libgo/runtime/getncpu-linux.c

   1 // Copyright 2012 The Go Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style
   3 // license that can be found in the LICENSE file.
   4
   5 #include <features.h>
   6 #include <sched.h>
   7
   8 // CPU_COUNT is only provided by glibc 2.6 or higher
   9 #ifndef CPU_COUNT
  10 #define CPU_COUNT(set) _CPU_COUNT((unsigned int *)(set), sizeof(*(set))/sizeof(unsigned int))
  11 static int _CPU_COUNT(unsigned int *set, size_t len) {
  12         int cnt;
  13
  14         cnt = 0;
  15         while (len--)
  16                 cnt += __builtin_popcount(*set++);
  17         return cnt;
  18 }
  19 #endif
  20
  21 #include "runtime.h"
  22 #include "defs.h"
  23
  24 int32
  25 getproccount(void)
  26 {
  27         cpu_set_t set;
  28         int32 r, cnt;
  29
  30         cnt = 0;
  31         r = sched_getaffinity(0, sizeof(set), &set);
  32         if(r == 0)
  33                 cnt += CPU_COUNT(&set);
  34
  35         return cnt ? cnt : 1;
  36 }