scsi: lpfc: Allow override of hardware queue selection policies

Default behavior is to use the information from the upper IO stacks to
select the hardware queue to use for IO submission.  Which typically has
good cpu affinity.

However, the driver, when used on some variants of the upstream kernel, has
found queuing information to be suboptimal for FCP or IO completion locked
on particular cpus.

For command submission situations, the lpfc_fcp_io_sched module parameter
can be set to specify a hardware queue selection policy that overrides the
os stack information.

For IO completion situations, rather than queing cq processing based on the
cpu servicing the interrupting event, schedule the cq processing on the cpu
associated with the hardware queue's cq.

Signed-off-by: Dick Kennedy <dick.kennedy@broadcom.com>
Signed-off-by: James Smart <jsmart2021@gmail.com>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

1 files changed, 11 insertions, 3 deletions

diff --git a/drivers/scsi/lpfc/lpfc_nvme.c b/drivers/scsi/lpfc/lpfc_nvme.c
index 0c6c91d39e2f..c9aacd56a449 100644
--- a/drivers/scsi/lpfc/lpfc_nvme.c
+++ b/drivers/scsi/lpfc/lpfc_nvme.c
@@ -1546,8 +1546,17 @@ lpfc_nvme_fcp_io_submit(struct nvme_fc_local_port *pnvme_lport,
 		}
 	}
 
-	lpfc_ncmd = lpfc_get_nvme_buf(phba, ndlp,
-				      lpfc_queue_info->index, expedite);
+	if (phba->cfg_fcp_io_sched == LPFC_FCP_SCHED_BY_HDWQ) {
+		idx = lpfc_queue_info->index;
+	} else {
+		cpu = smp_processor_id();
+		if (cpu < phba->cfg_hdw_queue)
+			idx = cpu;
+		else
+			idx = cpu % phba->cfg_hdw_queue;
+	}
+
+	lpfc_ncmd = lpfc_get_nvme_buf(phba, ndlp, idx, expedite);
 	if (lpfc_ncmd == NULL) {
 		atomic_inc(&lport->xmt_fcp_noxri);
 		lpfc_printf_vlog(vport, KERN_INFO, LOG_NVME_IOERR,
@@ -1585,7 +1594,6 @@ lpfc_nvme_fcp_io_submit(struct nvme_fc_local_port *pnvme_lport,
 	 * index to use and that they have affinitized a CPU to this hardware
 	 * queue. A hardware queue maps to a driver MSI-X vector/EQ/CQ/WQ.
 	 */
-	idx = lpfc_queue_info->index;
 	lpfc_ncmd->cur_iocbq.hba_wqidx = idx;
 	cstat = &phba->sli4_hba.hdwq[idx].nvme_cstat;