Re: iSER multi-queue configuration

[Ming Lin <mlin@kernel.org>]

On Fri, 2016-04-29 at 14:11 -0700, Ming Lin wrote:
> Hi,
> 
> I use mlx5 to setup iSER and have scsi mq enabled.
> 
> root@xxx:~# cat /sys/module/scsi_mod/parameters/use_blk_mq
> Y
> 
> But it seems there is only 1 HW queue that maps to 48 SW queues.
> 
> root@xxx:/sys/block/sdb/mq# ls
> 0
> 
> root@xxx:/sys/block/sdb/mq# ls 0/
> active  cpu1   cpu11  cpu13  cpu15  cpu17  cpu19  cpu20  cpu22  cpu24
> cpu26  cpu28  cpu3   cpu31  cpu33  cpu35  cpu37  cpu39  cpu40  cpu42
> cpu44  cpu46  cpu5  cpu7  cpu9      dispatched  pending  run
> cpu0    cpu10  cpu12  cpu14  cpu16  cpu18  cpu2   cpu21  cpu23  cpu25
> cpu27  cpu29  cpu30  cpu32  cpu34  cpu36  cpu38  cpu4   cpu41  cpu43
> cpu45  cpu47  cpu6  cpu8  cpu_list  io_poll     queued   tags
> 
> How to configure it that I can have 48 HW queues?
> That is 1 HW queue map to 1 SW queue.

Hi Sagi,

I'm looking at why there is only 1 HW queue for iser.

2185 int scsi_mq_setup_tags(struct Scsi_Host *shost)
2186 {
...
2199         shost->tag_set.nr_hw_queues = shost->nr_hw_queues ? : 1;


It seems because iser code does not set shost->nr_hw_queues at all.

Why?