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src/share/vm/gc/g1/g1EvacStats.cpp

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   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 #include "precompiled.hpp"
  26 #include "gc/g1/g1EvacStats.hpp"
  27 #include "gc/shared/gcId.hpp"

  28 #include "trace/tracing.hpp"
  29 
  30 void G1EvacStats::adjust_desired_plab_sz() {
  31   if (PrintPLAB) {
  32     gclog_or_tty->print(" (allocated = " SIZE_FORMAT " wasted = " SIZE_FORMAT " "
  33                         "unused = " SIZE_FORMAT " used = " SIZE_FORMAT " "
  34                         "undo_waste = " SIZE_FORMAT " region_end_waste = " SIZE_FORMAT " "
  35                         "regions filled = %u direct_allocated = " SIZE_FORMAT " "
  36                         "failure_used = " SIZE_FORMAT " failure_waste = " SIZE_FORMAT ") ",
  37                         _allocated, _wasted, _unused, used(), _undo_wasted, _region_end_waste,
  38                         _regions_filled, _direct_allocated, _failure_used, _failure_waste);



  39   }
  40 
  41   if (ResizePLAB) {
  42 
  43     assert(is_object_aligned(max_size()) && min_size() <= max_size(),
  44            "PLAB clipping computation may be incorrect");
  45 
  46     if (_allocated == 0) {
  47       assert((_unused == 0),
  48              "Inconsistency in PLAB stats: "
  49              "_allocated: " SIZE_FORMAT ", "
  50              "_wasted: " SIZE_FORMAT ", "
  51              "_region_end_waste: " SIZE_FORMAT ", "
  52              "_unused: " SIZE_FORMAT ", "
  53              "_used  : " SIZE_FORMAT,
  54              _allocated, _wasted, _region_end_waste, _unused, used());
  55       _allocated = 1;
  56     }
  57     // The size of the PLAB caps the amount of space that can be wasted at the
  58     // end of the collection. In the worst case the last PLAB could be completely
  59     // empty.
  60     // This allows us to calculate the new PLAB size to achieve the
  61     // TargetPLABWastePct given the latest memory usage and that the last buffer
  62     // will be G1LastPLABAverageOccupancy full.


  86     //
  87     // We need to cover overflow when calculating the amount of space actually used
  88     // by objects in PLABs when subtracting the region end waste.
  89     // Region end waste may be higher than actual allocation. This may occur if many
  90     // threads do not allocate anything but a few rather large objects. In this
  91     // degenerate case the PLAB size would simply quickly tend to minimum PLAB size,
  92     // which is an okay reaction.
  93     size_t const used_for_waste_calculation = used() > _region_end_waste ? used() - _region_end_waste : 0;
  94 
  95     size_t const total_waste_allowed = used_for_waste_calculation * TargetPLABWastePct;
  96     size_t const cur_plab_sz = (size_t)((double)total_waste_allowed / G1LastPLABAverageOccupancy);
  97     // Take historical weighted average
  98     _filter.sample(cur_plab_sz);
  99     // Clip from above and below, and align to object boundary
 100     size_t plab_sz;
 101     plab_sz = MAX2(min_size(), (size_t)_filter.average());
 102     plab_sz = MIN2(max_size(), plab_sz);
 103     plab_sz = align_object_size(plab_sz);
 104     // Latch the result
 105     _desired_net_plab_sz = plab_sz;
 106     if (PrintPLAB) {
 107       gclog_or_tty->print(" (plab_sz = " SIZE_FORMAT " desired_plab_sz = " SIZE_FORMAT ") ", cur_plab_sz, plab_sz);
 108     }
 109   }
 110   if (PrintPLAB) {
 111     gclog_or_tty->cr();
 112   }




 113   // Clear accumulators for next round.
 114   reset();
 115 }
 116 


   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 #include "precompiled.hpp"
  26 #include "gc/g1/g1EvacStats.hpp"
  27 #include "gc/shared/gcId.hpp"
  28 #include "logging/log.hpp"
  29 #include "trace/tracing.hpp"
  30 
  31 void G1EvacStats::adjust_desired_plab_sz() {
  32   if (!ResizePLAB) {
  33     log_debug(gc, plab)(" (allocated = " SIZE_FORMAT " wasted = " SIZE_FORMAT " "
  34                         "unused = " SIZE_FORMAT " used = " SIZE_FORMAT " "
  35                         "undo_waste = " SIZE_FORMAT " region_end_waste = " SIZE_FORMAT " "
  36                         "regions filled = %u direct_allocated = " SIZE_FORMAT " "
  37                         "failure_used = " SIZE_FORMAT " failure_waste = " SIZE_FORMAT ") ",
  38                         _allocated, _wasted, _unused, used(), _undo_wasted, _region_end_waste,
  39                         _regions_filled, _direct_allocated, _failure_used, _failure_waste);
  40     // Clear accumulators for next round.
  41     reset();
  42     return;
  43   }
  44 


  45   assert(is_object_aligned(max_size()) && min_size() <= max_size(),
  46          "PLAB clipping computation may be incorrect");
  47 
  48   if (_allocated == 0) {
  49     assert((_unused == 0),
  50            "Inconsistency in PLAB stats: "
  51            "_allocated: " SIZE_FORMAT ", "
  52            "_wasted: " SIZE_FORMAT ", "
  53            "_region_end_waste: " SIZE_FORMAT ", "
  54            "_unused: " SIZE_FORMAT ", "
  55            "_used  : " SIZE_FORMAT,
  56            _allocated, _wasted, _region_end_waste, _unused, used());
  57     _allocated = 1;
  58   }
  59   // The size of the PLAB caps the amount of space that can be wasted at the
  60   // end of the collection. In the worst case the last PLAB could be completely
  61   // empty.
  62   // This allows us to calculate the new PLAB size to achieve the
  63   // TargetPLABWastePct given the latest memory usage and that the last buffer
  64   // will be G1LastPLABAverageOccupancy full.


  88   //
  89   // We need to cover overflow when calculating the amount of space actually used
  90   // by objects in PLABs when subtracting the region end waste.
  91   // Region end waste may be higher than actual allocation. This may occur if many
  92   // threads do not allocate anything but a few rather large objects. In this
  93   // degenerate case the PLAB size would simply quickly tend to minimum PLAB size,
  94   // which is an okay reaction.
  95   size_t const used_for_waste_calculation = used() > _region_end_waste ? used() - _region_end_waste : 0;
  96 
  97   size_t const total_waste_allowed = used_for_waste_calculation * TargetPLABWastePct;
  98   size_t const cur_plab_sz = (size_t)((double)total_waste_allowed / G1LastPLABAverageOccupancy);
  99   // Take historical weighted average
 100   _filter.sample(cur_plab_sz);
 101   // Clip from above and below, and align to object boundary
 102   size_t plab_sz;
 103   plab_sz = MAX2(min_size(), (size_t)_filter.average());
 104   plab_sz = MIN2(max_size(), plab_sz);
 105   plab_sz = align_object_size(plab_sz);
 106   // Latch the result
 107   _desired_net_plab_sz = plab_sz;
 108 
 109   log_debug(gc, plab)(" (allocated = " SIZE_FORMAT " wasted = " SIZE_FORMAT " "
 110                       "unused = " SIZE_FORMAT " used = " SIZE_FORMAT " "
 111                       "undo_waste = " SIZE_FORMAT " region_end_waste = " SIZE_FORMAT " "
 112                       "regions filled = %u direct_allocated = " SIZE_FORMAT " "
 113                       "failure_used = " SIZE_FORMAT " failure_waste = " SIZE_FORMAT ") "
 114                       " (plab_sz = " SIZE_FORMAT " desired_plab_sz = " SIZE_FORMAT ")",
 115                       _allocated, _wasted, _unused, used(), _undo_wasted, _region_end_waste,
 116                       _regions_filled, _direct_allocated, _failure_used, _failure_waste,
 117                       cur_plab_sz, plab_sz);
 118 
 119   // Clear accumulators for next round.
 120   reset();
 121 }
 122 
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