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poll/select: prevent busy-waiting 2012-05-21 Paolo Bonzini <bonzini@gnu.org> poll/select: prevent busy-waiting. SwitchToThread() only gives away the rest of the current time slice to another thread in the current process. So if the thread that feeds the file decscriptor we're polling is not in the current process, we get busy-waiting. * lib/poll.c: Use SleepEx(1, TRUE) instead of SwitchToThread(). Patch from Theodore Leblond. * lib/select.c: Split polling out of the loop that sets the output fd_sets. Check for zero result and loop if the wait timeout is infinite.
author Paolo Bonzini <bonzini@gnu.org>
date Mon, 21 May 2012 09:52:42 +0200
parents ca62953d33cd
children e542fd46ad6f
line wrap: on
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# exp2f.m4 serial 1
dnl Copyright (C) 2011-2012 Free Software Foundation, Inc.
dnl This file is free software; the Free Software Foundation
dnl gives unlimited permission to copy and/or distribute it,
dnl with or without modifications, as long as this notice is preserved.

AC_DEFUN([gl_FUNC_EXP2F],
[
  AC_REQUIRE([gl_MATH_H_DEFAULTS])
  AC_REQUIRE([gl_FUNC_EXP2])

  dnl Persuade glibc <math.h> to declare exp2f().
  AC_REQUIRE([gl_USE_SYSTEM_EXTENSIONS])

  dnl Test whether exp2f() exists. Assume that exp2f(), if it exists, is
  dnl defined in the same library as exp2().
  save_LIBS="$LIBS"
  LIBS="$LIBS $EXP2_LIBM"
  AC_CHECK_FUNCS([exp2f])
  LIBS="$save_LIBS"
  if test $ac_cv_func_exp2f = yes; then
    HAVE_EXP2F=1
    EXP2F_LIBM="$EXP2_LIBM"
    dnl Also check whether it's declared.
    dnl IRIX 6.5 has exp2f() in libm but doesn't declare it in <math.h>.
    AC_CHECK_DECL([exp2f], , [HAVE_DECL_EXP2F=0], [[#include <math.h>]])
  else
    HAVE_EXP2F=0
    HAVE_DECL_EXP2F=0
    dnl Find libraries needed to link lib/exp2f.c.
    EXP2F_LIBM="$EXP2_LIBM"
  fi
  AC_SUBST([EXP2F_LIBM])
])