[Qemu-devel] [RFC] [PATCHv7 05/22] aio / timers: Add prctl(PR_SET_TIMERSLACK, 1, ...) to reduce timer slack

[Alex Bligh <alex@alex.org.uk>]

Where supported, called prctl(PR_SET_TIMERSLACK, 1, ...) to
set one nanosecond timer slack to increase precision of timer
calls.

Signed-off-by: Alex Bligh <alex@alex.org.uk>
---
 qemu-timer.c |   13 ++++++++++---
 1 file changed, 10 insertions(+), 3 deletions(-)

diff --git a/qemu-timer.c b/qemu-timer.c
index 3109bd8..7ad05fb 100644
--- a/qemu-timer.c
+++ b/qemu-timer.c
@@ -41,6 +41,10 @@
 #include <poll.h>
 #endif
 
+#ifdef CONFIG_PRCTL_PR_SET_TIMERSLACK
+#include <sys/prctl.h>
+#endif
+
 /***********************************************************/
 /* timers */
 
@@ -508,10 +512,13 @@ void qemu_unregister_clock_reset_notifier(QEMUClock *clock, Notifier *notifier)
 void init_clocks(void)
 {
     if (!rt_clock) {
-        rt_clock = qemu_new_clock(QEMU_CLOCK_REALTIME);
-        vm_clock = qemu_new_clock(QEMU_CLOCK_VIRTUAL);
-        host_clock = qemu_new_clock(QEMU_CLOCK_HOST);
+        rt_clock = qemu_clock_new(QEMU_CLOCK_REALTIME);
+        vm_clock = qemu_clock_new(QEMU_CLOCK_VIRTUAL);
+        host_clock = qemu_clock_new(QEMU_CLOCK_HOST);
     }
+#ifdef CONFIG_PRCTL_PR_SET_TIMERSLACK
+    prctl(PR_SET_TIMERSLACK, 1, 0, 0, 0);
+#endif
 }
 
 uint64_t qemu_timer_expire_time_ns(QEMUTimer *ts)
-- 
1.7.9.5