rev 59232 : [mq]: scan_task
rev 59233 : [mq]: sjohanss_review

   1 /*
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   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
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  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).
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  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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  24 
  25 #ifndef SHARE_GC_G1_G1PARSCANTHREADSTATE_INLINE_HPP
  26 #define SHARE_GC_G1_G1PARSCANTHREADSTATE_INLINE_HPP
  27 
  28 #include "gc/g1/g1CollectedHeap.inline.hpp"
  29 #include "gc/g1/g1OopStarChunkedList.inline.hpp"
  30 #include "gc/g1/g1ParScanThreadState.hpp"
  31 #include "gc/g1/g1RemSet.hpp"
  32 #include "oops/access.inline.hpp"
  33 #include "oops/oop.inline.hpp"
  34 
  35 template <class T> void G1ParScanThreadState::do_oop_evac(T* p) {
  36   // Reference should not be NULL here as such are never pushed to the task queue.
  37   oop obj = RawAccess<IS_NOT_NULL>::oop_load(p);
  38 
  39   // Although we never intentionally push references outside of the collection
  40   // set, due to (benign) races in the claim mechanism during RSet scanning more
  41   // than one thread might claim the same card. So the same card may be
  42   // processed multiple times, and so we might get references into old gen here.
  43   // So we need to redo this check.
  44   const G1HeapRegionAttr region_attr = _g1h->region_attr(obj);
  45   // References pushed onto the work stack should never point to a humongous region
  46   // as they are not added to the collection set due to above precondition.
  47   assert(!region_attr.is_humongous(),
  48          "Obj " PTR_FORMAT " should not refer to humongous region %u from " PTR_FORMAT,
  49          p2i(obj), _g1h->addr_to_region(cast_from_oop<HeapWord*>(obj)), p2i(p));
  50 
  51   if (!region_attr.is_in_cset()) {
  52     // In this case somebody else already did all the work.
  53     return;
  54   }
  55 
  56   markWord m = obj->mark_raw();
  57   if (m.is_marked()) {
  58     obj = (oop) m.decode_pointer();
  59   } else {
  60     obj = copy_to_survivor_space(region_attr, obj, m);
  61   }
  62   RawAccess<IS_NOT_NULL>::oop_store(p, obj);
  63 
  64   assert(obj != NULL, "Must be");
  65   if (HeapRegion::is_in_same_region(p, obj)) {
  66     return;
  67   }
  68   HeapRegion* from = _g1h->heap_region_containing(p);
  69   if (!from->is_young()) {
  70     enqueue_card_if_tracked(_g1h->region_attr(obj), p, obj);
  71   }
  72 }
  73 
  74 inline void G1ParScanThreadState::push_on_queue(ScannerTask task) {
  75   verify_task(task);
  76   _task_queue->push(task);
  77 }
  78 
  79 inline void G1ParScanThreadState::do_partial_array(PartialArrayScanTask task) {
  80   oop from_obj = task.to_source_array();

  81 
  82   assert(_g1h->is_in_reserved(from_obj), "must be in heap.");
  83   assert(from_obj->is_objArray(), "must be obj array");
  84   objArrayOop from_obj_array = objArrayOop(from_obj);
  85   // The from-space object contains the real length.
  86   int length                 = from_obj_array->length();
  87 
  88   assert(from_obj->is_forwarded(), "must be forwarded");
  89   oop to_obj                 = from_obj->forwardee();
  90   assert(from_obj != to_obj, "should not be chunking self-forwarded objects");
  91   objArrayOop to_obj_array   = objArrayOop(to_obj);
  92   // We keep track of the next start index in the length field of the
  93   // to-space object.
  94   int next_index             = to_obj_array->length();
  95   assert(0 <= next_index && next_index < length,
  96          "invariant, next index: %d, length: %d", next_index, length);
  97 
  98   int start                  = next_index;
  99   int end                    = length;
 100   int remainder              = end - start;
 101   // We'll try not to push a range that's smaller than ParGCArrayScanChunk.
 102   if (remainder > 2 * ParGCArrayScanChunk) {
 103     end = start + ParGCArrayScanChunk;
 104     to_obj_array->set_length(end);
 105     // Push the remainder before we process the range in case another
 106     // worker has run out of things to do and can steal it.
 107     push_on_queue(ScannerTask(PartialArrayScanTask(from_obj)));

 108   } else {
 109     assert(length == end, "sanity");
 110     // We'll process the final range for this object. Restore the length
 111     // so that the heap remains parsable in case of evacuation failure.
 112     to_obj_array->set_length(end);
 113   }
 114 
 115   HeapRegion* hr = _g1h->heap_region_containing(to_obj);
 116   G1ScanInYoungSetter x(&_scanner, hr->is_young());
 117   // Process indexes [start,end). It will also process the header
 118   // along with the first chunk (i.e., the chunk with start == 0).
 119   // Note that at this point the length field of to_obj_array is not
 120   // correct given that we are using it to keep track of the next
 121   // start index. oop_iterate_range() (thankfully!) ignores the length
 122   // field and only relies on the start / end parameters.  It does
 123   // however return the size of the object which will be incorrect. So
 124   // we have to ignore it even if we wanted to use it.
 125   to_obj_array->oop_iterate_range(&_scanner, start, end);
 126 }
 127 
 128 inline void G1ParScanThreadState::dispatch_task(ScannerTask task) {
 129   verify_task(task);
 130   if (task.is_narrow_oop_ptr()) {
 131     do_oop_evac(task.to_narrow_oop_ptr());
 132   } else if (task.is_oop_ptr()) {
 133     do_oop_evac(task.to_oop_ptr());
 134   } else {
 135     do_partial_array(task.to_partial_array_task());
 136   }
 137 }
 138 
 139 void G1ParScanThreadState::steal_and_trim_queue(ScannerTasksQueueSet *task_queues) {
 140   ScannerTask stolen_task;














 141   while (task_queues->steal(_worker_id, stolen_task)) {
 142     dispatch_task(stolen_task);

 143 
 144     // We've just processed a task and we might have made
 145     // available new entries on the queues. So we have to make sure
 146     // we drain the queues as necessary.
 147     trim_queue();
 148   }
 149 }
 150 
 151 inline bool G1ParScanThreadState::needs_partial_trimming() const {
 152   return !_task_queue->overflow_empty() ||
 153          (_task_queue->size() > _stack_trim_upper_threshold);
 154 }
 155 
 156 inline bool G1ParScanThreadState::is_partially_trimmed() const {
 157   return _task_queue->overflow_empty() &&
 158          (_task_queue->size() <= _stack_trim_lower_threshold);
 159 }
 160 
 161 inline void G1ParScanThreadState::trim_queue_to_threshold(uint threshold) {
 162   ScannerTask task;
 163   // Drain the overflow stack first, so other threads can potentially steal.
 164   while (_task_queue->pop_overflow(task)) {
 165     if (!_task_queue->try_push_to_taskqueue(task)) {
 166       dispatch_task(task);
 167     }
 168   }
 169 
 170   while (_task_queue->pop_local(task, threshold)) {
 171     dispatch_task(task);
 172   }
 173 }
 174 
 175 inline void G1ParScanThreadState::trim_queue_partially() {
 176   if (!needs_partial_trimming()) {
 177     return;
 178   }
 179 
 180   const Ticks start = Ticks::now();
 181   do {
 182     trim_queue_to_threshold(_stack_trim_lower_threshold);
 183   } while (!is_partially_trimmed());
 184   _trim_ticks += Ticks::now() - start;
 185 }
 186 
 187 inline Tickspan G1ParScanThreadState::trim_ticks() const {
 188   return _trim_ticks;
 189 }
 190 
 191 inline void G1ParScanThreadState::reset_trim_ticks() {
 192   _trim_ticks = Tickspan();
 193 }
 194 
 195 template <typename T>
 196 inline void G1ParScanThreadState::remember_root_into_optional_region(T* p) {
 197   oop o = RawAccess<IS_NOT_NULL>::oop_load(p);
 198   uint index = _g1h->heap_region_containing(o)->index_in_opt_cset();
 199   assert(index < _num_optional_regions,
 200          "Trying to access optional region idx %u beyond " SIZE_FORMAT, index, _num_optional_regions);
 201   _oops_into_optional_regions[index].push_root(p);
 202 }
 203 
 204 template <typename T>
 205 inline void G1ParScanThreadState::remember_reference_into_optional_region(T* p) {
 206   oop o = RawAccess<IS_NOT_NULL>::oop_load(p);
 207   uint index = _g1h->heap_region_containing(o)->index_in_opt_cset();
 208   assert(index < _num_optional_regions,
 209          "Trying to access optional region idx %u beyond " SIZE_FORMAT, index, _num_optional_regions);
 210   _oops_into_optional_regions[index].push_oop(p);
 211   verify_task(p);
 212 }
 213 
 214 G1OopStarChunkedList* G1ParScanThreadState::oops_into_optional_region(const HeapRegion* hr) {
 215   assert(hr->index_in_opt_cset() < _num_optional_regions,
 216          "Trying to access optional region idx %u beyond " SIZE_FORMAT " " HR_FORMAT,
 217          hr->index_in_opt_cset(), _num_optional_regions, HR_FORMAT_PARAMS(hr));
 218   return &_oops_into_optional_regions[hr->index_in_opt_cset()];
 219 }
 220 
 221 void G1ParScanThreadState::initialize_numa_stats() {
 222   if (_numa->is_enabled()) {
 223     LogTarget(Info, gc, heap, numa) lt;
 224 
 225     if (lt.is_enabled()) {
 226       uint num_nodes = _numa->num_active_nodes();
 227       // Record only if there are multiple active nodes.
 228       _obj_alloc_stat = NEW_C_HEAP_ARRAY(size_t, num_nodes, mtGC);
 229       memset(_obj_alloc_stat, 0, sizeof(size_t) * num_nodes);
 230     }
 231   }
 232 }
 233 
 234 void G1ParScanThreadState::flush_numa_stats() {
 235   if (_obj_alloc_stat != NULL) {
 236     uint node_index = _numa->index_of_current_thread();
 237     _numa->copy_statistics(G1NUMAStats::LocalObjProcessAtCopyToSurv, node_index, _obj_alloc_stat);
 238   }
 239 }
 240 
 241 void G1ParScanThreadState::update_numa_stats(uint node_index) {
 242   if (_obj_alloc_stat != NULL) {
 243     _obj_alloc_stat[node_index]++;
 244   }
 245 }
 246 
 247 #endif // SHARE_GC_G1_G1PARSCANTHREADSTATE_INLINE_HPP
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