libgo/runtime/yield.c

   1 // Copyright 2011 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 "config.h"
   6
   7 #include <stddef.h>
   8 #include <sys/types.h>
   9 #include <sys/time.h>
  10 #include <sched.h>
  11 #include <unistd.h>
  12
  13 #ifdef HAVE_SYS_SELECT_H
  14 #include <sys/select.h>
  15 #endif
  16
  17 #include "runtime.h"
  18
  19 /* Spin wait.  */
  20
  21 void
  22 runtime_procyield (uint32 cnt)
  23 {
  24   volatile uint32 i;
  25
  26   for (i = 0; i < cnt; ++i)
  27     {
  28 #if defined (__i386__) || defined (__x86_64__)
  29       __builtin_ia32_pause ();
  30 #endif
  31     }
  32 }
  33
  34 /* Ask the OS to reschedule this thread.  */
  35
  36 void
  37 runtime_osyield (void)
  38 {
  39   sched_yield ();
  40 }
  41
  42 /* Sleep for some number of microseconds.  */
  43
  44 void
  45 runtime_usleep (uint32 us)
  46 {
  47   struct timeval tv;
  48
  49   tv.tv_sec = us / 1000000;
  50   tv.tv_usec = us % 1000000;
  51   select (0, NULL, NULL, NULL, &tv);
  52 }