improve responsivness of timer sleeping threads for vsync with prctl

prctl allows us on some platforms to request a thread be woken up more
agressively e.g. due to a timeout bu setting timerslack. since we use
a dedicated thread just for vsync events, this is a very good idea to
ask the kernel to be as exact as possible for this thread as it only
wakes up once per frame (or should only) and accuracy is important. so
use this.

also improve prctl checks to be more explicit in configure.ac and use
these ifdefs in ecore exe too where prctl is used as well.

@feature

configure.ac

@@ -1029,7 +1029,7 @@ EFL_CHECK_GCC_BUILTIN([bswap64], [HAVE_BSWAP64])
 
 AC_CHECK_FUNCS([fchmod])
 
-EFL_CHECK_FUNCS([EINA], [dlopen dladdr iconv shm_open splice setxattr getpagesize])
+EFL_CHECK_FUNCS([EINA], [dlopen dladdr iconv shm_open splice setxattr getpagesize prctl])
 
 enable_log="no"
 if test "x${efl_func_fnmatch}" = "xyes" && test "x${want_log}" = "xyes" ; then

m4/efl_check_funcs.m4

@@ -288,6 +288,17 @@ sz = getpagesize();
 ]])
 ])
 
+dnl _EFL_CHECK_FUNC_PRCTL is for internal use
+dnl _EFL_CHECK_FUNC_PRCTL(EFL, VARIABLE)
+AC_DEFUN([_EFL_CHECK_FUNC_PRCTL],
+[EFL_FIND_LIB_FOR_CODE([$1], [], [$2], [[
+#include <sys/prctl.h>
+]],
+[[
+prctl(PR_SET_TIMERSLACK, 1, 0, 0, 0);
+]])
+])
+
 dnl Macro that checks function availability
 dnl
 dnl EFL_CHECK_FUNC(EFL, FUNCTION)

src/lib/ecore/ecore_anim.c

@@ -30,6 +30,10 @@
 
 #endif /* ! _WIN32 */
 
+#ifdef HAVE_PRCTL
+# include <sys/prctl.h>
+#endif
+
 #include "Ecore.h"
 #include "ecore_private.h"
 
@@ -109,6 +113,9 @@ _timer_tick_core(void *data EINA_UNUSED, Ecore_Thread *thread)
    int ret;
 
    eina_thread_name_set(eina_thread_self(), "Eanimator-timer");
+#ifdef HAVE_PRCTL
+   prctl(PR_SET_TIMERSLACK, 1, 0, 0, 0);
+#endif
    while (!ecore_thread_check(thread))
      {
         DBG("------- timer_event_is_busy=%i", timer_event_is_busy);

src/lib/ecore/ecore_exe_posix.c

@@ -13,7 +13,7 @@
 #include <sys/time.h>
 #include <sys/resource.h>
 
-#ifdef HAVE_SYS_PRCTL_H
+#ifdef HAVE_PRCTL
 # include <sys/prctl.h>
 #endif
 
@@ -1017,11 +1017,11 @@ _ecore_exe_exec_it(const char     *exe_cmd,
       }
    }
 
-#ifdef HAVE_SYS_PRCTL_H
+#ifdef HAVE_PRCTL
    if ((flags & ECORE_EXE_TERM_WITH_PARENT))
-   {
-      prctl(PR_SET_PDEATHSIG, SIGTERM);
-   }
+     {
+        prctl(PR_SET_PDEATHSIG, SIGTERM);
+     }
 #endif
 
    if (!(flags & ECORE_EXE_NOT_LEADER)) setsid();

src/lib/ecore_x/xlib/ecore_x_vsync.c

@@ -17,6 +17,10 @@
 #include <sys/select.h>
 #include <fcntl.h>
 
+#ifdef HAVE_PRCTL
+# include <sys/prctl.h>
+#endif
+
 #define ECORE_X_VSYNC_DRM 1
 
 static Ecore_X_Window vsync_root = 0;
@@ -286,6 +290,9 @@ _drm_tick_core(void *data EINA_UNUSED, Ecore_Thread *thread)
    int tick = 0;
 
    eina_thread_name_set(eina_thread_self(), "Eanimator-vsync");
+#ifdef HAVE_PRCTL
+   prctl(PR_SET_TIMERSLACK, 1, 0, 0, 0);
+#endif
    while (!ecore_thread_check(thread))
      {
         DBG("------- drm_event_is_busy=%i", drm_event_is_busy);