1 /*
   2  * Copyright (c) 2016, 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 #include "precompiled.hpp"
  25 #include "gc/g1/g1Predictions.hpp"
  26 #include "unittest.hpp"
  27 
  28 static const double epsilon = 1e-6;
  29 
  30 // Some basic formula tests with confidence = 0.0
  31 TEST_VM(G1Predictions, basic_predictions) {
  32   G1Predictions predictor(0.0);
  33   TruncatedSeq s;
  34 
  35   double p0 = predictor.get_new_prediction(&s);
  36   ASSERT_LT(p0, epsilon) << "Initial prediction of empty sequence must be 0.0";
  37 
  38   s.add(5.0);
  39   double p1 = predictor.get_new_prediction(&s);
  40   ASSERT_NEAR(p1, 5.0, epsilon);
  41 
  42   for (int i = 0; i < 40; i++) {
  43     s.add(5.0);
  44   }
  45   double p2 = predictor.get_new_prediction(&s);
  46   ASSERT_NEAR(p2, 5.0, epsilon);
  47 }
  48 
  49 // The following tests checks that the initial predictions are based on
  50 // the average of the sequence and not on the stddev (which is 0).
  51 TEST_VM(G1Predictions, average_not_stdev_predictions) {
  52   G1Predictions predictor(0.5);
  53   TruncatedSeq s;
  54 
  55   s.add(1.0);
  56   double p1 = predictor.get_new_prediction(&s);
  57   ASSERT_GT(p1, s.davg()) << "First prediction must be larger than average";
  58 
  59   s.add(1.0);
  60   double p2 = predictor.get_new_prediction(&s);
  61   ASSERT_GT(p1, p2) << "First prediction must be larger than second";
  62 
  63   s.add(1.0);
  64   double p3 = predictor.get_new_prediction(&s);
  65   ASSERT_GT(p2, p3) << "Second prediction must be larger than third";
  66 
  67   s.add(1.0);
  68   s.add(1.0); // Five elements are now in the sequence.
  69   double p4 = predictor.get_new_prediction(&s);
  70   ASSERT_LT(p4, p3) << "Fourth prediction must be smaller than third";
  71   ASSERT_NEAR(p4, 1.0, epsilon);
  72 }
  73 
  74 // The following tests checks that initially prediction based on
  75 // the average is used, that gets overridden by the stddev prediction at
  76 // the end.
  77 TEST_VM(G1Predictions, average_stdev_predictions) {
  78   G1Predictions predictor(0.5);
  79   TruncatedSeq s;
  80 
  81   s.add(0.5);
  82   double p1 = predictor.get_new_prediction(&s);
  83   ASSERT_GT(p1, s.davg()) << "First prediction must be larger than average";
  84 
  85   s.add(0.2);
  86   double p2 = predictor.get_new_prediction(&s);
  87   ASSERT_GT(p1, p2) << "First prediction must be larger than second";
  88 
  89   s.add(0.5);
  90   double p3 = predictor.get_new_prediction(&s);
  91   ASSERT_GT(p2, p3) << "Second prediction must be larger than third";
  92 
  93   s.add(0.2);
  94   s.add(2.0);
  95   double p4 = predictor.get_new_prediction(&s);
  96   ASSERT_GT(p4, p3) << "Fourth prediction must be larger than third";
  97 }