[SCSI] qla2xxx: Add CPU affinity support.

Set the module parameter ql2xmultique_tag to 1 to enable this
feature. In this mode, the total number of response queues
created is equal to the number of online cpus. Turning the block
layer's rq_affinity mode on enables requests to be routed to the
proper cpu and at the same time it enables completion of the IO
in a response queue that is affined to the cpu in the request
path.

Signed-off-by: Anirban Chakraborty <anirban.chakraborty@qlogic.com>
Signed-off-by: Andrew Vasquez <andrew.vasquez@qlogic.com>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>

1 files changed, 20 insertions, 2 deletions

diff --git a/drivers/scsi/qla2xxx/qla_iocb.c b/drivers/scsi/qla2xxx/qla_iocb.c
index 94b69d86482d..7b15ded991cb 100644
--- a/drivers/scsi/qla2xxx/qla_iocb.c
+++ b/drivers/scsi/qla2xxx/qla_iocb.c
@@ -15,6 +15,7 @@ static request_t *qla2x00_req_pkt(struct scsi_qla_host *, struct req_que *,
                                                         struct rsp_que *rsp);
 static void qla2x00_isp_cmd(struct scsi_qla_host *, struct req_que *);
 
+static void qla25xx_set_que(srb_t *, struct req_que **, struct rsp_que **);
 /**
  * qla2x00_get_cmd_direction() - Determine control_flag data direction.
  * @cmd: SCSI command
@@ -726,8 +727,7 @@ qla24xx_start_scsi(srb_t *sp)
         /* Setup device pointers. */
         ret = 0;
 
-        req = vha->req;
-        rsp = ha->rsp_q_map[0];
+        qla25xx_set_que(sp, &req, &rsp);
         sp->que = req;
 
         /* So we know we haven't pci_map'ed anything yet */
@@ -850,3 +850,21 @@ queuing_error:
 
         return QLA_FUNCTION_FAILED;
 }
+
+static void qla25xx_set_que(srb_t *sp, struct req_que **req,
+        struct rsp_que **rsp)
+{
+        struct scsi_cmnd *cmd = sp->cmd;
+        struct scsi_qla_host *vha = sp->fcport->vha;
+        struct qla_hw_data *ha = sp->fcport->vha->hw;
+        int affinity = cmd->request->cpu;
+
+        if (ql2xmultique_tag && affinity >= 0 &&
+                affinity < ha->max_rsp_queues - 1) {
+                *rsp = ha->rsp_q_map[affinity + 1];
+                *req = ha->req_q_map[1];
+        } else {
+                *req = vha->req;
+                *rsp = ha->rsp_q_map[0];
+        }
+}