On 2022-07-12 01:23:15 [+0800], Schspa Shi wrote:
> I want to know if this difference is by design.
Yes. type1 (LAZY) does not need immediate action but can't be scheduled
regularly like a workqueue.
> If this is by design, we have a problem that the irq_work of type2
> will not execute as quickly as expected, it may be delayed by the
> irq_work of type1.
>
> Please consider the following scenarios:
>
> If the CPU queued a type1 irq_work A, and then a type2 irq_work B.
> But we won't make B executed quickly, because we won't issue the IPI
> interrupt to wakeup irq_workd (the llist_add call will return false).
But those two are different lists. So adding type1 to list1 does not
affect type2 with list2
> This PATCH will issue the IPI_IRQ_WORK to make B execute quickly.
>
> One thing that needs to be optimized is that we now have
> lazy_list.node.llist and lazy_work_raised which need to be granted
> to be atomicity, disabled the local CPU IRQ to make this atomic.
> There should be a better way to make these two variants to be atomically
> and I can go in deep if this little problem is not by design, and need
> to be fixed.
>
> If these two types of irq_work should be the same with the priority.
> maybe we should change.
>
> if (!lazy_work || tick_nohz_tick_stopped()) {
> arch_irq_work_raise();
> }
>
> to
>
> if (!(lazy_work || rt_lazy_work) || tick_nohz_tick_stopped()) {
> arch_irq_work_raise();
> }
but we wait for the timer for the lazy-work. RT has more LAZY items
compared to !RT. So if there is an error then it should be visible
there, too.
Is there a problem with this? Adding (as you call it) type1 item does
not affect type2 items. They will will processed asap.
Sebastian
