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view m4/ceilf.m4 @ 16869:38e6d30d7e4d
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 | b187fc49964b |
children | e542fd46ad6f |
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# ceilf.m4 serial 14 dnl Copyright (C) 2007, 2009-2012 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_CEILF], [ m4_divert_text([DEFAULTS], [gl_ceilf_required=plain]) AC_REQUIRE([gl_MATH_H_DEFAULTS]) dnl Persuade glibc <math.h> to declare ceilf(). AC_REQUIRE([gl_USE_SYSTEM_EXTENSIONS]) dnl Test whether ceilf() is declared. AC_CHECK_DECLS([ceilf], , , [[#include <math.h>]]) if test "$ac_cv_have_decl_ceilf" = yes; then dnl Test whether ceilf() can be used without libm. gl_FUNC_CEILF_LIBS if test "$CEILF_LIBM" = "?"; then dnl Sun C 5.0 on Solaris declares ceilf() and has it in the system-wide dnl libm.so, but not in the libm.so that the compiler uses. REPLACE_CEILF=1 fi m4_ifdef([gl_FUNC_CEILF_IEEE], [ if test $gl_ceilf_required = ieee && test $REPLACE_CEILF = 0; then AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles AC_CACHE_CHECK([whether ceilf works according to ISO C 99 with IEC 60559], [gl_cv_func_ceilf_ieee], [ save_LIBS="$LIBS" LIBS="$LIBS $CEILF_LIBM" AC_RUN_IFELSE( [AC_LANG_SOURCE([[ #ifndef __NO_MATH_INLINES # define __NO_MATH_INLINES 1 /* for glibc */ #endif #include <math.h> ]gl_FLOAT_MINUS_ZERO_CODE[ ]gl_FLOAT_SIGNBIT_CODE[ static float dummy (float f) { return 0; } int main (int argc, char *argv[]) { float (*my_ceilf) (float) = argc ? ceilf : dummy; int result = 0; /* Test whether ceilf (-0.0f) is -0.0f. */ if (signbitf (minus_zerof) && !signbitf (my_ceilf (minus_zerof))) result |= 1; /* Test whether ceilf (-0.3f) is -0.0f. */ if (signbitf (-0.3f) && !signbitf (my_ceilf (-0.3f))) result |= 2; return result; } ]])], [gl_cv_func_ceilf_ieee=yes], [gl_cv_func_ceilf_ieee=no], [case "$host_os" in # Guess yes on glibc systems. *-gnu*) gl_cv_func_ceilf_ieee="guessing yes" ;; # If we don't know, assume the worst. *) gl_cv_func_ceilf_ieee="guessing no" ;; esac ]) LIBS="$save_LIBS" ]) case "$gl_cv_func_ceilf_ieee" in *yes) ;; *) REPLACE_CEILF=1 ;; esac fi ]) else HAVE_DECL_CEILF=0 fi if test $HAVE_DECL_CEILF = 0 || test $REPLACE_CEILF = 1; then dnl No libraries are needed to link lib/ceilf.c. CEILF_LIBM= fi AC_SUBST([CEILF_LIBM]) ]) # Determines the libraries needed to get the ceilf() function. # Sets CEILF_LIBM. AC_DEFUN([gl_FUNC_CEILF_LIBS], [ gl_CACHE_VAL_SILENT([gl_cv_func_ceilf_libm], [ gl_cv_func_ceilf_libm=? AC_LINK_IFELSE( [AC_LANG_PROGRAM( [[#ifndef __NO_MATH_INLINES # define __NO_MATH_INLINES 1 /* for glibc */ #endif #include <math.h> float (*funcptr) (float) = ceilf; float x;]], [[x = funcptr(x) + ceilf(x);]])], [gl_cv_func_ceilf_libm=]) if test "$gl_cv_func_ceilf_libm" = "?"; then save_LIBS="$LIBS" LIBS="$LIBS -lm" AC_LINK_IFELSE( [AC_LANG_PROGRAM( [[#ifndef __NO_MATH_INLINES # define __NO_MATH_INLINES 1 /* for glibc */ #endif #include <math.h> float (*funcptr) (float) = ceilf; float x;]], [[x = funcptr(x) + ceilf(x);]])], [gl_cv_func_ceilf_libm="-lm"]) LIBS="$save_LIBS" fi ]) CEILF_LIBM="$gl_cv_func_ceilf_libm" ])