--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/hotspot/src/share/vm/gc_implementation/g1/g1MMUTracker.cpp Thu Jun 05 15:57:56 2008 -0700
@@ -0,0 +1,187 @@
+/*
+ * Copyright 2001-2007 Sun Microsystems, Inc. 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
+ * CA 95054 USA or visit www.sun.com if you need additional information or
+ * have any questions.
+ *
+ */
+
+#include "incls/_precompiled.incl"
+#include "incls/_g1MMUTracker.cpp.incl"
+
+#define _DISABLE_MMU 0
+
+// can't rely on comparing doubles with tolerating a small margin for error
+#define SMALL_MARGIN 0.0000001
+#define is_double_leq_0(_value) ( (_value) < SMALL_MARGIN )
+#define is_double_leq(_val1, _val2) is_double_leq_0((_val1) - (_val2))
+#define is_double_geq(_val1, _val2) is_double_leq_0((_val2) - (_val1))
+
+/***** ALL TIMES ARE IN SECS!!!!!!! *****/
+
+G1MMUTracker::G1MMUTracker(double time_slice, double max_gc_time) :
+ _time_slice(time_slice),
+ _max_gc_time(max_gc_time),
+ _conc_overhead_time_sec(0.0) { }
+
+void
+G1MMUTracker::update_conc_overhead(double conc_overhead) {
+ double conc_overhead_time_sec = _time_slice * conc_overhead;
+ if (conc_overhead_time_sec > 0.9 * _max_gc_time) {
+ // We are screwed, as we only seem to have <10% of the soft
+ // real-time goal available for pauses. Let's admit defeat and
+ // allow something more generous as a pause target.
+ conc_overhead_time_sec = 0.75 * _max_gc_time;
+ }
+
+ _conc_overhead_time_sec = conc_overhead_time_sec;
+}
+
+G1MMUTrackerQueue::G1MMUTrackerQueue(double time_slice, double max_gc_time) :
+ G1MMUTracker(time_slice, max_gc_time),
+ _head_index(0),
+ _tail_index(trim_index(_head_index+1)),
+ _no_entries(0) { }
+
+void G1MMUTrackerQueue::remove_expired_entries(double current_time) {
+ double limit = current_time - _time_slice;
+ while (_no_entries > 0) {
+ if (is_double_geq(limit, _array[_tail_index].end_time())) {
+ _tail_index = trim_index(_tail_index + 1);
+ --_no_entries;
+ } else
+ return;
+ }
+ guarantee(_no_entries == 0, "should have no entries in the array");
+}
+
+double G1MMUTrackerQueue::calculate_gc_time(double current_time) {
+ double gc_time = 0.0;
+ double limit = current_time - _time_slice;
+ for (int i = 0; i < _no_entries; ++i) {
+ int index = trim_index(_tail_index + i);
+ G1MMUTrackerQueueElem *elem = &_array[index];
+ if (elem->end_time() > limit) {
+ if (elem->start_time() > limit)
+ gc_time += elem->duration();
+ else
+ gc_time += elem->end_time() - limit;
+ }
+ }
+ return gc_time;
+}
+
+void G1MMUTrackerQueue::add_pause(double start, double end, bool gc_thread) {
+ double longest_allowed = longest_pause_internal(start);
+ if (longest_allowed < 0.0)
+ longest_allowed = 0.0;
+ double duration = end - start;
+
+ remove_expired_entries(end);
+ if (_no_entries == QueueLength) {
+ // OK, right now when we fill up we bomb out
+ // there are a few ways of dealing with this "gracefully"
+ // increase the array size (:-)
+ // remove the oldest entry (this might allow more GC time for
+ // the time slice than what's allowed)
+ // concolidate the two entries with the minimum gap between them
+ // (this mighte allow less GC time than what's allowed)
+ guarantee(0, "array full, currently we can't recover");
+ }
+ _head_index = trim_index(_head_index + 1);
+ ++_no_entries;
+ _array[_head_index] = G1MMUTrackerQueueElem(start, end);
+}
+
+// basically the _internal call does not remove expired entries
+// this is for trying things out in the future and a couple
+// of other places (debugging)
+
+double G1MMUTrackerQueue::longest_pause(double current_time) {
+ if (_DISABLE_MMU)
+ return _max_gc_time;
+
+ MutexLockerEx x(MMUTracker_lock, Mutex::_no_safepoint_check_flag);
+ remove_expired_entries(current_time);
+
+ return longest_pause_internal(current_time);
+}
+
+double G1MMUTrackerQueue::longest_pause_internal(double current_time) {
+ double target_time = _max_gc_time;
+
+ while( 1 ) {
+ double gc_time =
+ calculate_gc_time(current_time + target_time) + _conc_overhead_time_sec;
+ double diff = target_time + gc_time - _max_gc_time;
+ if (!is_double_leq_0(diff)) {
+ target_time -= diff;
+ if (is_double_leq_0(target_time)) {
+ target_time = -1.0;
+ break;
+ }
+ } else {
+ break;
+ }
+ }
+
+ return target_time;
+}
+
+// basically the _internal call does not remove expired entries
+// this is for trying things out in the future and a couple
+// of other places (debugging)
+
+double G1MMUTrackerQueue::when_sec(double current_time, double pause_time) {
+ if (_DISABLE_MMU)
+ return 0.0;
+
+ MutexLockerEx x(MMUTracker_lock, Mutex::_no_safepoint_check_flag);
+ remove_expired_entries(current_time);
+
+ return when_internal(current_time, pause_time);
+}
+
+double G1MMUTrackerQueue::when_internal(double current_time,
+ double pause_time) {
+ // if the pause is over the maximum, just assume that it's the maximum
+ double adjusted_pause_time =
+ (pause_time > max_gc_time()) ? max_gc_time() : pause_time;
+ double earliest_end = current_time + adjusted_pause_time;
+ double limit = earliest_end - _time_slice;
+ double gc_time = calculate_gc_time(earliest_end);
+ double diff = gc_time + adjusted_pause_time - max_gc_time();
+ if (is_double_leq_0(diff))
+ return 0.0;
+
+ int index = _tail_index;
+ while ( 1 ) {
+ G1MMUTrackerQueueElem *elem = &_array[index];
+ if (elem->end_time() > limit) {
+ if (elem->start_time() > limit)
+ diff -= elem->duration();
+ else
+ diff -= elem->end_time() - limit;
+ if (is_double_leq_0(diff))
+ return elem->end_time() + diff + _time_slice - adjusted_pause_time - current_time;
+ }
+ index = trim_index(index+1);
+ guarantee(index != trim_index(_head_index + 1), "should not go past head");
+ }
+}