hrtimer: make the nanosleep() syscall use the per process slack

This patch makes the nanosleep() system call use the per process
slack value; with this users are able to externally control existing
applications to reduce the wakeup rate.

Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>

1 files changed, 6 insertions, 1 deletions

diff --git a/kernel/hrtimer.c b/kernel/hrtimer.c
index a0222097c57e..9a4c90185566 100644
--- a/kernel/hrtimer.c
+++ b/kernel/hrtimer.c
@@ -1563,9 +1563,14 @@ long hrtimer_nanosleep(struct timespec *rqtp, struct timespec __user *rmtp,
         struct restart_block *restart;
         struct hrtimer_sleeper t;
         int ret = 0;
+        unsigned long slack;
+
+        slack = current->timer_slack_ns;
+        if (rt_task(current))
+                slack = 0;
 
         hrtimer_init_on_stack(&t.timer, clockid, mode);
-        hrtimer_set_expires(&t.timer, timespec_to_ktime(*rqtp));
+        hrtimer_set_expires_range_ns(&t.timer, timespec_to_ktime(*rqtp), slack);
         if (do_nanosleep(&t, mode))
                 goto out;