1 /*
   2  * Copyright (c) 2015, 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.
  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              err_msg("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     // We account region end waste fully to PLAB allocation. This is not completely fair,
  58     // but is a conservative assumption because PLABs may be sized flexibly while we
  59     // cannot adjust direct allocations.
  60     // In some cases, wasted_frac may become > 1 but that just reflects the problem
  61     // with region_end_waste.
  62     double wasted_frac    = (double)(_unused + _wasted + _region_end_waste) / (double)_allocated;
  63     size_t target_refills = (size_t)((wasted_frac * TargetSurvivorRatio) / TargetPLABWastePct);
  64     if (target_refills == 0) {
  65       target_refills = 1;
  66     }
  67     size_t cur_plab_sz = used() / target_refills;
  68     // Take historical weighted average
  69     _filter.sample(cur_plab_sz);
  70     // Clip from above and below, and align to object boundary
  71     size_t plab_sz;
  72     plab_sz = MAX2(min_size(), (size_t)_filter.average());
  73     plab_sz = MIN2(max_size(), plab_sz);
  74     plab_sz = align_object_size(plab_sz);
  75     // Latch the result
  76     _desired_net_plab_sz = plab_sz;
  77     if (PrintPLAB) {
  78       gclog_or_tty->print_cr(" (plab_sz = " SIZE_FORMAT " desired_plab_sz = " SIZE_FORMAT ") ", cur_plab_sz, plab_sz);
  79     }
  80   }
  81   // Clear accumulators for next round.
  82   reset();
  83 }
  84