Messages in this thread Patch in this message | | | Date | Thu, 19 Nov 2015 20:59:05 +0100 | From | Peter Zijlstra <> | Subject | Re: [PATCH 2/4] timer: relax tick stop in idle entry |
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On Thu, Nov 19, 2015 at 11:21:25AM -0800, Jacob Pan wrote: > On Thu, 19 Nov 2015 20:06:30 +0100 > Peter Zijlstra <peterz@infradead.org> wrote: > > > Which one? That is, I cannot find a idle_cpu() call from > > tick_nohz_irq_exit(). > it is tick_irq_exit(void), i will not call tick_nohz_irq_exit() if > !idle_cpu()
Ah, but I think we really only need to test for the idle task there, the && need_resched() part of that function takes care of the rest.
Once we have need_resched() set, we'll be on our way to tick_nohz_idle_exit() to restart the tick again.
--- kernel/softirq.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/kernel/softirq.c b/kernel/softirq.c index 479e4436f787..3bd30404f2ee 100644 --- a/kernel/softirq.c +++ b/kernel/softirq.c @@ -367,7 +367,7 @@ static inline void tick_irq_exit(void) int cpu = smp_processor_id(); /* Make sure that timer wheel updates are propagated */ - if ((idle_cpu(cpu) && !need_resched()) || tick_nohz_full_cpu(cpu)) { + if ((is_idle_task(current) && !need_resched()) || tick_nohz_full_cpu(cpu)) { if (!in_interrupt()) tick_nohz_irq_exit(); }
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