From: Frederic Weisbecker <[email protected]> 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 <[email protected]> Cc: Alessio Igor Bogani <[email protected]> Cc: Andrew Morton <[email protected]> Cc: Avi Kivity <[email protected]> Cc: Chris Metcalf <[email protected]> Cc: Christoph Lameter <[email protected]> Cc: Daniel Lezcano <[email protected]> Cc: Geoff Levand <[email protected]> Cc: Gilad Ben Yossef <[email protected]> Cc: Hakan Akkan <[email protected]> Cc: Ingo Molnar <[email protected]> Cc: Kevin Hilman <[email protected]> Cc: Max Krasnyansky <[email protected]> Cc: Paul E. McKenney <[email protected]> Cc: Peter Zijlstra <[email protected]> Cc: Stephen Hemminger <[email protected]> Cc: Steven Rostedt <[email protected]> Cc: Sven-Thorsten Dietrich <[email protected]> Cc: Thomas Gleixner <[email protected]> --- include/linux/posix-timers.h | 1 + kernel/posix-cpu-timers.c | 12 ++++++++++++ kernel/time/tick-sched.c | 4 ++++ 3 files changed, 17 insertions(+) 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 125cb67..79d4c24 100644 --- a/kernel/posix-cpu-timers.c +++ b/kernel/posix-cpu-timers.c @@ -6,6 +6,7 @@ #include <linux/posix-timers.h> #include <linux/errno.h> #include <linux/math64.h> +#include <linux/cpuset.h> #include <asm/uaccess.h> #include <linux/kernel_stat.h> #include <trace/events/timer.h> @@ -1274,6 +1275,17 @@ 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 de3c8fe..0a5e650 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/cpuset.h> +#include <linux/posix-timers.h> #include <asm/irq_regs.h> @@ -518,6 +519,9 @@ static bool can_stop_adaptive_tick(void) if (!sched_can_stop_tick()) return false; + if (posix_cpu_timers_running(current)) + return false; + /* Is there a grace period to complete ? */ if (rcu_pending(smp_processor_id())) return false; -- 1.7.10.4 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
