[PATCH V8 0/4] blk-mq: implement queue quiesce via percpu_ref for BLK_MQ_F_BLOCKING

[Sagi Grimberg]

> About nvme_stop_queues need long times for large number namespaces,
> If work with multipath and one path fails, It cause wait long times
> to fail over to retry, and the more namespaces the longer the time.
> This has a great impact on delay-sensitive services.
> there are two options to fix it:
> 1. Use percpu instead of SRCU. Ming's patchset.
> 2. Use tagset quiesce interface with SRCU. Sagi's patchset.
> The two patchsets are still pending.
> 
> It is a serious bug, I expect that we can revisit the solution.
> Maybe we don't have the best option, but we need to choose a relatively
> acceptable option.
> 
> Can we fix the bug for non-blocking queues(which used by fc&rdma) first?
> 
> Sagi & Ming, what do you think?

I don't recall any outstanding concerns that I had (I think they
were all addressed). I'm fine with moving forward with it.