On 11/10/2018 07:36, Christoph Hellwig wrote:
On Wed, Oct 10, 2018 at 09:58:25PM -0400, Martin K. Petersen wrote:
This is because the IPTT index must be a unique value per HBA. However,
if we switched to SCSI MQ, the block layer tag becomes unique per queue,
and not per HBA.
That doesn't sound right.
Hmmm, well this is what I was told ...
blk-mq tags are always per-host (which has actually caused problems for
ATA, which is now using its own per-device tags).
So, for example, if Scsi_host.can_queue = 2048 and
Scsi_host.nr_hw_queues = 16, then rq tags are still in range [0, 2048)
for that HBA, i.e. invariant on queue count?
.
Thanks,
John
