--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/hotspot/share/gc/g1/g1EvacStats.cpp	Tue Sep 12 19:03:39 2017 +0200
@@ -0,0 +1,103 @@
+/*
+ * Copyright (c) 2015, 2017, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ *
+ */
+
+#include "precompiled.hpp"
+#include "memory/allocation.inline.hpp"
+#include "gc/g1/g1_globals.hpp"
+#include "gc/g1/g1EvacStats.hpp"
+#include "gc/shared/gcId.hpp"
+#include "logging/log.hpp"
+#include "trace/tracing.hpp"
+
+void G1EvacStats::log_plab_allocation() {
+  PLABStats::log_plab_allocation();
+  log_debug(gc, plab)("%s other allocation: "
+                      "region end waste: " SIZE_FORMAT "B, "
+                      "regions filled: %u, "
+                      "direct allocated: " SIZE_FORMAT "B, "
+                      "failure used: " SIZE_FORMAT "B, "
+                      "failure wasted: " SIZE_FORMAT "B",
+                      _description,
+                      _region_end_waste * HeapWordSize,
+                      _regions_filled,
+                      _direct_allocated * HeapWordSize,
+                      _failure_used * HeapWordSize,
+                      _failure_waste * HeapWordSize);
+}
+
+size_t G1EvacStats::compute_desired_plab_sz() {
+  // The size of the PLAB caps the amount of space that can be wasted at the
+  // end of the collection. In the worst case the last PLAB could be completely
+  // empty.
+  // This allows us to calculate the new PLAB size to achieve the
+  // TargetPLABWastePct given the latest memory usage and that the last buffer
+  // will be G1LastPLABAverageOccupancy full.
+  //
+  // E.g. assume that if in the current GC 100 words were allocated and a
+  // TargetPLABWastePct of 10 had been set.
+  //
+  // So we could waste up to 10 words to meet that percentage. Given that we
+  // also assume that that buffer is typically half-full, the new desired PLAB
+  // size is set to 20 words.
+  //
+  // The amount of allocation performed should be independent of the number of
+  // threads, so should the maximum waste we can spend in total. So if
+  // we used n threads to allocate, each of them can spend maximum waste/n words in
+  // a first rough approximation. The number of threads only comes into play later
+  // when actually retrieving the actual desired PLAB size.
+  //
+  // After calculating this optimal PLAB size the algorithm applies the usual
+  // exponential decaying average over this value to guess the next PLAB size.
+  //
+  // We account region end waste fully to PLAB allocation (in the calculation of
+  // what we consider as "used_for_waste_calculation" below). This is not
+  // completely fair, but is a conservative assumption because PLABs may be sized
+  // flexibly while we cannot adjust inline allocations.
+  // Allocation during GC will try to minimize region end waste so this impact
+  // should be minimal.
+  //
+  // We need to cover overflow when calculating the amount of space actually used
+  // by objects in PLABs when subtracting the region end waste.
+  // Region end waste may be higher than actual allocation. This may occur if many
+  // threads do not allocate anything but a few rather large objects. In this
+  // degenerate case the PLAB size would simply quickly tend to minimum PLAB size,
+  // which is an okay reaction.
+  size_t const used_for_waste_calculation = used() > _region_end_waste ? used() - _region_end_waste : 0;
+
+  size_t const total_waste_allowed = used_for_waste_calculation * TargetPLABWastePct;
+  size_t const cur_plab_sz = (size_t)((double)total_waste_allowed / G1LastPLABAverageOccupancy);
+  return cur_plab_sz;
+}
+
+G1EvacStats::G1EvacStats(const char* description, size_t desired_plab_sz_, unsigned wt) :
+  PLABStats(description, desired_plab_sz_, wt),
+  _region_end_waste(0),
+  _regions_filled(0),
+  _direct_allocated(0),
+  _failure_used(0),
+  _failure_waste(0) {
+}
+
+
+G1EvacStats::~G1EvacStats() { }