rev 6670 : fast reclaim main patch

   1 /*
   2  * Copyright (c) 2014, 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.
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  24 
  25 #ifndef SHARE_VM_GC_IMPLEMENTATION_G1_G1PARSCANTHREADSTATE_INLINE_HPP
  26 #define SHARE_VM_GC_IMPLEMENTATION_G1_G1PARSCANTHREADSTATE_INLINE_HPP
  27 
  28 #include "gc_implementation/g1/g1ParScanThreadState.hpp"
  29 #include "gc_implementation/g1/g1RemSet.inline.hpp"
  30 #include "oops/oop.inline.hpp"
  31 
  32 template <class T> inline void G1ParScanThreadState::immediate_rs_update(HeapRegion* from, T* p, int tid) {
  33   if (!from->is_survivor()) {
  34     _g1_rem->par_write_ref(from, p, tid);
  35   }
  36 }
  37 
  38 template <class T> void G1ParScanThreadState::update_rs(HeapRegion* from, T* p, int tid) {
  39   if (G1DeferredRSUpdate) {
  40     deferred_rs_update(from, p, tid);
  41   } else {
  42     immediate_rs_update(from, p, tid);
  43   }
  44 }
  45 
  46 template <class T> void G1ParScanThreadState::do_oop_evac(T* p, HeapRegion* from) {
  47   assert(!oopDesc::is_null(oopDesc::load_decode_heap_oop(p)),
  48          "Reference should not be NULL here as such are never pushed to the task queue.");
  49   oop obj = oopDesc::load_decode_heap_oop_not_null(p);
  50 
  51   // Although we never intentionally push references outside of the collection
  52   // set, due to (benign) races in the claim mechanism during RSet scanning more
  53   // than one thread might claim the same card. So the same card may be
  54   // processed multiple times. So redo this check.
  55   if (_g1h->is_in_cset_or_humongous(obj)) {
  56     oop forwardee;
  57     if (obj->is_forwarded()) {
  58       forwardee = obj->forwardee();
  59     } else {
  60       forwardee = copy_to_survivor_space(obj);
  61     }
  62     if (forwardee != NULL) {
  63       oopDesc::encode_store_heap_oop(p, forwardee);
  64     }
  65   }
  66 
  67   assert(obj != NULL, "Must be");
  68   update_rs(from, p, queue_num());
  69 }
  70 
  71 inline void G1ParScanThreadState::do_oop_partial_array(oop* p) {
  72   assert(has_partial_array_mask(p), "invariant");
  73   oop from_obj = clear_partial_array_mask(p);
  74 
  75   assert(Universe::heap()->is_in_reserved(from_obj), "must be in heap.");
  76   assert(from_obj->is_objArray(), "must be obj array");
  77   objArrayOop from_obj_array = objArrayOop(from_obj);
  78   // The from-space object contains the real length.
  79   int length                 = from_obj_array->length();
  80 
  81   assert(from_obj->is_forwarded(), "must be forwarded");
  82   oop to_obj                 = from_obj->forwardee();
  83   assert(from_obj != to_obj, "should not be chunking self-forwarded objects");
  84   objArrayOop to_obj_array   = objArrayOop(to_obj);
  85   // We keep track of the next start index in the length field of the
  86   // to-space object.
  87   int next_index             = to_obj_array->length();
  88   assert(0 <= next_index && next_index < length,
  89          err_msg("invariant, next index: %d, length: %d", next_index, length));
  90 
  91   int start                  = next_index;
  92   int end                    = length;
  93   int remainder              = end - start;
  94   // We'll try not to push a range that's smaller than ParGCArrayScanChunk.
  95   if (remainder > 2 * ParGCArrayScanChunk) {
  96     end = start + ParGCArrayScanChunk;
  97     to_obj_array->set_length(end);
  98     // Push the remainder before we process the range in case another
  99     // worker has run out of things to do and can steal it.
 100     oop* from_obj_p = set_partial_array_mask(from_obj);
 101     push_on_queue(from_obj_p);
 102   } else {
 103     assert(length == end, "sanity");
 104     // We'll process the final range for this object. Restore the length
 105     // so that the heap remains parsable in case of evacuation failure.
 106     to_obj_array->set_length(end);
 107   }
 108   _scanner.set_region(_g1h->heap_region_containing_raw(to_obj));
 109   // Process indexes [start,end). It will also process the header
 110   // along with the first chunk (i.e., the chunk with start == 0).
 111   // Note that at this point the length field of to_obj_array is not
 112   // correct given that we are using it to keep track of the next
 113   // start index. oop_iterate_range() (thankfully!) ignores the length
 114   // field and only relies on the start / end parameters.  It does
 115   // however return the size of the object which will be incorrect. So
 116   // we have to ignore it even if we wanted to use it.
 117   to_obj_array->oop_iterate_range(&_scanner, start, end);
 118 }
 119 
 120 template <class T> inline void G1ParScanThreadState::deal_with_reference(T* ref_to_scan) {
 121   if (!has_partial_array_mask(ref_to_scan)) {
 122     // Note: we can use "raw" versions of "region_containing" because
 123     // "obj_to_scan" is definitely in the heap, and is not in a
 124     // humongous region.
 125     HeapRegion* r = _g1h->heap_region_containing_raw(ref_to_scan);
 126     do_oop_evac(ref_to_scan, r);
 127   } else {
 128     do_oop_partial_array((oop*)ref_to_scan);
 129   }
 130 }
 131 
 132 inline void G1ParScanThreadState::dispatch_reference(StarTask ref) {
 133   assert(verify_task(ref), "sanity");
 134   if (ref.is_narrow()) {
 135     deal_with_reference((narrowOop*)ref);
 136   } else {
 137     deal_with_reference((oop*)ref);
 138   }
 139 }
 140 
 141 void G1ParScanThreadState::steal_and_trim_queue(RefToScanQueueSet *task_queues) {
 142   StarTask stolen_task;
 143   while (task_queues->steal(queue_num(), hash_seed(), stolen_task)) {
 144     assert(verify_task(stolen_task), "sanity");
 145     dispatch_reference(stolen_task);
 146 
 147     // We've just processed a reference and we might have made
 148     // available new entries on the queues. So we have to make sure
 149     // we drain the queues as necessary.
 150     trim_queue();
 151   }
 152 }
 153 
 154 #endif /* SHARE_VM_GC_IMPLEMENTATION_G1_G1PARSCANTHREADSTATE_INLINE_HPP */
 155 
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