linux-toradex.git/kernel/Kconfig.preempt, branch v5.16-rc6

preempt: Restore preemption model selection configs

2021-11-11T12:09:33+00:00

Commit c597bfddc9e9 ("sched: Provide Kconfig support for default dynamic
preempt mode") changed the selectable config names for the preemption
model. This means a config file must now select

  CONFIG_PREEMPT_BEHAVIOUR=y

rather than

  CONFIG_PREEMPT=y

to get a preemptible kernel. This means all arch config files would need to
be updated - right now they'll all end up with the default
CONFIG_PREEMPT_NONE_BEHAVIOUR.

Rather than touch a good hundred of config files, restore usage of
CONFIG_PREEMPT{_NONE, _VOLUNTARY}. Make them configure:
o The build-time preemption model when !PREEMPT_DYNAMIC
o The default boot-time preemption model when PREEMPT_DYNAMIC

Add siblings of those configs with the _BUILD suffix to unconditionally
designate the build-time preemption model (PREEMPT_DYNAMIC is built with
the "highest" preemption model it supports, aka PREEMPT). Downstream
configs should by now all be depending / selected by CONFIG_PREEMPTION
rather than CONFIG_PREEMPT, so only a few sites need patching up.

Signed-off-by: Valentin Schneider 
Signed-off-by: Peter Zijlstra (Intel) 
Acked-by: Marco Elver 
Link: https://lore.kernel.org/r/20211110202448.4054153-2-valentin.schneider@arm.com

sched: Provide Kconfig support for default dynamic preempt mode

2021-10-05T13:51:56+00:00

Currently the boot defined preempt behaviour (aka dynamic preempt)
selects full preemption by default when the "preempt=" boot parameter
is omitted. However distros may rather want to default to either
no preemption or voluntary preemption.

To provide with this flexibility, make dynamic preemption a visible
Kconfig option and adapt the preemption behaviour selected by the user
to either static or dynamic preemption.

Signed-off-by: Frederic Weisbecker 
Signed-off-by: Peter Zijlstra (Intel) 
Link: https://lkml.kernel.org/r/20210914103134.11309-1-frederic@kernel.org

sched/core: Disable CONFIG_SCHED_CORE by default

2021-06-28T20:43:05+00:00

This option at minimum adds extra code to the scheduler - even if
it's default unused - and most users wouldn't want it.

Reported-by: Linus Torvalds 
Signed-off-by: Ingo Molnar

sched: Add CONFIG_SCHED_CORE help text

2021-06-01T14:00:10+00:00

Hugh noted that the SCHED_CORE Kconfig option could do with a help
text.

Requested-by: Hugh Dickins 
Signed-off-by: Peter Zijlstra (Intel) 
Reviewed-by: Randy Dunlap 
Acked-by: Hugh Dickins 
Link: https://lkml.kernel.org/r/YKyhtwhEgvtUDOyl@hirez.programming.kicks-ass.net

sched: Core-wide rq->lock

2021-05-12T09:43:27+00:00

Introduce the basic infrastructure to have a core wide rq->lock.

This relies on the rq->__lock order being in increasing CPU number
(inside a core). It is also constrained to SMT8 per lockdep (and
SMT256 per preempt_count).

Luckily SMT8 is the max supported SMT count for Linux (Mips, Sparc and
Power are known to have this).

Signed-off-by: Peter Zijlstra (Intel) 
Tested-by: Don Hiatt 
Tested-by: Hongyu Ning 
Tested-by: Vincent Guittot 
Link: https://lkml.kernel.org/r/YJUNfzSgptjX7tG6@hirez.programming.kicks-ass.net

preempt: Introduce CONFIG_PREEMPT_DYNAMIC

2021-02-17T13:12:24+00:00

Preemption mode selection is currently hardcoded on Kconfig choices.
Introduce a dedicated option to tune preemption flavour at boot time,

This will be only available on architectures efficiently supporting
static calls in order not to tempt with the feature against additional
overhead that might be prohibitive or undesirable.

CONFIG_PREEMPT_DYNAMIC is automatically selected by CONFIG_PREEMPT if
the architecture provides the necessary support (CONFIG_STATIC_CALL_INLINE,
CONFIG_GENERIC_ENTRY, and provide with __preempt_schedule_function() /
__preempt_schedule_notrace_function()).

Suggested-by: Peter Zijlstra 
Signed-off-by: Michal Hocko 
Signed-off-by: Frederic Weisbecker 
[peterz: relax requirement to HAVE_STATIC_CALL]
Signed-off-by: Peter Zijlstra (Intel) 
Signed-off-by: Ingo Molnar 
Link: https://lkml.kernel.org/r/20210118141223.123667-5-frederic@kernel.org

sched/Kconfig: Fix spelling mistake in user-visible help text

2019-11-12T10:35:32+00:00

Fix a spelling mistake in the help text for PREEMPT_RT.

Signed-off-by: Srivatsa S. Bhat (VMware) 
Signed-off-by: Thomas Gleixner 
Link: https://lkml.kernel.org/r/157204450499.10518.4542293884417101528.stgit@srivatsa-ubuntu

sched/rt, Kconfig: Unbreak def/oldconfig with CONFIG_PREEMPT=y

2019-07-22T16:05:11+00:00

The merge of the CONFIG_PREEMPT_RT stub renamed CONFIG_PREEMPT to
CONFIG_PREEMPT_LL which causes all defconfigs which have CONFIG_PREEMPT=y
set to fall back to CONFIG_PREEMPT_NONE because CONFIG_PREEMPT depends on
the preemption mode choice wich defaults to NONE. This also affects
oldconfig builds.

So rather than changing 114 defconfig files and being an annoyance to
users, revert the rename and select a new config symbol PREEMPTION. That
keeps everything working smoothly and the revelant ifdef's are going to be
fixed up step by step.

Reported-by: Mark Rutland 
Fixes: a50a3f4b6a31 ("sched/rt, Kconfig: Introduce CONFIG_PREEMPT_RT")
Signed-off-by: Thomas Gleixner

sched/rt, Kconfig: Introduce CONFIG_PREEMPT_RT

2019-07-18T21:10:57+00:00

Add a new entry to the preemption menu which enables the real-time support
for the kernel. The choice is only enabled when an architecture supports
it.

It selects PREEMPT as the RT features depend on it. To achieve that the
existing PREEMPT choice is renamed to PREEMPT_LL which select PREEMPT as
well.

No functional change.

Signed-off-by: Thomas Gleixner 
Acked-by: Paul E. McKenney 
Acked-by: Steven Rostedt (VMware) 
Acked-by: Clark Williams 
Acked-by: Daniel Bristot de Oliveira 
Acked-by: Frederic Weisbecker 
Acked-by: Peter Zijlstra (Intel) 
Acked-by: Marc Zyngier 
Acked-by: Daniel Wagner 
Acked-by: Luis Claudio R. Goncalves 
Acked-by: Julia Cartwright 
Acked-by: Tom Zanussi 
Acked-by: Gratian Crisan 
Acked-by: Sebastian Siewior 
Cc: Andrew Morton 
Cc: Christoph Hellwig 
Cc: Greg Kroah-Hartman 
Cc: Linus Torvalds 
Cc: Lukas Bulwahn 
Cc: Mike Galbraith 
Cc: Tejun Heo 
Link: http://lkml.kernel.org/r/alpine.DEB.2.21.1907172200190.1778@nanos.tec.linutronix.de
Signed-off-by: Ingo Molnar

treewide: Add SPDX license identifier - Makefile/Kconfig

2019-05-21T08:50:46+00:00

Add SPDX license identifiers to all Make/Kconfig files which:

 - Have no license information of any form

These files fall under the project license, GPL v2 only. The resulting SPDX
license identifier is:

  GPL-2.0-only

Signed-off-by: Thomas Gleixner 
Signed-off-by: Greg Kroah-Hartman