tools/perf/util/cpumap.c

   1 #include "util.h"
   2 #include "../perf.h"
   3 #include "cpumap.h"
   4 #include <assert.h>
   5 #include <stdio.h>
   6
   7 int cpumap[MAX_NR_CPUS];
   8
   9 static int default_cpu_map(void)
  10 {
  11         int nr_cpus, i;
  12
  13         nr_cpus = sysconf(_SC_NPROCESSORS_ONLN);
  14         assert(nr_cpus <= MAX_NR_CPUS);
  15         assert((int)nr_cpus >= 0);
  16
  17         for (i = 0; i < nr_cpus; ++i)
  18                 cpumap[i] = i;
  19
  20         return nr_cpus;
  21 }
  22
  23 int read_cpu_map(void)
  24 {
  25         FILE *onlnf;
  26         int nr_cpus = 0;
  27         int n, cpu, prev;
  28         char sep;
  29
  30         onlnf = fopen("/sys/devices/system/cpu/online", "r");
  31         if (!onlnf)
  32                 return default_cpu_map();
  33
  34         sep = 0;
  35         prev = -1;
  36         for (;;) {
  37                 n = fscanf(onlnf, "%u%c", &cpu, &sep);
  38                 if (n <= 0)
  39                         break;
  40                 if (prev >= 0) {
  41                         assert(nr_cpus + cpu - prev - 1 < MAX_NR_CPUS);
  42                         while (++prev < cpu)
  43                                 cpumap[nr_cpus++] = prev;
  44                 }
  45                 assert (nr_cpus < MAX_NR_CPUS);
  46                 cpumap[nr_cpus++] = cpu;
  47                 if (n == 2 && sep == '-')
  48                         prev = cpu;
  49                 else
  50                         prev = -1;
  51                 if (n == 1 || sep == '\n')
  52                         break;
  53         }
  54         fclose(onlnf);
  55         if (nr_cpus > 0)
  56                 return nr_cpus;
  57
  58         return default_cpu_map();
  59 }