Re: [RFC] blk-mq: clean up the hctx restart

[Ming Lei]

On Tue, Jul 31, 2018 at 12:02:15PM +0800, Jianchao Wang wrote:
> Currently, we will always set SCHED_RESTART whenever there are
> requests in hctx->dispatch, then when request is completed and
> freed the hctx queues will be restarted to avoid IO hang. This
> is unnecessary most of time. Especially when there are lots of
> LUNs attached to one host, the RR restart loop could be very
> expensive.

The big RR restart loop has been killed in the following commit:

commit 97889f9ac24f8d2fc8e703ea7f80c162bab10d4d
Author: Ming Lei <ming.lei@xxxxxxxxxx>
Date:   Mon Jun 25 19:31:48 2018 +0800

    blk-mq: remove synchronize_rcu() from blk_mq_del_queue_tag_set()


Thanks,
Ming