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 #define _GNU_SOURCE
   6
   7 #include "config.h"
   8
   9 #include <stddef.h>
  10 #include <sys/types.h>
  11 #include <sys/time.h>
  12 #include <sched.h>
  13 #include <unistd.h>
  14
  15 #ifdef HAVE_SYS_SELECT_H
  16 #include <sys/select.h>
  17 #endif
  18
  19 #include "runtime.h"
  20
  21 /* Spin wait.  */
  22
  23 void
  24 runtime_procyield (uint32 cnt)
  25 {
  26   volatile uint32 i;
  27
  28   for (i = 0; i < cnt; ++i)
  29     {
  30 #if defined (__i386__) || defined (__x86_64__)
  31       __builtin_ia32_pause ();
  32 #endif
  33     }
  34 }
  35
  36 /* Ask the OS to reschedule this thread.  */
  37
  38 void
  39 runtime_osyield (void)
  40 {
  41   sched_yield ();
  42 }
  43
  44 /* Sleep for some number of microseconds.  */
  45
  46 void
  47 runtime_usleep (uint32 us)
  48 {
  49   struct timeval tv;
  50
  51   tv.tv_sec = us / 1000000;
  52   tv.tv_usec = us % 1000000;
  53   select (0, NULL, NULL, NULL, &tv);
  54 }