From cd758dd0acaaf1f76f9727d4409915f3293db07a Mon Sep 17 00:00:00 2001
From: Alex Bligh <alex@alex.org.uk>
Date: Wed, 21 Aug 2013 16:02:44 +0100
Subject: aio / timers: Add prctl(PR_SET_TIMERSLACK, 1, ...) to reduce timer
 slack

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>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
---
 qemu-timer.c | 7 +++++++
 1 file changed, 7 insertions(+)

(limited to 'qemu-timer.c')

diff --git a/qemu-timer.c b/qemu-timer.c
index 120d58fb2a..74f904b310 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 */
 
@@ -507,6 +511,9 @@ void init_clocks(void)
         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 timer_expire_time_ns(QEMUTimer *ts)
-- 
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