xapian-letor/tests/harness/scalability.cc

   1 /** @file scalability.cc
   2  * @brief Test how an operation scales.
   3  */
   4 /* Copyright (C) 2009 Olly Betts
   5  *
   6  * This program is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU General Public License as
   8  * published by the Free Software Foundation; either version 2 of the
   9  * License, or (at your option) any later version.
  10  *
  11  * This program is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  * GNU General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU General Public License
  17  * along with this program; if not, write to the Free Software
  18  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301 USA
  19  */
  20
  21 #include <config.h>
  22
  23 #include "scalability.h"
  24
  25 #include "cputimer.h"
  26 #include "testsuite.h"
  27
  28 void
  29 test_scalability(double (*func)(unsigned), unsigned n, double threshold)
  30 {
  31     double time1;
  32     // Increase the number of tests until we take a reliably measurable amount
  33     // of time.
  34     do {
  35         time1 = func(n);
  36         tout << "Test with " << n << " repetitions took " << time1 << " secs\n";
  37         unsigned n_new = n * 10;
  38         if (n_new < n)
  39             SKIP_TEST("Can't count enough repetitions to be able to time test");
  40         n = n_new;
  41     } while (time1 <= 0.001);
  42
  43     double time10 = func(n);
  44     tout << "Test with " << n << " repetitions took " << time10 << " secs\n";
  45
  46     TEST_REL(time10,<,time1 * threshold);
  47 }