--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/src/hotspot/share/gc/shared/plab.cpp Tue Sep 12 19:03:39 2017 +0200
@@ -0,0 +1,186 @@
+/*
+ * Copyright (c) 2001, 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 "gc/shared/collectedHeap.hpp"
+#include "gc/shared/plab.inline.hpp"
+#include "gc/shared/threadLocalAllocBuffer.hpp"
+#include "logging/log.hpp"
+#include "oops/arrayOop.hpp"
+#include "oops/oop.inline.hpp"
+
+size_t PLAB::min_size() {
+ // Make sure that we return something that is larger than AlignmentReserve
+ return align_object_size(MAX2(MinTLABSize / HeapWordSize, (uintx)oopDesc::header_size())) + AlignmentReserve;
+}
+
+size_t PLAB::max_size() {
+ return ThreadLocalAllocBuffer::max_size();
+}
+
+PLAB::PLAB(size_t desired_plab_sz_) :
+ _word_sz(desired_plab_sz_), _bottom(NULL), _top(NULL),
+ _end(NULL), _hard_end(NULL), _allocated(0), _wasted(0), _undo_wasted(0)
+{
+ // ArrayOopDesc::header_size depends on command line initialization.
+ AlignmentReserve = oopDesc::header_size() > MinObjAlignment ? align_object_size(arrayOopDesc::header_size(T_INT)) : 0;
+ assert(min_size() > AlignmentReserve,
+ "Minimum PLAB size " SIZE_FORMAT " must be larger than alignment reserve " SIZE_FORMAT " "
+ "to be able to contain objects", min_size(), AlignmentReserve);
+}
+
+// If the minimum object size is greater than MinObjAlignment, we can
+// end up with a shard at the end of the buffer that's smaller than
+// the smallest object. We can't allow that because the buffer must
+// look like it's full of objects when we retire it, so we make
+// sure we have enough space for a filler int array object.
+size_t PLAB::AlignmentReserve;
+
+void PLAB::flush_and_retire_stats(PLABStats* stats) {
+ // Retire the last allocation buffer.
+ size_t unused = retire_internal();
+
+ // Now flush the statistics.
+ stats->add_allocated(_allocated);
+ stats->add_wasted(_wasted);
+ stats->add_undo_wasted(_undo_wasted);
+ stats->add_unused(unused);
+
+ // Since we have flushed the stats we need to clear the _allocated and _wasted
+ // fields in case somebody retains an instance of this over GCs. Not doing so
+ // will artifically inflate the values in the statistics.
+ _allocated = 0;
+ _wasted = 0;
+ _undo_wasted = 0;
+}
+
+void PLAB::retire() {
+ _wasted += retire_internal();
+}
+
+size_t PLAB::retire_internal() {
+ size_t result = 0;
+ if (_top < _hard_end) {
+ CollectedHeap::fill_with_object(_top, _hard_end);
+ result += invalidate();
+ }
+ return result;
+}
+
+void PLAB::add_undo_waste(HeapWord* obj, size_t word_sz) {
+ CollectedHeap::fill_with_object(obj, word_sz);
+ _undo_wasted += word_sz;
+}
+
+void PLAB::undo_last_allocation(HeapWord* obj, size_t word_sz) {
+ assert(pointer_delta(_top, _bottom) >= word_sz, "Bad undo");
+ assert(pointer_delta(_top, obj) == word_sz, "Bad undo");
+ _top = obj;
+}
+
+void PLAB::undo_allocation(HeapWord* obj, size_t word_sz) {
+ // Is the alloc in the current alloc buffer?
+ if (contains(obj)) {
+ assert(contains(obj + word_sz - 1),
+ "should contain whole object");
+ undo_last_allocation(obj, word_sz);
+ } else {
+ add_undo_waste(obj, word_sz);
+ }
+}
+
+void PLABStats::log_plab_allocation() {
+ log_debug(gc, plab)("%s PLAB allocation: "
+ "allocated: " SIZE_FORMAT "B, "
+ "wasted: " SIZE_FORMAT "B, "
+ "unused: " SIZE_FORMAT "B, "
+ "used: " SIZE_FORMAT "B, "
+ "undo waste: " SIZE_FORMAT "B, ",
+ _description,
+ _allocated * HeapWordSize,
+ _wasted * HeapWordSize,
+ _unused * HeapWordSize,
+ used() * HeapWordSize,
+ _undo_wasted * HeapWordSize);
+}
+
+void PLABStats::log_sizing(size_t calculated_words, size_t net_desired_words) {
+ log_debug(gc, plab)("%s sizing: "
+ "calculated: " SIZE_FORMAT "B, "
+ "actual: " SIZE_FORMAT "B",
+ _description,
+ calculated_words * HeapWordSize,
+ net_desired_words * HeapWordSize);
+}
+
+// Calculates plab size for current number of gc worker threads.
+size_t PLABStats::desired_plab_sz(uint no_of_gc_workers) {
+ return align_object_size(MIN2(MAX2(min_size(), _desired_net_plab_sz / no_of_gc_workers), max_size()));
+}
+
+// Compute desired plab size for one gc worker thread and latch result for later
+// use. This should be called once at the end of parallel
+// scavenge; it clears the sensor accumulators.
+void PLABStats::adjust_desired_plab_sz() {
+ log_plab_allocation();
+
+ if (!ResizePLAB) {
+ // Clear accumulators for next round.
+ reset();
+ return;
+ }
+
+ assert(is_object_aligned(max_size()) && min_size() <= max_size(),
+ "PLAB clipping computation may be incorrect");
+
+ assert(_allocated != 0 || _unused == 0,
+ "Inconsistency in PLAB stats: "
+ "_allocated: " SIZE_FORMAT ", "
+ "_wasted: " SIZE_FORMAT ", "
+ "_unused: " SIZE_FORMAT ", "
+ "_undo_wasted: " SIZE_FORMAT,
+ _allocated, _wasted, _unused, _undo_wasted);
+
+ size_t plab_sz = compute_desired_plab_sz();
+ // Take historical weighted average
+ _filter.sample(plab_sz);
+ _desired_net_plab_sz = MAX2(min_size(), (size_t)_filter.average());
+
+ log_sizing(plab_sz, _desired_net_plab_sz);
+ // Clear accumulators for next round
+ reset();
+}
+
+size_t PLABStats::compute_desired_plab_sz() {
+ size_t allocated = MAX2(_allocated, size_t(1));
+ double wasted_frac = (double)_unused / (double)allocated;
+ size_t target_refills = (size_t)((wasted_frac * TargetSurvivorRatio) / TargetPLABWastePct);
+ if (target_refills == 0) {
+ target_refills = 1;
+ }
+ size_t used = allocated - _wasted - _unused;
+ // Assumed to have 1 gc worker thread
+ size_t recent_plab_sz = used / target_refills;
+ return recent_plab_sz;
+}