From: Kirill A. Shutemov <kirill@xxxxxxxxxxxxx>
task_get_effective_timer_slack() returns timer slack value to be used
to configure per-task timers. It can be equal or higher than task's
timer slack value.
For now task_get_effective_timer_slack() returns timer_slack_ns of the
task. Timer slack cgroup controller will implement a bit more
sophisticated logic.
Signed-off-by: Kirill A. Shutemov <kirill@xxxxxxxxxxxxx>
---
fs/select.c | 7 ++-----
include/linux/sched.h | 6 ++++++
kernel/fork.c | 4 ++++
kernel/futex.c | 4 ++--
kernel/hrtimer.c | 2 +-
5 files changed, 15 insertions(+), 8 deletions(-)
diff --git a/fs/select.c b/fs/select.c
index e56560d..712a122 100644
--- a/fs/select.c
+++ b/fs/select.c
@@ -69,7 +69,6 @@ static long __estimate_accuracy(struct timespec *tv)
long select_estimate_accuracy(struct timespec *tv)
{
- unsigned long ret;
struct timespec now;
/*
@@ -81,10 +80,8 @@ long select_estimate_accuracy(struct timespec *tv)
ktime_get_ts(&now);
now = timespec_sub(*tv, now);
- ret = __estimate_accuracy(&now);
- if (ret < current->timer_slack_ns)
- return current->timer_slack_ns;
- return ret;
+ return clamp_t(long, __estimate_accuracy(&now),
+ task_get_effective_timer_slack(current), LONG_MAX);
}
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 777d8a5..44f6f55 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -2620,6 +2620,12 @@ static inline unsigned long rlimit_max(unsigned int limit)
return task_rlimit_max(current, limit);
}
+static inline unsigned long task_get_effective_timer_slack(
+ struct task_struct *tsk)
+{
+ return tsk->timer_slack_ns;
+}
+
#endif /* __KERNEL__ */
#endif
diff --git a/kernel/fork.c b/kernel/fork.c
index 25e4291..4958de9 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -1089,6 +1089,10 @@ static struct task_struct *copy_process(unsigned long clone_flags,
memset(&p->rss_stat, 0, sizeof(p->rss_stat));
#endif
+ /*
+ * Save current task's (not effective) timer slack value as default
+ * timer slack value for new task.
+ */
p->default_timer_slack_ns = current->timer_slack_ns;
task_io_accounting_init(&p->ioac);
diff --git a/kernel/futex.c b/kernel/futex.c
index b766d28..e5811c4 100644
--- a/kernel/futex.c
+++ b/kernel/futex.c
@@ -1845,7 +1845,7 @@ static int futex_wait(u32 __user *uaddr, unsigned int flags, u32 val,
HRTIMER_MODE_ABS);
hrtimer_init_sleeper(to, current);
hrtimer_set_expires_range_ns(&to->timer, *abs_time,
- current->timer_slack_ns);
+ task_get_effective_timer_slack(current));
}
retry:
@@ -2242,7 +2242,7 @@ static int futex_wait_requeue_pi(u32 __user *uaddr, unsigned int flags,
HRTIMER_MODE_ABS);
hrtimer_init_sleeper(to, current);
hrtimer_set_expires_range_ns(&to->timer, *abs_time,
- current->timer_slack_ns);
+ task_get_effective_timer_slack(current));
}
/*
diff --git a/kernel/hrtimer.c b/kernel/hrtimer.c
index 0c8d7c0..ffc9a8d 100644
--- a/kernel/hrtimer.c
+++ b/kernel/hrtimer.c
@@ -1542,7 +1542,7 @@ long hrtimer_nanosleep(struct timespec *rqtp, struct timespec __user *rmtp,
int ret = 0;
unsigned long slack;
- slack = current->timer_slack_ns;
+ slack = task_get_effective_timer_slack(current);
if (rt_task(current))
slack = 0;
--
1.7.4.1
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