Re: [PATCH v2] sched/rt: Have RT_PUSH_IPI be default off for non PREEMPT_RT

[Shrikanth Hegde <sshegde@linux.ibm.com>]

On 5/18/26 2:17 PM, Valentin Schneider wrote:
> On 15/05/26 10:37, Steven Rostedt wrote:

> I got a bit confused here, please correct me if I didn't get this right:
> 
> Per handle_softirqs(), we can't restart the softirq handling loop if
> need_resched() is true (which would be the case here, per what we'd have
> done it push_rt_task(@pull=true)).
> I thought this meant softirqs couldn't be the issue, however this is only
> valid within the scope of a single handle_softirqs() invocation.
> 
> AIUI here we're being hammered by IRQs, thus under this sort of pattern:
> 
> <IRQ>
>    __irq_exit_rcu()
>      invoke_softirq()
>        handle_softirqs()
>          // handle NET_RX_SOFTIRQ
>          // need_resched() is true so don't loop
> </IRQ>
> 

Wouldn't IRQ exit call schedule if need_resched is set? via irqentry_exit_cond_resched ?

> // Barely any progress made here towards actually executing __schedule()
> 
> <IRQ>
>    __irq_exit_rcu()
>      invoke_softirq()
>        handle_softirqs()
>          // handle NET_RX_SOFTIRQ and wake up some tasks
>          // need_resched() is true so don't loop
> </IRQ>
> 
> & repeat ad nauseam. Did I get this right?
>