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    $Id$
  32
  33 */
  34
  35 #include "config.h"
  36 #include "vm/types.h"
  37 #include "vm/global.h"
  38
  39 #if defined(ENABLE_CYCLES_STATS)
  40
  41 #include <stdio.h>
  42 #include <errno.h>
  43 #include <string.h>
  44 #include <assert.h>
  45 #include "vm/cycles-stats.h"
  46
  47 struct cycles_stats_percentile {
  48         int         pct;
  49         const char *name;
  50 };
  51
  52 static struct cycles_stats_percentile cycles_stats_percentile_defs[] = {
  53         { 10, "10%-percentile" },
  54         { 50, "median"         },
  55         { 90, "90%-percentile" },
  56         { 99, "99%-percentile" },
  57         {  0, NULL             } /* sentinel */
  58 };
  59
  60 static double cycles_stats_cpu_MHz = 0.0;
  61
  62 #define CYCLES_STATS_MAXLINE  100
  63
  64 static double cycles_stats_get_cpu_MHz(void)
  65 {
  66         FILE *info;
  67         char line[CYCLES_STATS_MAXLINE + 1];
  68
  69         if (cycles_stats_cpu_MHz != 0.0)
  70                 return cycles_stats_cpu_MHz;
  71
  72         info = fopen("/proc/cpuinfo","r");
  73         if (!info) {
  74                 fprintf(stderr,"error: could not open /proc/cpuinfo: %s\n",strerror(errno));
  75                 goto got_no_cpuinfo;
  76         }
  77
  78         while (!feof(info) && !ferror(info)) {
  79                 if (fgets(line,CYCLES_STATS_MAXLINE,info)
  80                         && sscanf(line,"cpu MHz : %lf",&cycles_stats_cpu_MHz) == 1)
  81                 {
  82                         fclose(info);
  83                         fprintf(stderr,"CPU frequency used for statistics: %f MHz\n",
  84                                         cycles_stats_cpu_MHz);
  85                         return cycles_stats_cpu_MHz;
  86                 }
  87         }
  88
  89         if (ferror(info)) {
  90                 fprintf(stderr,"error reading /proc/cpuinfo: %s\n",strerror(errno));
  91         }
  92
  93         fclose(info);
  94
  95 got_no_cpuinfo:
  96         fprintf(stderr,"warning: falling back to default CPU frequency for statistics\n");
  97         cycles_stats_cpu_MHz = 1800.0;
  98         return cycles_stats_cpu_MHz;
  99 }
 100
 101 u8 cycles_stats_measurement_overhead = 0;
 102
 103 static void cycles_stats_print_percentile(FILE *file, const char *name,
 104                                                                                   double percentile, u8 count,
 105                                                                                   u8 cumul, double cumulcycles,
 106                                                                                   bool isoverhead, bool printforall)
 107 {
 108         u8 forall;
 109         double cpuMHz = cycles_stats_get_cpu_MHz();
 110         u8 cycles_per_ms = cpuMHz * 1000;
 111
 112         if (isoverhead) {
 113                 fprintf(file,"\t\t%14s = %6.1f\n", name, percentile);
 114         }
 115         else {
 116                 percentile -= cycles_stats_measurement_overhead;
 117
 118                 fprintf(file,"\t\t%14s = %14.1f (+%llu)",
 119                                 name, percentile,
 120                                 (unsigned long long)cycles_stats_measurement_overhead);
 121                 if (printforall) {
 122                         forall = cumulcycles + percentile * (count - cumul);
 123                         fprintf(file," (%-23s: %15llu cycles = %6lu msec)",
 124                                         (count == cumul) ? "total" : "capped here & extrapol.",
 125                                         (unsigned long long)forall,
 126                                         (unsigned long)(forall / cycles_per_ms));
 127                 }
 128                 fprintf(file,"\n");
 129         }
 130 }
 131
 132 void cycles_stats_print(FILE *file,
 133                                                 const char *name, int nbins, int div,
 134                                                 u4 *bins, u8 count, u8 total, u8 min, u8 max,
 135                                                 int overhead)
 136 {
 137         s4 i;
 138                 struct cycles_stats_percentile *pcd;
 139                 u8 floor, ceiling;
 140                 u8 p;
 141                 u8 cumul;
 142                 double cumulcycles;
 143                 double percentile;
 144                 double cpuMHz = cycles_stats_get_cpu_MHz();
 145                 u8 cycles_per_ms = cpuMHz * 1000;
 146
 147         fprintf(file,"\t%s: %llu calls\n",
 148                 (overhead) ? "measurement overhead determined by" : name,
 149                                 (unsigned long long)count);
 150
 151         fprintf(file,"\t%s cycles distribution:\n",
 152                                 (overhead) ? "measurement overhead" : name);
 153
 154                 cycles_stats_print_percentile(file, "min", min, count, 0, 0, overhead, true);
 155
 156                 pcd = cycles_stats_percentile_defs;
 157                 for (; pcd->name; pcd++) {
 158                         floor   = (count * pcd->pct) / 100;
 159                         ceiling = (count * pcd->pct + 99) / 100;
 160                         cumul = 0;
 161                         cumulcycles = 0;
 162                         p = 0;
 163                         percentile = -1.0;
 164
 165                         assert( ceiling <= floor + 1 );
 166
 167                         for (i=0; i<nbins; ++i) {
 168
 169                                 /* { invariant: `cumul` samples are < `p` } */
 170
 171                                 /* check if percentile lies exactly at the bin boundary */
 172
 173                                 if (floor == cumul && floor == ceiling) {
 174                                         percentile = p;
 175                                         break;
 176                                 }
 177
 178                                 /* check if percentile lies within this bin */
 179
 180                                 if (cumul <= floor && ceiling <= cumul + bins[i]) {
 181                                         percentile = p + (double)div/2.0;
 182                                         break;
 183                                 }
 184
 185                                 cumul += bins[i];
 186                                 p     += div;
 187
 188                                 cumulcycles += bins[i] * (p - (double)div/2.0);
 189
 190                                 /* { invariant: `cumul` samples are < `p` } */
 191                         }
 192
 193                         /* check if percentile lies exactly at the bin boundary */
 194
 195                         if (floor == cumul && floor == ceiling) {
 196                                 percentile = p;
 197                         }
 198
 199                         if (percentile >= 0) {
 200                                 if (overhead && pcd->pct == 50) {
 201                                         cycles_stats_measurement_overhead = percentile;
 202                                 }
 203                                 cycles_stats_print_percentile(file, pcd->name, percentile,
 204                                                                                           count, cumul, cumulcycles,
 205                                                                                           overhead, true);
 206                         }
 207                         else {
 208                                 if (!overhead)
 209                                         p -= cycles_stats_measurement_overhead;
 210                                 fprintf(file,"\t\t%14s = unknown (> %llu)\n", pcd->name, (unsigned long long)p);
 211                         }
 212                 }
 213
 214                 cycles_stats_print_percentile(file, "max", max, count, count,
 215                                                                           total, overhead, true);
 216
 217                 if (!overhead) {
 218                         fprintf(file,"\t\t(assuming %llu cycles per ms)\n",
 219                                         (unsigned long long)cycles_per_ms);
 220                         fprintf(file,"\t\t(assuming %llu cycles measurement overhead)\n",
 221                                         (unsigned long long)cycles_stats_measurement_overhead);
 222                 }
 223
 224                 fprintf(file,"\n");
 225
 226                 cumul = 0;
 227         for (i=0; i<nbins; ++i) {
 228                         cumul += bins[i];
 229             fprintf(file,"\t\t<  %5d: %10lu (%3d%%) %10lu\n",
 230                     (int)((i+1) * div),
 231                                         (unsigned long) cumul,
 232                                         (int)((cumul * 100) / count),
 233                     (unsigned long) bins[i]);
 234         }
 235
 236         fprintf(file,"\t\t>= %5d: %10s (----) %10lu\n",
 237                 (int)(nbins * div),
 238                                 "OVER",
 239                 (unsigned long) bins[nbins]);
 240 }
 241
 242 #endif /* defined(ENABLE_CYCLES_STATS) */
 243
 244 /*
 245  * These are local overrides for various environment variables in Emacs.
 246  * Please do not remove this and leave it at the end of the file, where
 247  * Emacs will automagically detect them.
 248  * ---------------------------------------------------------------------
 249  * Local variables:
 250  * mode: c
 251  * indent-tabs-mode: t
 252  * c-basic-offset: 4
 253  * tab-width: 4
 254  * End:
 255  * vim:noexpandtab:sw=4:ts=4:
 256  */