Messages in this thread Patch in this message | | | From | Frederic Weisbecker <> | Subject | [RFC PATCH 6/8] irq_work: Handle queuing without IPI support in dyntick idle mode | Date | Sat, 20 Oct 2012 12:22:45 -0400 |
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If we enqueue a work while in dyntick idle mode and the arch doesn't have self-IPI support, we may not find an opportunity to run the work before a while.
In this case, exit the idle loop to re-evaluate irq_work_needs_cpu() and restart the tick.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@kernel.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Paul Gortmaker <paul.gortmaker@windriver.com> --- kernel/irq_work.c | 11 +++++++++++ 1 files changed, 11 insertions(+), 0 deletions(-)
diff --git a/kernel/irq_work.c b/kernel/irq_work.c index 19f537b..f3bdcf4 100644 --- a/kernel/irq_work.c +++ b/kernel/irq_work.c @@ -71,6 +71,17 @@ static void __irq_work_queue(struct irq_work *work, bool ipi) */ if (ipi || !arch_irq_work_has_ipi() || tick_nohz_tick_stopped()) arch_irq_work_raise(); + + /* + * If we rely on the timer tick or some obscure way to run the work + * while the CPU is in dyntick idle mode, we may not have an opportunity + * to do so before a while. Let's just exit the idle loop and hope we + * haven't yet reached the last need_resched() check before the CPU goes + * to low power mode. + */ + if (!arch_irq_work_has_ipi() && tick_nohz_tick_stopped() + && is_idle_task(current)) + set_need_resched(); } preempt_enable(); } -- 1.7.5.4
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