On Wed, 2018-08-01 at 16:58 +0800, Ming Lei wrote:

On Wed, Aug 01, 2018 at 10:17:30AM +0800, jianchao.wang wrote:

quoted

However, due to the limits in hctx_may_queue, q_b s=

till cannot get the

quoted

tags. The RR restart also will not wake up q_a.
This is unfair for q_a.
=20
When we remove RR restart fashion, at least, the q_a will b=

e waked up by

quoted

the hctx restart.
Is this the improvement of fairness you said in driver tag allo=

cation ?

=20
I mean the fairness is totally covered by the general tag allocation
algorithm now, which is sort of FIFO style because of waitqueue, but =

RR

restart wakes up queue in the order of request queue.

From sbitmap.h:

#define SBQ_WAIT_QUEUES 8

What do you think is the effect of your patch if more than eight LUNs are
active and the SCSI queue is full?

Thanks,

Bart.