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SubjectRe: [Query] Can we use normal timers (kernel/timer.c) while in NO_HZ_FULL mode?
On Wed, Jun 04, 2014 at 07:14:43PM +0530, Viresh Kumar wrote:
> On 4 June 2014 18:53, Frederic Weisbecker <fweisbec@gmail.com> wrote:
> > Right, if we enqueue a timer when the tick is stopped, we call wake_up_nohz_cpu().
>
> Ahh, I looked at __mod_timer() :)
>
> BTW, shouldn't we do something similar for mod_timer_pinned()
> as well ?

Ah that looks right. In fact we should probably move the wake_up_nohz_cpu()
to internal_add_timer().

And that concerns nohz idle as well. If mod_timer() selects a CPU that doesn't
appear to be idle in get_nohz_timer_target() but then becomes idle afterward
before we lock its timer base, the CPU may well miss the timer.


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