Re: [PATCH RFC] blk-mq: Don't IPI requests on PREEMPT_RT

The remaining part is a switch to llist which avoids locking (IRQ
off/on) and it allows invoke the IPI/raise softirq only if something was
added. The entries are now processed in the reverse order but this
shouldn't matter right?

For correctness it should not matter, but I think it could have
performance implications.  I think you'll have to throw in a
llist_reverse_order.

I would split this into two patches (the blk_mq_complete_need_ipi() hunk
and the llist part) unless there are objections.

Yes, please do.