Re: [GIT PULL] nohz: Full dynticks base interface

[Frederic Weisbecker]

2013/3/25 Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>:
> On Sun, Mar 24, 2013 at 03:46:40PM +0100, Frederic Weisbecker wrote:
>> 2013/3/24 Ingo Molnar <mingo@xxxxxxxxxx>:
>> >
>> > * Frederic Weisbecker <fweisbec@xxxxxxxxx> wrote:
>> >
>> >> Hi Ingo,
>> >>
>> >> This settles the initial ground to start a special full dynticks tree in -tip
>> >> that we can iterate incrementally to accelerate the development.
>> >> It is based on tip:sched/core.
>> >>
>> >> I tried to rearrange a bit the naming. We are probably not yet done with
>> >> that but I guess we can fix it along with the rest.
>> >>
>> >> Please pull from:
>> >>
>> >> git://git.kernel.org/pub/scm/linux/kernel/git/frederic/linux-dynticks.git
>> >>       full-dynticks-for-mingo
>> >>
>> >> Changes on these commits since they were part of 3.9-rc1-nohz1:
>> >>
>> >> * Force a timekeeping CPU over the full dynticks range
>> >> * Rename CONFIG_NO_HZ_FULL to CONFIG_NO_HZ_EXTENDED
>> >> * Following *_nohz_extended_* APIs renames
>> >> * Handle CPU hotplug for timekeeping
>> >> * Rename full_nohz= kernel parameter to nohz_extended=
>> >
>> > Note that boot parameters suck for pretty much any purpose but quirks -
>> > please also add a (default off!) Kconfig option to easily enable
>> > nohz_extended for all CPUs.
>> >
>> > That way I will be able to test it automatically via randconfig and such.
>>
>> Sure, I'm adding such an option.
>
> Hmmm...  This would be an option to make all but one CPU an adaptive-ticks
> CPU, right?  If so, this leads to the question of whether I should add a
> matching no-CBs Kconfig option.  My guess is "no", because the existing
> CONFIG_RCU_NOCB_CPU_ALL should work just fine -- there would be a CPU that
> was not an adaptive-ticks CPU, but does have its RCU callbacks offloaded.
>
> Or am I missing something here?

No that looks right. Now I wonder if I should select
CONFIG_RCU_NOCB_CPU_ALL at the same time. Probably.
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