Re: [RFC PATCH 3/3] softirq: Avoid waking up ksoftirqd from flush_smp_call_function_queue()

[K Prateek Nayak]

Hello Peter,

Thank you for the feedback.

On 7/10/2024 8:35 PM, Peter Zijlstra wrote:
> On Wed, Jul 10, 2024 at 09:02:10AM +0000, K Prateek Nayak wrote:
>
> > [..snip..]
>
> On first reading I wonder why you've not re-used and hooked into the
> PREEMPT_RT variant of should_wake_ksoftirqd(). That already has a per
> CPU variable to do exactly this.

With this RFC, I intended to check if everyone was onboard with the idea
and of the use-case. One caveat with re-using the existing
"softirq_ctrl.cnt" hook that PREEMPT_RT uses is that we'll need to
expose the functions that increment and decrement it, for it to be used
in kernel/smp.c. I'll make those changes in v2 and we can see if there
are sufficient WARN_ON() to catch any incorrect usage in !PREEMPT_RT
case.

--
Thanks and Regards,
Prateek