[dm-devel] dm-multipath test scripts
Bart Van Assche
bart.vanassche at sandisk.com
Sat Feb 20 15:13:07 UTC 2016
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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