Messages in this thread Patch in this message | | | From | Frederic Weisbecker <> | Subject | [PATCH 23/27] nohz: Don't stop the tick if posix cpu timers are running | Date | Sat, 29 Dec 2012 17:43:02 +0100 |
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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 <fweisbec@gmail.com> Cc: Alessio Igor Bogani <abogani@kernel.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Chris Metcalf <cmetcalf@tilera.com> Cc: Christoph Lameter <cl@linux.com> Cc: Geoff Levand <geoff@infradead.org> Cc: Gilad Ben Yossef <gilad@benyossef.com> Cc: Hakan Akkan <hakanakkan@gmail.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Paul Gortmaker <paul.gortmaker@windriver.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Thomas Gleixner <tglx@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 165d476..15f8f4f 100644 --- a/kernel/posix-cpu-timers.c +++ b/kernel/posix-cpu-timers.c @@ -1269,6 +1269,17 @@ 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 04504c4..eb6ad3d 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> @@ -599,6 +600,9 @@ 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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