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

Hans-Christian Egtvedt
2011-06-06T15:18:14Z

On Mon, 2011-06-06 at 05:20 +0200, 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()
>
> Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
> Cc: Ingo Molnar <mingo@elte.hu>
> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
> Cc: Thomas Gleixner <tglx@linutronix.de>
> Cc: H. Peter Anvin <hpa@zytor.com>
> Cc: Russell King <linux@arm.linux.org.uk>
> Cc: Hans-Christian Egtvedt <hans-christian.egtvedt@atmel.com>
> Cc: Mike Frysinger <vapier@gentoo.org>
> Cc: Ralf Baechle <ralf@linux-mips.org>
> Cc: Paul Mackerras <paulus@samba.org>
> Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
> Cc: Paul Mundt <lethal@linux-sh.org>
> Cc: David Miller <davem@davemloft.net>
> Cc: Chris Metcalf <cmetcalf@tilera.com>
> Cc: Guan Xuetao <gxt@mprc.pku.edu.cn>

<snipp>

> arch/avr32/kernel/process.c | 4 +-

For the AVR32 related bits

Acked-by: Hans-Christian Egtvedt <hans-christian.egtvedt@atmel.com>

<snipp>

--
Hans-Christian Egtvedt