Re: [PATCH 2/4 v2] nohz: Split extended quiescent state handling from nohz switch

Chris Metcalf
2011-06-06T20:30:04Z

On 6/5/2011 11:20 PM, Frederic Weisbecker wrote:
> It is assumed that rcu won't be used once we switch to tickless
> mode and until we restart the tick. However this is not always
> true, as in x86-64 where we dereference the idle notifiers after
> the tick is stopped.
>
> To prepare for fixing this, split the tickless mode switching and
> RCU extended quiescent state logics.
> Make tick_nohz_stop/restart_sched_tick() RCU agnostic but provide
> a new pair of APIs tick_nohz_enter/exit_idle() that keep the
> old behaviour by handling both the nohz mode and RCU extended
> quiescent states, then convert every archs to use these.
>
> Archs that want to switch to extended QS to some custom points
> can do it later by using tick_nohz_stop_sched_tick() and
> rcu_enter_nohz() seperately.
>
> v2: Remove rcu_exit_nohz() from tick_nohz_restart_sched_tick()
>
> [...]
> arch/tile/kernel/process.c | 4 +-

Acked-by: Chris Metcalf <cmetcalf@tilera.com>

--
Chris Metcalf, Tilera Corp.