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 #if defined (__i386__) || defined (__x86_64__)
  18 #include <xmmintrin.h>
  19 #endif
  20
  21 #include "runtime.h"
  22
  23 /* Spin wait.  */
  24
  25 void
  26 runtime_procyield (uint32 cnt)
  27 {
  28   volatile uint32 i;
  29
  30   for (i = 0; i < cnt; ++i)
  31     {
  32 #if defined (__i386__) || defined (__x86_64__)
  33       _mm_pause ();
  34 #endif
  35     }
  36 }
  37
  38 /* Ask the OS to reschedule this thread.  */
  39
  40 void runtime_osyield(void)
  41   __attribute__ ((no_split_stack));
  42
  43 void
  44 runtime_osyield (void)
  45 {
  46   sched_yield ();
  47 }
  48
  49 /* Sleep for some number of microseconds.  */
  50
  51 void
  52 runtime_usleep (uint32 us)
  53 {
  54   struct timeval tv;
  55
  56   tv.tv_sec = us / 1000000;
  57   tv.tv_usec = us % 1000000;
  58   select (0, NULL, NULL, NULL, &tv);
  59 }