exp-test.cc
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// probe/exp-test.cc
// Copyright 2014 Yandex LLC (Author: Ilya Edrenkin)
// See ../../COPYING for clarification regarding multiple authors
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// THIS CODE IS PROVIDED *AS IS* BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
// KIND, EITHER EXPRESS OR IMPLIED, INCLUDING WITHOUT LIMITATION ANY IMPLIED
// WARRANTIES OR CONDITIONS OF TITLE, FITNESS FOR A PARTICULAR PURPOSE,
// MERCHANTABLITY OR NON-INFRINGEMENT.
// See the Apache 2 License for the specific language governing permissions and
// limitations under the License.
// Read Makefile.slow_expf. This test must be compiled with -O0.
#include <iostream>
#include <cmath>
#include "base/timer.h"
int main() {
int test_iter = 300000;
// Make sure that the CPU bumps its clock to full speed: run the first loop
// without timing. Then increase the sample iteration count exponentially
// until the loop takes at least 10ms. We run this loop 1/4 of the number of
// actual test iterations and call both exp() and expf(), so that the overall
// test run will take 20 to 60 ms, to ensure a sensibly measurable result.
for (bool first = true; ; first=false) {
kaldi::Timer timer;
for(int i = 0; i < test_iter; i += 4) {
(void)exp((double)(i & 0x0F));
(void)expf((double)(i & 0x0F));
}
double time = timer.Elapsed();
if (first) continue;
if (time > 0.01) break;
test_iter *= 3;
}
kaldi::Timer exp_timer;
for(int i = 0; i < test_iter; ++i) {
(void)exp((double)(i & 0x0F));
}
double exp_time = exp_timer.Elapsed();
kaldi::Timer expf_timer;
for(int i = 0; i < test_iter; ++i) {
(void)expf((double)(i & 0x0F));
}
double expf_time = expf_timer.Elapsed();
double ratio = expf_time / exp_time;
if (ratio < 1.1) {
// Often exp() and expf() perform very similarly, so we will replace expf()
// by exp() only if there is at least 10% difference.
return 0;
}
std::cerr << ("WARNING: slow expf() detected. expf() is slower than exp() "
"by the factor of ") << ratio << "\n";
return 1;
}