sparsehist.C File Reference

Detailed Description

Evaluate the performance of THnSparse vs TH1/2/3/nF for different numbers of dimensions and bins per dimension.

The script calculates the bandwidth for filling and retrieving bin contents (in million entries per second) for these two histogramming techniques, where "seconds" is CPU and real time.

The first line of the plots contains the bandwidth based on the CPU time (THnSpase, TH1/2/3/nF*, ratio), the second line shows the plots for real time, and the third line shows the fraction of filled bins and memory used by THnSparse vs. TH1/2/3/nF.

The timing depends on the distribution and the amount of entries in the histograms; here, a Gaussian distribution (center is contained in the histograms) is used to fill each histogram with 1000 entries. The filling and reading is repeated until enough statistics have been collected.

tutorials/tree/drawsparse.C shows an example for visualizing a THnSparse. It creates a TTree which is then drawn using TParallelCoord.

This macro should be run in compiled mode due to the many nested loops that force CLING to disable its optimization. If run interpreted one would not benchmark THnSparse but CLING.

Run as:

root[0] .L $ROOTSYS/tutorials/hist/sparsehist.C+
root[1] sparsehist()

 
#include "TH1.h"
#include "TH2.h"
#include "TH3.h"
#include "THn.h"
#include "THnSparse.h"
#include "TStopwatch.h"
#include "TRandom.h"
#include "TCanvas.h"
#include "TFile.h"
#include "TStyle.h"
#include "TSystem.h"
 
#ifndef INT_MAX
#define INT_MAX std::numeric_limits<int>::max()
#endif
 
class TTimeHists {
public:
   enum EHist { kHist, kSparse, kNumHist };
   enum ETime { kReal, kCPU, kNumTime };
   TTimeHists(Int_t dim, Int_t bins, Long_t num):
      fValue(nullptr), fDim(dim), fBins(bins), fNum(num),
      fSparse(nullptr), fHist(nullptr), fHn(nullptr) {}
   ~TTimeHists();
   bool Run();
   Double_t GetTime(EHist hist, ETime time) const {
      if (time == kReal) return fTime[hist][0];
      return fTime[hist][1]; }
   static void SetDebug(Int_t lvl) { fgDebug = lvl; }
   THnSparse* GetSparse() const { return fSparse; }
 
protected:
   void Fill(EHist hist);
   Double_t Check(EHist hist);
   void SetupHist(EHist hist);
   void NextValues();
   void SetupValues();
 
private:
   Double_t* fValue;
   Int_t fDim;
   Int_t fBins;
   Long_t fNum;
   Double_t fTime[2][2];
   THnSparse* fSparse;
   TH1*       fHist;
   THn*       fHn;
   static Int_t fgDebug;
};
 
Int_t TTimeHists::fgDebug = 0;
 
TTimeHists::~TTimeHists()
{
   delete [] fValue;
   delete fSparse;
   delete fHist;
   delete fHn;
}
 
bool TTimeHists::Run()
{
   // run all tests with current settings, and check for identity of content.
 
   Double_t check[2];
   Long64_t rep[2];
   for (int h = 0; h < 2; ++h) {
      rep[h] = 0;
      SetupValues();
      try {
         TStopwatch w;
         w.Start();
         SetupHist((EHist) h);
         w.Stop();
         do {
            w.Start(kFALSE);
            Fill((EHist) h);
            check[h] = Check((EHist) h);
            w.Stop();
            ++rep[h];
         } while ((!h && w.RealTime() < 0.1)
            || (h && rep[0] > 0 && rep[1] < rep[0]));
 
         fTime[h][0] = (1.* fNum * rep[h]) / w.RealTime() / 1E6;
         fTime[h][1] = (1.* fNum * rep[h]) / w.CpuTime() / 1E6;
 
         if (h == 1 && (fTime[h][0] > 1E20 || fTime[h][1] > 1E20)) {
            do {
               // some more cycles:
               w.Start(kFALSE);
               Fill((EHist) h);
               Check((EHist) h);
               w.Stop();
               ++rep[h];
            } while (w.RealTime() < 0.1);
 
            fTime[h][0] = (1.* fNum * rep[h]) / w.RealTime() / 1E6;
            fTime[h][1] = (1.* fNum * rep[h]) / w.CpuTime() / 1E6;
         }
 
         if (fTime[h][0] > 1E20) fTime[h][0] = 1E20;
         if (fTime[h][1] > 1E20) fTime[h][1] = 1E20;
      }
      catch (std::exception&) {
         fTime[h][0] = fTime[h][1] = -1.;
         check[h] = -1.; // can never be < 1 without exception
         rep[h] = -1;
      }
   }
   if (check[0] != check[1])
      if (check[0] != -1.)
         printf("ERROR: mismatch of histogram (%g) and sparse histogram (%g) for dim=%d, bins=%d!\n",
                check[0], check[1], fDim, fBins);
      // else
      //   printf("ERROR: cannot allocate histogram for dim=%d, bins=%d - out of memory!\n",
      //          fDim, fBins);
   return (check[0] == check[1]);
}
 
void TTimeHists::NextValues()
{
   for (Int_t d = 0; d < fDim; ++d)
      fValue[d] = gRandom->Gaus() / 4.;
}
 
void TTimeHists::SetupValues()
{
   // define fValue
   if (!fValue) fValue = new Double_t[fDim];
   gRandom->SetSeed(42);
}
 
void TTimeHists::Fill(EHist hist)
{
   for (Long_t n = 0; n < fNum; ++n) {
      NextValues();
      if (fgDebug > 1) {
         printf("%ld: fill %s", n, hist == kHist? (fDim < 4 ? "hist" : "arr") : "sparse");
         for (Int_t d = 0; d < fDim; ++d)
            printf("[%g]", fValue[d]);
         printf("\n");
      }
      if (hist == kHist) {
         switch (fDim) {
         case 1: fHist->Fill(fValue[0]); break;
         case 2: ((TH2F*)fHist)->Fill(fValue[0], fValue[1]); break;
         case 3: ((TH3F*)fHist)->Fill(fValue[0], fValue[1], fValue[2]); break;
         default: fHn->Fill(fValue); break;
         }
      } else {
         fSparse->Fill(fValue);
      }
   }
}
 
void TTimeHists::SetupHist(EHist hist)
{
   if (hist == kHist) {
      switch (fDim) {
      case 1: fHist = new TH1F("h1", "h1", fBins, -1., 1.); break;
      case 2: fHist = new TH2F("h2", "h2", fBins, -1., 1., fBins, -1., 1.); break;
      case 3: fHist = new TH3F("h3", "h3", fBins, -1., 1., fBins, -1., 1., fBins, -1., 1.); break;
      default:
         {
            MemInfo_t meminfo;
            gSystem->GetMemInfo(&meminfo);
            Int_t size = 1;
            for (Int_t d = 0; d < fDim; ++d) {
               if ((Int_t)(size * sizeof(Float_t)) > INT_MAX / (fBins + 2)
                  || (meminfo.fMemFree > 0
                  && meminfo.fMemFree / 2 < (Int_t) (size * sizeof(Float_t)/1000/1000)))
                  throw std::bad_alloc();
               size *= (fBins + 2);
            }
            if (meminfo.fMemFree > 0
               && meminfo.fMemFree / 2 < (Int_t) (size * sizeof(Float_t)/1000/1000))
               throw std::bad_alloc();
            Int_t* bins = new Int_t[fDim];
            Double_t *xmin = new Double_t[fDim];
            Double_t *xmax = new Double_t[fDim];
            for (Int_t d = 0; d < fDim; ++d) {
               bins[d] = fBins;
               xmin[d] = -1.;
               xmax[d] =  1.;
            }
            fHn = new THnF("hn", "hn", fDim, bins, xmin, xmax);
         }
      }
   } else {
      Int_t* bins = new Int_t[fDim];
      Double_t *xmin = new Double_t[fDim];
      Double_t *xmax = new Double_t[fDim];
      for (Int_t d = 0; d < fDim; ++d) {
         bins[d] = fBins;
         xmin[d] = -1.;
         xmax[d] =  1.;
      }
      fSparse = new THnSparseF("hs", "hs", fDim, bins, xmin, xmax);
   }
}
 
Double_t TTimeHists::Check(EHist hist)
{
   // Check bin content of all bins
   Double_t check = 0.;
   Int_t* x = new Int_t[fDim];
   memset(x, 0, sizeof(Int_t) * fDim);
 
   if (hist == kHist) {
      Long_t idx = 0;
      Long_t size = 1;
      for (Int_t d = 0; d < fDim; ++d)
         size *= (fBins + 2);
      while (x[0] <= fBins + 1) {
         Double_t v = -1.;
         if (fDim < 4) {
            Long_t histidx = x[0];
            if (fDim == 2) histidx = fHist->GetBin(x[0], x[1]);
            else if (fDim == 3) histidx = fHist->GetBin(x[0], x[1], x[2]);
            v = fHist->GetBinContent(histidx);
         }
         else v = fHn->GetBinContent(x);
         Double_t checkx = 0.;
         if (v)
            for (Int_t d = 0; d < fDim; ++d)
               checkx += x[d];
         check += checkx * v;
 
         if (fgDebug > 2 || (fgDebug > 1 && v)) {
            printf("%s%d", fDim < 4 ? "hist" : "arr", fDim);
            for (Int_t d = 0; d < fDim; ++d)
               printf("[%d]", x[d]);
            printf(" = %g\n", v);
         }
 
         ++x[fDim - 1];
         // Adjust the bin idx
         // no wrapping for dim 0 - it's what we break on!
         for (Int_t d = fDim - 1; d > 0; --d) {
            if (x[d] > fBins + 1) {
               x[d] = 0;
               ++x[d - 1];
            }
         }
         ++idx;
      } // while next bin
   } else {
      for (Long64_t i = 0; i < fSparse->GetNbins(); ++i) {
         Double_t v = fSparse->GetBinContent(i, x);
         Double_t checkx = 0.;
         for (Int_t d = 0; d < fDim; ++d)
            checkx += x[d];
         check += checkx * v;
 
         if (fgDebug > 1) {
            printf("sparse%d", fDim);
            for (Int_t d = 0; d < fDim; ++d)
               printf("[%d]", x[d]);
            printf(" = %g\n", v);
         }
      }
   }
   check /= fNum;
   if (fgDebug > 0)
      printf("check %s%d = %g\n", hist == kHist ? (fDim < 4 ? "hist" : "arr") : "sparse", fDim, check);
   return check;
}
 
 
void sparsehist() {
// Exclude this macro also for Cling as this script requires exception support
// which is not supported in Cling as of v6.00/00.
#if defined (__CLING__)
   printf("Please run this script in compiled mode by running \".x sparsehist.C+\"\n");
   return;
#endif
 
   TH2F* htime[TTimeHists::kNumHist][TTimeHists::kNumTime];
   for (int h = 0; h < TTimeHists::kNumHist; ++h)
      for (int t = 0; t < TTimeHists::kNumTime; ++t) {
         TString name("htime_");
         if (h == 0) name += "arr";
         else name += "sp";
         if (t == 0) name += "_r";
 
         TString title;
         title.Form("Throughput (fill,get) %s (%s, 1M entries/sec);dim;bins;1M entries/sec", h == 0 ? "TH1/2/3/nF" : "THnSparseF", t == 0 ? "real" : "CPU");
         htime[h][t] = new TH2F(name, title, 6, 0.5, 6.5, 10, 5, 105);
      }
 
   TH2F* hsparse_mem = new TH2F("hsparse_mem", "Fractional memory usage;dim;bins;fraction of memory used", 6, 0.5, 6.5, 10, 5, 105);
   TH2F* hsparse_bins = new TH2F("hsparse_bins", "Fractional number of used bins;dim;bins;fraction of filled bins", 6, 0.5, 6.5, 10, 5, 105);
 
   // TTimeHists::SetDebug(2);
   Double_t max = -1.;
   for (Int_t dim = 1; dim < 7; ++dim) {
      printf("Processing dimension %d", dim);
      for (Int_t bins = 10; bins <= 100; bins += 10) {
         TTimeHists timer(dim, bins, /*num*/ 1000);
         timer.Run();
         for (int h = 0; h < TTimeHists::kNumHist; ++h) {
            for (int t = 0; t < TTimeHists::kNumTime; ++t) {
               Double_t time = timer.GetTime((TTimeHists::EHist)h, (TTimeHists::ETime)t);
               if (time >= 0.)
                  htime[h][t]->Fill(dim, bins, time);
            }
         }
         hsparse_mem->Fill(dim, bins, timer.GetSparse()->GetSparseFractionMem());
         hsparse_bins->Fill(dim, bins, timer.GetSparse()->GetSparseFractionBins());
 
         if (max < timer.GetTime(TTimeHists::kSparse, TTimeHists::kReal))
            max = timer.GetTime(TTimeHists::kSparse, TTimeHists::kReal);
         printf(".");
         fflush(stdout);
      }
      printf(" done\n");
   }
 
   Double_t markersize = 2.5;
   hsparse_mem->SetMarkerSize(markersize);
   hsparse_bins->SetMarkerSize(markersize);
 
   TH2F* htime_ratio[TTimeHists::kNumTime];
   for (int t = 0; t < TTimeHists::kNumTime; ++t) {
      const char* name = t ? "htime_ratio" : "htime_ratio_r";
      htime_ratio[t] = (TH2F*) htime[TTimeHists::kSparse][t]->Clone(name);
      TString title;
      title.Form("Relative speed improvement (%s, 1M entries/sec): sparse/hist;dim;bins;#Delta 1M entries/sec", t == 0 ? "real" : "CPU");
      htime_ratio[t]->SetTitle(title);
      htime_ratio[t]->Divide(htime[TTimeHists::kHist][t]);
      htime_ratio[t]->SetMinimum(0.1);
      htime_ratio[t]->SetMarkerSize(markersize);
   }
 
   TFile* f = new TFile("sparsehist.root","RECREATE");
 
   TCanvas* canv= new TCanvas("c","c");
   canv->Divide(3,3);
 
   gStyle->SetPalette(8,nullptr);
   gStyle->SetPaintTextFormat(".2g");
   gStyle->SetOptStat(0);
   const char* opt = "TEXT COL";
 
   for (int t = 0; t < TTimeHists::kNumTime; ++t) {
      for (int h = 0; h < TTimeHists::kNumHist; ++h) {
         htime[h][t]->SetMaximum(max);
         htime[h][t]->SetMarkerSize(markersize);
         canv->cd(1 + h + 3 * t);
         htime[h][t]->Draw(opt);
         htime[h][t]->Write();
      }
      canv->cd(3 + t * 3);
      htime_ratio[t]->Draw(opt); gPad->SetLogz();
      htime_ratio[t]->Write();
   }
 
   canv->cd(7); hsparse_mem->Draw(opt);
   canv->cd(8); hsparse_bins->Draw(opt);
   hsparse_mem->Write();
   hsparse_bins->Write();
 
   canv->Write();
 
   delete f;
}

Author

Axel.Naumann

Definition in file sparsehist.C.