On 02/20/16 01:42, Hannes Reinecke wrote:
> ATM the only SCSI driver to support SCSI-mq properly are lpfc, virtio, 
> and fnic. None of the other driver have been modified, and I suspect the 
> performance might be less than stellar.

Hello Hannes,

Before scsi-mq support was added to the above drivers it was added
to the ib_srp driver. Apparently today there are multiple drivers
that support multiple hardware queues:

$ git grep -nH 'nr_hw_queues = [^1]' | grep -vE 'block/blk-mq|scsi/scsi_lib'
drivers/block/null_blk.c:667:           nullb->tag_set.nr_hw_queues = 
submit_queues;
drivers/block/virtio_blk.c:638: vblk->tag_set.nr_hw_queues = vblk->num_vqs;
drivers/block/xen-blkfront.c:927:       info->tag_set.nr_hw_queues = 
info->nr_rings;
drivers/infiniband/ulp/srp/ib_srp.c:3337:       target->scsi_host->nr_hw_queues 
= target->ch_count;
drivers/nvme/host/pci.c:1680:           dev->tagset.nr_hw_queues = 
dev->online_queues - 1;
drivers/scsi/lpfc/lpfc_init.c:3318:     shost->nr_hw_queues = 
phba->cfg_fcp_io_channel;
drivers/scsi/virtio_scsi.c:1008:        shost->nr_hw_queues = num_queues;

Performance data is available in 
http://events.linuxfoundation.org/sites/events/files/slides/Vault%20-%20scsi-mq%20v2.pdf.

Bart.

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