Re: [PATCH v2 0/6] sched: dynamic: Simplify PREEMPT_DYNAMIC

[Jinjie Ruan]

在 2026/8/7 11:11, Jinjie Ruan 写道:
> 
> 
> 在 2026/8/4 3:17, Mark Rutland 写道:
>> All architectures which currently suppoort PREEMPT_DYNAMIC select
>> ARCH_HAS_PREEMPT_LAZY.  On architectures which select
>> ARCH_HAS_PREEMPT_LAZY, it has not been possible to select the NONE and
>> VOLUNTARY preemption models since v7.0 due to commit:
>>
>>   7dadeaa6e851 ("sched: Further restrict the preemption modes")
>>
>> Hence in practice PREEMPT_DYNAMIC no longer supports the NONE or
>> VOLUNTARY preemption models.
>>
>> This series makes the de-facto situation official by making
>> PREEMPT_DYNAMIC depend on ARCH_HAS_PREEMPT_LAZY, and removing redundant
>> code.
>>
>> Since v1, I've had to rebase atop v7.2-rc4 to avoid a conflict with
>> commit:
>>
>>   a2c02aa0c6ca ("powerpc: Remove dead non-preemption code")
>>
>> Given this is now late in the cycle, and given the tip:sched/core branch
>> is based on v7.2-rc1, I suspect tip folk might not want to queue this
>> now. Please let me know what you'd prefer; I'm happy to rebase and
>> resend after v7.3-rc1.
>>
>> Since v1:
>> * Rebase to v7.2-rc4
>> * Apply Revied-by tags.
>> * Fix typos in commit messages.
>> * Add patch to cleanup accessors (per Shrikanth's comment)
>>
>> Mark.
>>
>> Mark Rutland (6):
>>   sched: dynamic: Make PREEMPT_DYNAMIC depend on ARCH_HAS_PREEMPT_LAZY
>>   sched: dynamic: Simplify {cond,might}_resched()
> 
> 
> Hi Mark,
> 
> We also need to update the Doc.
> 
> --- a/Documentation/admin-guide/kernel-parameters.txt
> +++ b/Documentation/admin-guide/kernel-parameters.txt
> @@ -5410,8 +5410,6 @@ Kernel parameters
> 
>         preempt=        [KNL]
>                         Select preemption mode if you have
> CONFIG_PREEMPT_DYNAMIC
> -                       none - Limited to cond_resched() calls
> -                       voluntary - Limited to cond_resched() and
> might_sleep() calls
>                         full - Any section that isn't explicitly preempt
> disabled
>                                can be preempted anytime.  Tasks will
> also yield
>                                contended spinlocks (if the critical

Hi Mark,

What do you think?


> section isn't
> 
> Best regards,
> Jinjie
> 
>>   sched: dynamic: Simplify preempt_schedule{,_notrace}()
>>   sched: dynamic: Simplify irqentry_exit_cond_resched()
>>   sched: dynamic: Remove HAVE_PREEMPT_DYNAMIC_{CALL,KEY}
>>   sched: dynamic: Simplify preempt model accessors
>>
>>  arch/Kconfig                     |  38 -------
>>  arch/arm64/Kconfig               |   1 -
>>  arch/arm64/include/asm/preempt.h |  10 --
>>  arch/loongarch/Kconfig           |   1 -
>>  arch/powerpc/Kconfig             |   1 -
>>  arch/riscv/Kconfig               |   1 -
>>  arch/s390/Kconfig                |   1 -
>>  arch/s390/include/asm/preempt.h  |  11 --
>>  arch/x86/Kconfig                 |   1 -
>>  arch/x86/include/asm/preempt.h   |  28 -----
>>  include/asm-generic/preempt.h    |  10 --
>>  include/linux/irq-entry-common.h |  17 +--
>>  include/linux/kernel.h           |  20 ----
>>  include/linux/preempt.h          |  20 ++--
>>  include/linux/sched.h            |  31 +-----
>>  kernel/Kconfig.preempt           |   9 +-
>>  kernel/entry/common.c            |  17 +--
>>  kernel/sched/core.c              | 180 +------------------------------
>>  18 files changed, 23 insertions(+), 374 deletions(-)
>>
>