lkml.org 
[lkml]   [2013]   [Mar]   [26]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
SubjectRe: [GIT PULL] nohz: Full dynticks base interface
From
2013/3/25 Paul E. McKenney <paulmck@linux.vnet.ibm.com>:
> On Mon, Mar 25, 2013 at 06:12:12PM +0100, Frederic Weisbecker wrote:
>> 2013/3/25 Paul E. McKenney <paulmck@linux.vnet.ibm.com>:
>> > On Sun, Mar 24, 2013 at 03:46:40PM +0100, Frederic Weisbecker wrote:
>> >> 2013/3/24 Ingo Molnar <mingo@kernel.org>:
>> >> >
>> >> > * Frederic Weisbecker <fweisbec@gmail.com> 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.
>
> Sounds like a good initial position to me. If it somehow causes problems,
> we can always change it later.

Ah "rcu: Provide compile-time control for no-CBs CPUs" is not yet in
-tip so I can't do that yet. Ok for now I'm going to add
CONFIG_NO_HZ_EXTENDED_ALL and will select the matching RCU config once
it's visible upstream.


\
 
 \ /
  Last update: 2013-03-27 04:21    [W:0.096 / U:0.048 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site