Commit-ID: 555347f6c080d2f25265f981c963605b4dd3610d
Gitweb: http://git.kernel.org/tip/555347f6c080d2f25265f981c963605b4dd3610d
Author: Frederic Weisbecker <fweisbec@xxxxxxxxx>
AuthorDate: Fri, 19 Apr 2013 16:17:38 +0200
Committer: Frederic Weisbecker <fweisbec@xxxxxxxxx>
CommitDate: Fri, 19 Apr 2013 16:31:40 +0200
posix_timers: New API to prevent from stopping the tick when timers are running
Bring a new helper that the full dynticks infrastructure can
call in order to know if it can safely stop the tick from
the posix cpu timers subsystem point of view.
Signed-off-by: Frederic Weisbecker <fweisbec@xxxxxxxxx>
Cc: Chris Metcalf <cmetcalf@xxxxxxxxxx>
Cc: Christoph Lameter <cl@xxxxxxxxx>
Cc: Geoff Levand <geoff@xxxxxxxxxxxxx>
Cc: Gilad Ben Yossef <gilad@xxxxxxxxxxxxx>
Cc: Hakan Akkan <hakanakkan@xxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Kevin Hilman <khilman@xxxxxxxxxx>
Cc: Li Zhong <zhong@xxxxxxxxxxxxxxxxxx>
Cc: Oleg Nesterov <oleg@xxxxxxxxxx>
Cc: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
Cc: Paul Gortmaker <paul.gortmaker@xxxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Steven Rostedt <rostedt@xxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
---
include/linux/posix-timers.h | 2 ++
kernel/posix-cpu-timers.c | 41 ++++++++++++++++++++++++++---------------
2 files changed, 28 insertions(+), 15 deletions(-)
diff --git a/include/linux/posix-timers.h b/include/linux/posix-timers.h
index 042058f..3698d9d 100644
--- a/include/linux/posix-timers.h
+++ b/include/linux/posix-timers.h
@@ -122,6 +122,8 @@ void run_posix_cpu_timers(struct task_struct *task);
void posix_cpu_timers_exit(struct task_struct *task);
void posix_cpu_timers_exit_group(struct task_struct *task);
+bool posix_cpu_timers_can_stop_tick(struct task_struct *tsk);
+
void set_process_cpu_timer(struct task_struct *task, unsigned int clock_idx,
cputime_t *newval, cputime_t *oldval);
diff --git a/kernel/posix-cpu-timers.c b/kernel/posix-cpu-timers.c
index 0bc3356..84d5cb3 100644
--- a/kernel/posix-cpu-timers.c
+++ b/kernel/posix-cpu-timers.c
@@ -155,6 +155,21 @@ static void bump_cpu_timer(struct k_itimer *timer,
}
}
+/**
+ * task_cputime_zero - Check a task_cputime struct for all zero fields.
+ *
+ * @cputime: The struct to compare.
+ *
+ * Checks @cputime to see if all fields are zero. Returns true if all fields
+ * are zero, false if any field is nonzero.
+ */
+static inline int task_cputime_zero(const struct task_cputime *cputime)
+{
+ if (!cputime->utime && !cputime->stime && !cputime->sum_exec_runtime)
+ return 1;
+ return 0;
+}
+
static inline cputime_t prof_ticks(struct task_struct *p)
{
cputime_t utime, stime;
@@ -654,6 +669,17 @@ static void posix_cpu_timer_kick_nohz(void)
{
schedule_work(&nohz_kick_work);
}
+
+bool posix_cpu_timers_can_stop_tick(struct task_struct *tsk)
+{
+ if (!task_cputime_zero(&tsk->cputime_expires))
+ return true;
+
+ if (tsk->signal->cputimer.running)
+ return true;
+
+ return false;
+}
#else
static inline void posix_cpu_timer_kick_nohz(void) { }
#endif
@@ -1032,21 +1058,6 @@ static void check_cpu_itimer(struct task_struct *tsk, struct cpu_itimer *it,
}
}
-/**
- * task_cputime_zero - Check a task_cputime struct for all zero fields.
- *
- * @cputime: The struct to compare.
- *
- * Checks @cputime to see if all fields are zero. Returns true if all fields
- * are zero, false if any field is nonzero.
- */
-static inline int task_cputime_zero(const struct task_cputime *cputime)
-{
- if (!cputime->utime && !cputime->stime && !cputime->sum_exec_runtime)
- return 1;
- return 0;
-}
-
/*
* Check for any per-thread CPU timers that have fired and move them
* off the tsk->*_timers list onto the firing list. Per-thread timers
--
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