src/vm/cycles-stats.c

   1 /* src/vm/cycles-stats.c - functions for cycle count statistics
   2
   3    Copyright (C) 1996-2005, 2006 R. Grafl, A. Krall, C. Kruegel,
   4    C. Oates, R. Obermaisser, M. Platter, M. Probst, S. Ring,
   5    E. Steiner, C. Thalinger, D. Thuernbeck, P. Tomsich, C. Ullrich,
   6    J. Wenninger, Institut f. Computersprachen - TU Wien
   7
   8    This file is part of CACAO.
   9
  10    This program is free software; you can redistribute it and/or
  11    modify it under the terms of the GNU General Public License as
  12    published by the Free Software Foundation; either version 2, or (at
  13    your option) any later version.
  14
  15    This program is distributed in the hope that it will be useful, but
  16    WITHOUT ANY WARRANTY; without even the implied warranty of
  17    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  18    General Public License for more details.
  19
  20    You should have received a copy of the GNU General Public License
  21    along with this program; if not, write to the Free Software
  22    Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
  23    02110-1301, USA.
  24
  25    Contact: cacao@cacaojvm.org
  26
  27    Authors: Edwin Steiner
  28
  29    Changes:
  30
  31 */
  32
  33 #include "config.h"
  34 #include "vm/types.h"
  35 #include "vm/global.h"
  36
  37 #if defined(ENABLE_CYCLES_STATS)
  38
  39 #include <stdio.h>
  40 #include <errno.h>
  41 #include <string.h>
  42 #include <assert.h>
  43 #include "vm/cycles-stats.h"
  44
  45 struct cycles_stats_percentile {
  46         int         pct;
  47         const char *name;
  48 };
  49
  50 static struct cycles_stats_percentile cycles_stats_percentile_defs[] = {
  51         { 10, "10%-percentile" },
  52         { 50, "median"         },
  53         { 90, "90%-percentile" },
  54         { 99, "99%-percentile" },
  55         {  0, NULL             } /* sentinel */
  56 };
  57
  58 static double cycles_stats_cpu_MHz = 0.0;
  59
  60 #define CYCLES_STATS_MAXLINE  100
  61
  62 static double cycles_stats_get_cpu_MHz(void)
  63 {
  64         FILE *info;
  65         char line[CYCLES_STATS_MAXLINE + 1];
  66
  67         if (cycles_stats_cpu_MHz != 0.0)
  68                 return cycles_stats_cpu_MHz;
  69
  70         info = fopen("/proc/cpuinfo","r");
  71         if (!info) {
  72                 fprintf(stderr,"error: could not open /proc/cpuinfo: %s\n",strerror(errno));
  73                 goto got_no_cpuinfo;
  74         }
  75
  76         while (!feof(info) && !ferror(info)) {
  77                 if (fgets(line,CYCLES_STATS_MAXLINE,info)
  78                         && sscanf(line,"cpu MHz : %lf",&cycles_stats_cpu_MHz) == 1)
  79                 {
  80                         fclose(info);
  81                         fprintf(stderr,"CPU frequency used for statistics: %f MHz\n",
  82                                         cycles_stats_cpu_MHz);
  83                         return cycles_stats_cpu_MHz;
  84                 }
  85         }
  86
  87         if (ferror(info)) {
  88                 fprintf(stderr,"error reading /proc/cpuinfo: %s\n",strerror(errno));
  89         }
  90
  91         fclose(info);
  92
  93 got_no_cpuinfo:
  94         fprintf(stderr,"warning: falling back to default CPU frequency for statistics\n");
  95         cycles_stats_cpu_MHz = 1800.0;
  96         return cycles_stats_cpu_MHz;
  97 }
  98
  99 u8 cycles_stats_measurement_overhead = 0;
 100
 101 static void cycles_stats_print_percentile(FILE *file, const char *name,
 102                                                                                   double percentile, u8 count,
 103                                                                                   u8 cumul, double cumulcycles,
 104                                                                                   bool isoverhead, bool printforall)
 105 {
 106         u8 forall;
 107         double cpuMHz = cycles_stats_get_cpu_MHz();
 108         u8 cycles_per_ms = cpuMHz * 1000;
 109
 110         if (isoverhead) {
 111                 fprintf(file,"\t\t%14s = %6.1f\n", name, percentile);
 112         }
 113         else {
 114                 percentile -= cycles_stats_measurement_overhead;
 115
 116                 fprintf(file,"\t\t%14s = %14.1f (+%llu)",
 117                                 name, percentile,
 118                                 (unsigned long long)cycles_stats_measurement_overhead);
 119                 if (printforall) {
 120                         forall = cumulcycles - cumul * cycles_stats_measurement_overhead
 121                                    + percentile * (count - cumul);
 122                         fprintf(file," (%-23s: %15llu cycles = %6lu msec)",
 123                                         (count == cumul) ? "total" : "capped here & extrapol.",
 124                                         (unsigned long long)forall,
 125                                         (unsigned long)(forall / cycles_per_ms));
 126                 }
 127                 fprintf(file,"\n");
 128         }
 129 }
 130
 131 void cycles_stats_print(FILE *file,
 132                                                 const char *name, int nbins, int div,
 133                                                 u4 *bins, u8 count, u8 total, u8 min, u8 max,
 134                                                 int overhead)
 135 {
 136         s4 i;
 137                 struct cycles_stats_percentile *pcd;
 138                 u8 floor, ceiling;
 139                 u8 p;
 140                 u8 cumul;
 141                 double cumulcycles;
 142                 double percentile;
 143                 double cpuMHz = cycles_stats_get_cpu_MHz();
 144                 u8 cycles_per_ms = cpuMHz * 1000;
 145
 146         fprintf(file,"\t%s: %llu calls\n",
 147                 (overhead) ? "measurement overhead determined by" : name,
 148                                 (unsigned long long)count);
 149
 150         fprintf(file,"\t%s cycles distribution:\n",
 151                                 (overhead) ? "measurement overhead" : name);
 152
 153                 cycles_stats_print_percentile(file, "min", min, count, 0, 0, overhead, true);
 154
 155                 pcd = cycles_stats_percentile_defs;
 156                 for (; pcd->name; pcd++) {
 157                         floor   = (count * pcd->pct) / 100;
 158                         ceiling = (count * pcd->pct + 99) / 100;
 159                         cumul = 0;
 160                         cumulcycles = 0;
 161                         p = 0;
 162                         percentile = -1.0;
 163
 164                         assert( ceiling <= floor + 1 );
 165
 166                         for (i=0; i<nbins; ++i) {
 167
 168                                 /* { invariant: `cumul` samples are < `p` } */
 169
 170                                 /* check if percentile lies exactly at the bin boundary */
 171
 172                                 if (floor == cumul && floor == ceiling) {
 173                                         percentile = p;
 174                                         break;
 175                                 }
 176
 177                                 /* check if percentile lies within this bin */
 178
 179                                 if (cumul <= floor && ceiling <= cumul + bins[i]) {
 180                                         percentile = p + (double)div/2.0;
 181                                         break;
 182                                 }
 183
 184                                 cumul += bins[i];
 185                                 p     += div;
 186
 187                                 cumulcycles += bins[i] * (p - (double)div/2.0);
 188
 189                                 /* { invariant: `cumul` samples are < `p` } */
 190                         }
 191
 192                         /* check if percentile lies exactly at the bin boundary */
 193
 194                         if (floor == cumul && floor == ceiling) {
 195                                 percentile = p;
 196                         }
 197
 198                         if (percentile >= 0) {
 199                                 if (overhead && pcd->pct == 50) {
 200                                         cycles_stats_measurement_overhead = percentile;
 201                                 }
 202                                 cycles_stats_print_percentile(file, pcd->name, percentile,
 203                                                                                           count, cumul, cumulcycles,
 204                                                                                           overhead, true);
 205                         }
 206                         else {
 207                                 if (!overhead)
 208                                         p -= cycles_stats_measurement_overhead;
 209                                 fprintf(file,"\t\t%14s = unknown (> %llu)\n", pcd->name, (unsigned long long)p);
 210                         }
 211                 }
 212
 213                 cycles_stats_print_percentile(file, "max", max, count, count,
 214                                                                           total, overhead, true);
 215
 216                 if (!overhead) {
 217                         fprintf(file,"\t\t(assuming %llu cycles per ms)\n",
 218                                         (unsigned long long)cycles_per_ms);
 219                         fprintf(file,"\t\t(assuming %llu cycles measurement overhead)\n",
 220                                         (unsigned long long)cycles_stats_measurement_overhead);
 221                 }
 222
 223                 fprintf(file,"\n");
 224
 225                 cumul = 0;
 226         for (i=0; i<nbins; ++i) {
 227                         cumul += bins[i];
 228             fprintf(file,"\t\t<  %8d: %10lu (%3d%%) %10lu\n",
 229                     (int)((i+1) * div),
 230                                         (unsigned long) cumul,
 231                                         (count) ? (int)((cumul * 100) / count) : 0,
 232                     (unsigned long) bins[i]);
 233         }
 234
 235         fprintf(file,"\t\t>= %8d: %10s (----) %10lu\n",
 236                 (int)(nbins * div),
 237                                 "OVER",
 238                 (unsigned long) bins[nbins]);
 239 }
 240
 241 #endif /* defined(ENABLE_CYCLES_STATS) */
 242
 243 /*
 244  * These are local overrides for various environment variables in Emacs.
 245  * Please do not remove this and leave it at the end of the file, where
 246  * Emacs will automagically detect them.
 247  * ---------------------------------------------------------------------
 248  * Local variables:
 249  * mode: c
 250  * indent-tabs-mode: t
 251  * c-basic-offset: 4
 252  * tab-width: 4
 253  * End:
 254  * vim:noexpandtab:sw=4:ts=4:
 255  */