If either a per thread or a per process posix cpu timer is running,
don't stop the tick.
TODO: restart the tick if it is stopped and a posix cpu timer is
enqueued. Check we probably need a memory barrier for the per
process posix timer that can be enqueued from another task
of the group.
Signed-off-by: Frederic Weisbecker <fweis...@gmail.com>
Cc: Alessio Igor Bogani <abog...@kernel.org>
Cc: Andrew Morton <a...@linux-foundation.org>
Cc: Avi Kivity <a...@redhat.com>
Cc: Chris Metcalf <cmetc...@tilera.com>
Cc: Christoph Lameter <c...@linux.com>
Cc: Geoff Levand <ge...@infradead.org>
Cc: Gilad Ben Yossef <gi...@benyossef.com>
Cc: Hakan Akkan <hakanak...@gmail.com>
Cc: Ingo Molnar <mi...@kernel.org>
Cc: Paul E. McKenney <paul...@linux.vnet.ibm.com>
Cc: Paul Gortmaker <paul.gortma...@windriver.com>
Cc: Peter Zijlstra <pet...@infradead.org>
Cc: Steven Rostedt <rost...@goodmis.org>
Cc: Thomas Gleixner <t...@linutronix.de>
---
include/linux/posix-timers.h | 1 +
kernel/posix-cpu-timers.c | 11 +++++++++++
kernel/time/tick-sched.c | 4 ++++
3 files changed, 16 insertions(+), 0 deletions(-)
diff --git a/include/linux/posix-timers.h b/include/linux/posix-timers.h
index 042058f..97480c2 100644
--- a/include/linux/posix-timers.h
+++ b/include/linux/posix-timers.h
@@ -119,6 +119,7 @@ int posix_timer_event(struct k_itimer *timr, int
si_private);
void posix_cpu_timer_schedule(struct k_itimer *timer);
void run_posix_cpu_timers(struct task_struct *task);
+bool posix_cpu_timers_running(struct task_struct *tsk);
void posix_cpu_timers_exit(struct task_struct *task);
void posix_cpu_timers_exit_group(struct task_struct *task);
diff --git a/kernel/posix-cpu-timers.c b/kernel/posix-cpu-timers.c
index 3d58bd5..d3b46b3 100644
--- a/kernel/posix-cpu-timers.c
+++ b/kernel/posix-cpu-timers.c
@@ -1266,6 +1266,17 @@ static inline int fastpath_timer_check(struct
task_struct *tsk)
return 0;
}
+bool posix_cpu_timers_running(struct task_struct *tsk)
+{
+ if (!task_cputime_zero(&tsk->cputime_expires))
+ return true;
+
+ if (tsk->signal->cputimer.running)
+ return true;
+
+ return false;
+}
+
/*
* This is called from the timer interrupt handler. The irq handler has
* already updated our counts. We need to check if any timers fire now.
diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c
index 0c9281a..4f4fa13 100644
--- a/kernel/time/tick-sched.c
+++ b/kernel/time/tick-sched.c
@@ -21,6 +21,7 @@
#include <linux/sched.h>
#include <linux/module.h>
#include <linux/irq_work.h>
+#include <linux/posix-timers.h>
#include <asm/irq_regs.h>
@@ -597,6 +598,9 @@ static bool can_stop_full_tick(int cpu)
if (rcu_pending(cpu))
return false;
+ if (posix_cpu_timers_running(current))
+ return false;
+
return true;
}
#endif
--
1.7.5.4
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