--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/share/vm/gc_implementation/shared/adaptiveSizePolicy.cpp	Sat Dec 01 00:00:00 2007 +0000
@@ -0,0 +1,392 @@
+/*
+ * Copyright 2004-2006 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/_adaptiveSizePolicy.cpp.incl"
+
+elapsedTimer AdaptiveSizePolicy::_minor_timer;
+elapsedTimer AdaptiveSizePolicy::_major_timer;
+
+// The throughput goal is implemented as
+//      _throughput_goal = 1 - ( 1 / (1 + gc_cost_ratio))
+// gc_cost_ratio is the ratio
+//      application cost / gc cost
+// For example a gc_cost_ratio of 4 translates into a
+// throughput goal of .80
+
+AdaptiveSizePolicy::AdaptiveSizePolicy(size_t init_eden_size,
+                                       size_t init_promo_size,
+                                       size_t init_survivor_size,
+                                       double gc_pause_goal_sec,
+                                       uint gc_cost_ratio) :
+    _eden_size(init_eden_size),
+    _promo_size(init_promo_size),
+    _survivor_size(init_survivor_size),
+    _gc_pause_goal_sec(gc_pause_goal_sec),
+    _throughput_goal(1.0 - double(1.0 / (1.0 + (double) gc_cost_ratio))),
+    _gc_time_limit_exceeded(false),
+    _print_gc_time_limit_would_be_exceeded(false),
+    _gc_time_limit_count(0),
+    _latest_minor_mutator_interval_seconds(0),
+    _threshold_tolerance_percent(1.0 + ThresholdTolerance/100.0),
+    _young_gen_change_for_minor_throughput(0),
+    _old_gen_change_for_major_throughput(0) {
+  _avg_minor_pause    =
+    new AdaptivePaddedAverage(AdaptiveTimeWeight, PausePadding);
+  _avg_minor_interval = new AdaptiveWeightedAverage(AdaptiveTimeWeight);
+  _avg_minor_gc_cost  = new AdaptiveWeightedAverage(AdaptiveTimeWeight);
+  _avg_major_gc_cost  = new AdaptiveWeightedAverage(AdaptiveTimeWeight);
+
+  _avg_young_live     = new AdaptiveWeightedAverage(AdaptiveSizePolicyWeight);
+  _avg_old_live       = new AdaptiveWeightedAverage(AdaptiveSizePolicyWeight);
+  _avg_eden_live      = new AdaptiveWeightedAverage(AdaptiveSizePolicyWeight);
+
+  _avg_survived       = new AdaptivePaddedAverage(AdaptiveSizePolicyWeight,
+                                                  SurvivorPadding);
+  _avg_pretenured     = new AdaptivePaddedNoZeroDevAverage(
+                                                  AdaptiveSizePolicyWeight,
+                                                  SurvivorPadding);
+
+  _minor_pause_old_estimator =
+    new LinearLeastSquareFit(AdaptiveSizePolicyWeight);
+  _minor_pause_young_estimator =
+    new LinearLeastSquareFit(AdaptiveSizePolicyWeight);
+  _minor_collection_estimator =
+    new LinearLeastSquareFit(AdaptiveSizePolicyWeight);
+  _major_collection_estimator =
+    new LinearLeastSquareFit(AdaptiveSizePolicyWeight);
+
+  // Start the timers
+  _minor_timer.start();
+
+  _young_gen_policy_is_ready = false;
+}
+
+bool AdaptiveSizePolicy::tenuring_threshold_change() const {
+  return decrement_tenuring_threshold_for_gc_cost() ||
+         increment_tenuring_threshold_for_gc_cost() ||
+         decrement_tenuring_threshold_for_survivor_limit();
+}
+
+void AdaptiveSizePolicy::minor_collection_begin() {
+  // Update the interval time
+  _minor_timer.stop();
+  // Save most recent collection time
+  _latest_minor_mutator_interval_seconds = _minor_timer.seconds();
+  _minor_timer.reset();
+  _minor_timer.start();
+}
+
+void AdaptiveSizePolicy::update_minor_pause_young_estimator(
+    double minor_pause_in_ms) {
+  double eden_size_in_mbytes = ((double)_eden_size)/((double)M);
+  _minor_pause_young_estimator->update(eden_size_in_mbytes,
+    minor_pause_in_ms);
+}
+
+void AdaptiveSizePolicy::minor_collection_end(GCCause::Cause gc_cause) {
+  // Update the pause time.
+  _minor_timer.stop();
+
+  if (gc_cause != GCCause::_java_lang_system_gc ||
+      UseAdaptiveSizePolicyWithSystemGC) {
+    double minor_pause_in_seconds = _minor_timer.seconds();
+    double minor_pause_in_ms = minor_pause_in_seconds * MILLIUNITS;
+
+    // Sample for performance counter
+    _avg_minor_pause->sample(minor_pause_in_seconds);
+
+    // Cost of collection (unit-less)
+    double collection_cost = 0.0;
+    if ((_latest_minor_mutator_interval_seconds > 0.0) &&
+        (minor_pause_in_seconds > 0.0)) {
+      double interval_in_seconds =
+        _latest_minor_mutator_interval_seconds + minor_pause_in_seconds;
+      collection_cost =
+        minor_pause_in_seconds / interval_in_seconds;
+      _avg_minor_gc_cost->sample(collection_cost);
+      // Sample for performance counter
+      _avg_minor_interval->sample(interval_in_seconds);
+    }
+
+    // The policy does not have enough data until at least some
+    // minor collections have been done.
+    _young_gen_policy_is_ready =
+      (_avg_minor_gc_cost->count() >= AdaptiveSizePolicyReadyThreshold);
+
+    // Calculate variables used to estimate pause time vs. gen sizes
+    double eden_size_in_mbytes = ((double)_eden_size)/((double)M);
+    update_minor_pause_young_estimator(minor_pause_in_ms);
+    update_minor_pause_old_estimator(minor_pause_in_ms);
+
+    if (PrintAdaptiveSizePolicy && Verbose) {
+      gclog_or_tty->print("AdaptiveSizePolicy::minor_collection_end: "
+        "minor gc cost: %f  average: %f", collection_cost,
+        _avg_minor_gc_cost->average());
+      gclog_or_tty->print_cr("  minor pause: %f minor period %f",
+        minor_pause_in_ms,
+        _latest_minor_mutator_interval_seconds * MILLIUNITS);
+    }
+
+    // Calculate variable used to estimate collection cost vs. gen sizes
+    assert(collection_cost >= 0.0, "Expected to be non-negative");
+    _minor_collection_estimator->update(eden_size_in_mbytes, collection_cost);
+  }
+
+  // Interval times use this timer to measure the mutator time.
+  // Reset the timer after the GC pause.
+  _minor_timer.reset();
+  _minor_timer.start();
+}
+
+size_t AdaptiveSizePolicy::eden_increment(size_t cur_eden,
+                                            uint percent_change) {
+  size_t eden_heap_delta;
+  eden_heap_delta = cur_eden / 100 * percent_change;
+  return eden_heap_delta;
+}
+
+size_t AdaptiveSizePolicy::eden_increment(size_t cur_eden) {
+  return eden_increment(cur_eden, YoungGenerationSizeIncrement);
+}
+
+size_t AdaptiveSizePolicy::eden_decrement(size_t cur_eden) {
+  size_t eden_heap_delta = eden_increment(cur_eden) /
+    AdaptiveSizeDecrementScaleFactor;
+  return eden_heap_delta;
+}
+
+size_t AdaptiveSizePolicy::promo_increment(size_t cur_promo,
+                                             uint percent_change) {
+  size_t promo_heap_delta;
+  promo_heap_delta = cur_promo / 100 * percent_change;
+  return promo_heap_delta;
+}
+
+size_t AdaptiveSizePolicy::promo_increment(size_t cur_promo) {
+  return promo_increment(cur_promo, TenuredGenerationSizeIncrement);
+}
+
+size_t AdaptiveSizePolicy::promo_decrement(size_t cur_promo) {
+  size_t promo_heap_delta = promo_increment(cur_promo);
+  promo_heap_delta = promo_heap_delta / AdaptiveSizeDecrementScaleFactor;
+  return promo_heap_delta;
+}
+
+double AdaptiveSizePolicy::time_since_major_gc() const {
+  _major_timer.stop();
+  double result = _major_timer.seconds();
+  _major_timer.start();
+  return result;
+}
+
+// Linear decay of major gc cost
+double AdaptiveSizePolicy::decaying_major_gc_cost() const {
+  double major_interval = major_gc_interval_average_for_decay();
+  double major_gc_cost_average = major_gc_cost();
+  double decayed_major_gc_cost = major_gc_cost_average;
+  if(time_since_major_gc() > 0.0) {
+    decayed_major_gc_cost = major_gc_cost() *
+      (((double) AdaptiveSizeMajorGCDecayTimeScale) * major_interval)
+      / time_since_major_gc();
+  }
+
+  // The decayed cost should always be smaller than the
+  // average cost but the vagaries of finite arithmetic could
+  // produce a larger value in decayed_major_gc_cost so protect
+  // against that.
+  return MIN2(major_gc_cost_average, decayed_major_gc_cost);
+}
+
+// Use a value of the major gc cost that has been decayed
+// by the factor
+//
+//      average-interval-between-major-gc * AdaptiveSizeMajorGCDecayTimeScale /
+//        time-since-last-major-gc
+//
+// if the average-interval-between-major-gc * AdaptiveSizeMajorGCDecayTimeScale
+// is less than time-since-last-major-gc.
+//
+// In cases where there are initial major gc's that
+// are of a relatively high cost but no later major
+// gc's, the total gc cost can remain high because
+// the major gc cost remains unchanged (since there are no major
+// gc's).  In such a situation the value of the unchanging
+// major gc cost can keep the mutator throughput below
+// the goal when in fact the major gc cost is becoming diminishingly
+// small.  Use the decaying gc cost only to decide whether to
+// adjust for throughput.  Using it also to determine the adjustment
+// to be made for throughput also seems reasonable but there is
+// no test case to use to decide if it is the right thing to do
+// don't do it yet.
+
+double AdaptiveSizePolicy::decaying_gc_cost() const {
+  double decayed_major_gc_cost = major_gc_cost();
+  double avg_major_interval = major_gc_interval_average_for_decay();
+  if (UseAdaptiveSizeDecayMajorGCCost &&
+      (AdaptiveSizeMajorGCDecayTimeScale > 0) &&
+      (avg_major_interval > 0.00)) {
+    double time_since_last_major_gc = time_since_major_gc();
+
+    // Decay the major gc cost?
+    if (time_since_last_major_gc >
+        ((double) AdaptiveSizeMajorGCDecayTimeScale) * avg_major_interval) {
+
+      // Decay using the time-since-last-major-gc
+      decayed_major_gc_cost = decaying_major_gc_cost();
+      if (PrintGCDetails && Verbose) {
+        gclog_or_tty->print_cr("\ndecaying_gc_cost: major interval average:"
+          " %f  time since last major gc: %f",
+          avg_major_interval, time_since_last_major_gc);
+        gclog_or_tty->print_cr("  major gc cost: %f  decayed major gc cost: %f",
+          major_gc_cost(), decayed_major_gc_cost);
+      }
+    }
+  }
+  double result = MIN2(1.0, decayed_major_gc_cost + minor_gc_cost());
+  return result;
+}
+
+
+void AdaptiveSizePolicy::clear_generation_free_space_flags() {
+  set_change_young_gen_for_min_pauses(0);
+  set_change_old_gen_for_maj_pauses(0);
+
+  set_change_old_gen_for_throughput(0);
+  set_change_young_gen_for_throughput(0);
+  set_decrease_for_footprint(0);
+  set_decide_at_full_gc(0);
+}
+
+// Printing
+
+bool AdaptiveSizePolicy::print_adaptive_size_policy_on(outputStream* st) const {
+
+  //  Should only be used with adaptive size policy turned on.
+  // Otherwise, there may be variables that are undefined.
+  if (!UseAdaptiveSizePolicy) return false;
+
+  // Print goal for which action is needed.
+  char* action = NULL;
+  bool change_for_pause = false;
+  if ((change_old_gen_for_maj_pauses() ==
+         decrease_old_gen_for_maj_pauses_true) ||
+      (change_young_gen_for_min_pauses() ==
+         decrease_young_gen_for_min_pauses_true)) {
+    action = (char*) " *** pause time goal ***";
+    change_for_pause = true;
+  } else if ((change_old_gen_for_throughput() ==
+               increase_old_gen_for_throughput_true) ||
+            (change_young_gen_for_throughput() ==
+               increase_young_gen_for_througput_true)) {
+    action = (char*) " *** throughput goal ***";
+  } else if (decrease_for_footprint()) {
+    action = (char*) " *** reduced footprint ***";
+  } else {
+    // No actions were taken.  This can legitimately be the
+    // situation if not enough data has been gathered to make
+    // decisions.
+    return false;
+  }
+
+  // Pauses
+  // Currently the size of the old gen is only adjusted to
+  // change the major pause times.
+  char* young_gen_action = NULL;
+  char* tenured_gen_action = NULL;
+
+  char* shrink_msg = (char*) "(attempted to shrink)";
+  char* grow_msg = (char*) "(attempted to grow)";
+  char* no_change_msg = (char*) "(no change)";
+  if (change_young_gen_for_min_pauses() ==
+      decrease_young_gen_for_min_pauses_true) {
+    young_gen_action = shrink_msg;
+  } else if (change_for_pause) {
+    young_gen_action = no_change_msg;
+  }
+
+  if (change_old_gen_for_maj_pauses() == decrease_old_gen_for_maj_pauses_true) {
+    tenured_gen_action = shrink_msg;
+  } else if (change_for_pause) {
+    tenured_gen_action = no_change_msg;
+  }
+
+  // Throughput
+  if (change_old_gen_for_throughput() == increase_old_gen_for_throughput_true) {
+    assert(change_young_gen_for_throughput() ==
+           increase_young_gen_for_througput_true,
+           "Both generations should be growing");
+    young_gen_action = grow_msg;
+    tenured_gen_action = grow_msg;
+  } else if (change_young_gen_for_throughput() ==
+             increase_young_gen_for_througput_true) {
+    // Only the young generation may grow at start up (before
+    // enough full collections have been done to grow the old generation).
+    young_gen_action = grow_msg;
+    tenured_gen_action = no_change_msg;
+  }
+
+  // Minimum footprint
+  if (decrease_for_footprint() != 0) {
+    young_gen_action = shrink_msg;
+    tenured_gen_action = shrink_msg;
+  }
+
+  st->print_cr("    UseAdaptiveSizePolicy actions to meet %s", action);
+  st->print_cr("                       GC overhead (%%)");
+  st->print_cr("    Young generation:     %7.2f\t  %s",
+    100.0 * avg_minor_gc_cost()->average(),
+    young_gen_action);
+  st->print_cr("    Tenured generation:   %7.2f\t  %s",
+    100.0 * avg_major_gc_cost()->average(),
+    tenured_gen_action);
+  return true;
+}
+
+bool AdaptiveSizePolicy::print_adaptive_size_policy_on(
+                                            outputStream* st,
+                                            int tenuring_threshold_arg) const {
+  if (!AdaptiveSizePolicy::print_adaptive_size_policy_on(st)) {
+    return false;
+  }
+
+  // Tenuring threshold
+  bool tenuring_threshold_changed = true;
+  if (decrement_tenuring_threshold_for_survivor_limit()) {
+    st->print("    Tenuring threshold:    (attempted to decrease to avoid"
+              " survivor space overflow) = ");
+  } else if (decrement_tenuring_threshold_for_gc_cost()) {
+    st->print("    Tenuring threshold:    (attempted to decrease to balance"
+              " GC costs) = ");
+  } else if (increment_tenuring_threshold_for_gc_cost()) {
+    st->print("    Tenuring threshold:    (attempted to increase to balance"
+              " GC costs) = ");
+  } else {
+    tenuring_threshold_changed = false;
+    assert(!tenuring_threshold_change(), "(no change was attempted)");
+  }
+  if (tenuring_threshold_changed) {
+    st->print_cr("%d", tenuring_threshold_arg);
+  }
+  return true;
+}