Re: [PATCH 2/7] rcu: limit PREEMPT_RCU configurations

[Ankur Arora]

Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx> writes:

> On 2024-10-10 10:35:25 [-0700], Ankur Arora wrote:
>> That's odd. I have that exact configuration (PREEMPT_DYANMIC=n,
>> PREEMPT_LAZY=y, PREEMPT_RCU=n).
>>
>> Can you share your .config?
>
> Sent offlist.

Thanks. So, I tried the config and your config enables
PREEMPT_LAZY=y, PREEMPT_DYNAMIC=n.

That forces PREEMPT_RCU=n.

If in that config you change the preemption options to
PREEMPT_LAZY=y, PREEMPT_DYNAMIC=y, we get PREEMPT_RCU=y.

Is that also the behaviour you are seeing? Seems to be doing
the right thing.

Also, quite similar to how we handle the PREEMPT_NONE/_VOLUNTARY
case. And, lazy is meant to have similar preemption behaviour
as those models.

--
ankur