src/Tuner/autotuner.cc

   1 #include "autotuner.h"
   2 #include "csolver.h"
   3 #include "searchtuner.h"
   4 #include <math.h>
   5 #include <stdlib.h>
   6 #include <float.h>
   7
   8 AutoTuner::AutoTuner(uint _budget) :
   9         budget(_budget) {
  10 }
  11
  12 void AutoTuner::addProblem(CSolver *solver) {
  13         solvers.push(solver);
  14 }
  15
  16 long long AutoTuner::evaluate(CSolver * problem, SearchTuner *tuner) {
  17         CSolver * copy=problem->clone();
  18         copy->setTuner(tuner);
  19         int result = copy->startEncoding();
  20         long long elapsedTime=copy->getElapsedTime();
  21         long long encodeTime=copy->getEncodeTime();
  22         long long solveTime=copy->getSolveTime();
  23         long long metric=elapsedTime;
  24         delete copy;
  25         return metric;
  26 }
  27
  28 double AutoTuner::evaluateAll(SearchTuner *tuner) {
  29         double product=1;
  30         for(uint i=0;i<solvers.getSize();i++) {
  31                 CSolver * problem=solvers.get(i);
  32                 double score=evaluate(problem, tuner);
  33                 product*=score;
  34         }
  35         return pow(product, 1/((double)solvers.getSize()));
  36 }
  37
  38 SearchTuner * AutoTuner::mutateTuner(SearchTuner * oldTuner, uint k) {
  39         SearchTuner *newTuner=oldTuner->copyUsed();
  40         uint numSettings=oldTuner->getSize();
  41         double factor=0.3;//Adjust this factor...
  42         uint settingsToMutate=(uint)(factor*(((double)numSettings) * k)/(budget));
  43         if (settingsToMutate < 1)
  44                 settingsToMutate=1;
  45         model_print("Mutating %u settings\n", settingsToMutate);
  46         while(settingsToMutate-- != 0) {
  47                 newTuner->randomMutate();
  48         }
  49         return newTuner;
  50 }
  51
  52
  53 void AutoTuner::tune() {
  54         SearchTuner * bestTuner = NULL;
  55         double bestScore=DBL_MAX;
  56
  57         SearchTuner * oldTuner=new SearchTuner();
  58         double base_temperature=evaluateAll(oldTuner);
  59         double oldScore=base_temperature;
  60
  61         for (uint i=0;i<budget;i++) {
  62                 SearchTuner *newTuner=mutateTuner(oldTuner, i);
  63                 double newScore=evaluateAll(newTuner);
  64                 double scoreDiff=newScore - oldScore; //smaller is better
  65                 if (newScore < bestScore) {
  66                         bestScore = newScore;
  67                         bestTuner = newTuner->copyUsed();
  68                 }
  69
  70                 double acceptanceP;
  71                 if (scoreDiff < 0) {
  72                         acceptanceP = 1;
  73                 } else {
  74                         double currTemp=base_temperature * (((double)budget - i) / budget);
  75                         acceptanceP = exp(-scoreDiff / currTemp);
  76                 }
  77                 double ran = ((double)random()) / RAND_MAX;
  78                 if (ran <= acceptanceP) {
  79                         oldScore = newScore;
  80                         oldTuner = newTuner;
  81                 } else {
  82                         delete newTuner;
  83                 }
  84         }
  85 }