ThreadLocalAllocBuffer::compute_size(size_t obj_size) {
48 const size_t aligned_obj_size = align_object_size(obj_size);
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);
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 }
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.
82 set_refill_waste_limit(refill_waste_limit() + refill_waste_limit_increment());
84 _slow_allocations++;
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 }