Thu, 11 Dec 2008 12:05:08 -0800
6578152: fill_region_with_object has usability and safety issues
Reviewed-by: apetrusenko, ysr
duke@435 | 1 | /* |
duke@435 | 2 | * Copyright 1999-2007 Sun Microsystems, Inc. All Rights Reserved. |
duke@435 | 3 | * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
duke@435 | 4 | * |
duke@435 | 5 | * This code is free software; you can redistribute it and/or modify it |
duke@435 | 6 | * under the terms of the GNU General Public License version 2 only, as |
duke@435 | 7 | * published by the Free Software Foundation. |
duke@435 | 8 | * |
duke@435 | 9 | * This code is distributed in the hope that it will be useful, but WITHOUT |
duke@435 | 10 | * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
duke@435 | 11 | * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
duke@435 | 12 | * version 2 for more details (a copy is included in the LICENSE file that |
duke@435 | 13 | * accompanied this code). |
duke@435 | 14 | * |
duke@435 | 15 | * You should have received a copy of the GNU General Public License version |
duke@435 | 16 | * 2 along with this work; if not, write to the Free Software Foundation, |
duke@435 | 17 | * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
duke@435 | 18 | * |
duke@435 | 19 | * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, |
duke@435 | 20 | * CA 95054 USA or visit www.sun.com if you need additional information or |
duke@435 | 21 | * have any questions. |
duke@435 | 22 | * |
duke@435 | 23 | */ |
duke@435 | 24 | |
duke@435 | 25 | inline HeapWord* ThreadLocalAllocBuffer::allocate(size_t size) { |
duke@435 | 26 | invariants(); |
duke@435 | 27 | HeapWord* obj = top(); |
duke@435 | 28 | if (pointer_delta(end(), obj) >= size) { |
duke@435 | 29 | // successful thread-local allocation |
duke@435 | 30 | |
duke@435 | 31 | DEBUG_ONLY(Copy::fill_to_words(obj, size, badHeapWordVal)); |
duke@435 | 32 | // This addition is safe because we know that top is |
duke@435 | 33 | // at least size below end, so the add can't wrap. |
duke@435 | 34 | set_top(obj + size); |
duke@435 | 35 | |
duke@435 | 36 | invariants(); |
duke@435 | 37 | return obj; |
duke@435 | 38 | } |
duke@435 | 39 | return NULL; |
duke@435 | 40 | } |
duke@435 | 41 | |
duke@435 | 42 | inline size_t ThreadLocalAllocBuffer::compute_size(size_t obj_size) { |
duke@435 | 43 | const size_t aligned_obj_size = align_object_size(obj_size); |
duke@435 | 44 | |
duke@435 | 45 | // Compute the size for the new TLAB. |
duke@435 | 46 | // The "last" tlab may be smaller to reduce fragmentation. |
duke@435 | 47 | // unsafe_max_tlab_alloc is just a hint. |
duke@435 | 48 | const size_t available_size = Universe::heap()->unsafe_max_tlab_alloc(myThread()) / |
duke@435 | 49 | HeapWordSize; |
duke@435 | 50 | size_t new_tlab_size = MIN2(available_size, desired_size() + aligned_obj_size); |
duke@435 | 51 | |
duke@435 | 52 | // Make sure there's enough room for object and filler int[]. |
duke@435 | 53 | const size_t obj_plus_filler_size = aligned_obj_size + alignment_reserve(); |
duke@435 | 54 | if (new_tlab_size < obj_plus_filler_size) { |
duke@435 | 55 | // If there isn't enough room for the allocation, return failure. |
duke@435 | 56 | if (PrintTLAB && Verbose) { |
duke@435 | 57 | gclog_or_tty->print_cr("ThreadLocalAllocBuffer::compute_size(" SIZE_FORMAT ")" |
duke@435 | 58 | " returns failure", |
duke@435 | 59 | obj_size); |
duke@435 | 60 | } |
duke@435 | 61 | return 0; |
duke@435 | 62 | } |
duke@435 | 63 | if (PrintTLAB && Verbose) { |
duke@435 | 64 | gclog_or_tty->print_cr("ThreadLocalAllocBuffer::compute_size(" SIZE_FORMAT ")" |
duke@435 | 65 | " returns " SIZE_FORMAT, |
duke@435 | 66 | obj_size, new_tlab_size); |
duke@435 | 67 | } |
duke@435 | 68 | return new_tlab_size; |
duke@435 | 69 | } |
duke@435 | 70 | |
duke@435 | 71 | |
duke@435 | 72 | void ThreadLocalAllocBuffer::record_slow_allocation(size_t obj_size) { |
duke@435 | 73 | // Raise size required to bypass TLAB next time. Why? Else there's |
duke@435 | 74 | // a risk that a thread that repeatedly allocates objects of one |
duke@435 | 75 | // size will get stuck on this slow path. |
duke@435 | 76 | |
duke@435 | 77 | set_refill_waste_limit(refill_waste_limit() + refill_waste_limit_increment()); |
duke@435 | 78 | |
duke@435 | 79 | _slow_allocations++; |
duke@435 | 80 | |
duke@435 | 81 | if (PrintTLAB && Verbose) { |
duke@435 | 82 | Thread* thrd = myThread(); |
duke@435 | 83 | gclog_or_tty->print("TLAB: %s thread: "INTPTR_FORMAT" [id: %2d]" |
duke@435 | 84 | " obj: "SIZE_FORMAT |
duke@435 | 85 | " free: "SIZE_FORMAT |
duke@435 | 86 | " waste: "SIZE_FORMAT"\n", |
duke@435 | 87 | "slow", thrd, thrd->osthread()->thread_id(), |
duke@435 | 88 | obj_size, free(), refill_waste_limit()); |
duke@435 | 89 | } |
duke@435 | 90 | } |