Hi Ming On 07/31/2018 12:58 PM, Ming Lei wrote: > 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() > > Oh, sorry, I didn't look into this patch due to its title when iterated the mail list, therefore I didn't realize the RR restart loop has already been killed. :) The RR restart loop could ensure the fairness of sharing some LLDD resource, not just avoid IO hung. Is it OK to kill it totally ? Thanks Jianchao
