On 12/2/20 11:27 AM, Tyrel Datwyler wrote: > On 12/2/20 7:14 AM, Brian King wrote: >> On 12/1/20 6:53 PM, Tyrel Datwyler wrote: >>> Introduce several new vhost fields for managing MQ state of the adapter >>> as well as initial defaults for MQ enablement. >>> >>> Signed-off-by: Tyrel Datwyler <tyreld@xxxxxxxxxxxxx> >>> --- >>> drivers/scsi/ibmvscsi/ibmvfc.c | 9 ++++++++- >>> drivers/scsi/ibmvscsi/ibmvfc.h | 13 +++++++++++-- >>> 2 files changed, 19 insertions(+), 3 deletions(-) >>> >>> diff --git a/drivers/scsi/ibmvscsi/ibmvfc.c b/drivers/scsi/ibmvscsi/ibmvfc.c >>> index 42e4d35e0d35..f1d677a7423d 100644 >>> --- a/drivers/scsi/ibmvscsi/ibmvfc.c >>> +++ b/drivers/scsi/ibmvscsi/ibmvfc.c >>> @@ -5161,12 +5161,13 @@ static int ibmvfc_probe(struct vio_dev *vdev, const struct vio_device_id *id) >>> } >>> >>> shost->transportt = ibmvfc_transport_template; >>> - shost->can_queue = max_requests; >>> + shost->can_queue = (max_requests / IBMVFC_SCSI_HW_QUEUES); >> >> This doesn't look right. can_queue is the SCSI host queue depth, not the MQ queue depth. > > Our max_requests is the total number commands allowed across all queues. From > what I understand is can_queue is the total number of commands in flight allowed > for each hw queue. > > /* > * In scsi-mq mode, the number of hardware queues supported by the LLD. > * > * Note: it is assumed that each hardware queue has a queue depth of > * can_queue. In other words, the total queue depth per host > * is nr_hw_queues * can_queue. However, for when host_tagset is set, > * the total queue depth is can_queue. > */ > > We currently don't use the host wide shared tagset. Ok. I missed that bit... In that case, since we allocate by default only 100 event structs. If we slice that across IBMVFC_SCSI_HW_QUEUES (16) queues, then we end up with only about 6 commands that can be outstanding per queue, which is going to really hurt performance... I'd suggest bumping up IBMVFC_MAX_REQUESTS_DEFAULT from 100 to 1000 as a starting point. Thanks, Brian -- Brian King Power Linux I/O IBM Linux Technology Center
