diff mbox series

[09/11] lpfc: reduce locking when updating statistics

Message ID 20180910173051.6272-10-jsmart2021@gmail.com (mailing list archive)
State Accepted
Headers show
Series lpfc updates for 12.0.0.7 | expand

Commit Message

James Smart Sept. 10, 2018, 5:30 p.m. UTC 
Currently, on each io completion, the stats update routine
indiscriminately holds a lock. While holding the adapter-wide lock,
checks are made to check whether status are being tracked. When
disabled (the default), the locking wasted a lot of cycles.

Check for stats enablement before taking the lock.

Signed-off-by: Dick Kennedy <dick.kennedy@broadcom.com>
Signed-off-by: James Smart <james.smart@broadcom.com>
---
 drivers/scsi/lpfc/lpfc_scsi.c | 18 ++++++++++--------
 1 file changed, 10 insertions(+), 8 deletions(-)
diff mbox series

Patch

diff --git a/drivers/scsi/lpfc/lpfc_scsi.c b/drivers/scsi/lpfc/lpfc_scsi.c
index 200b5bca1f5f..f2d5420be413 100644
--- a/drivers/scsi/lpfc/lpfc_scsi.c
+++ b/drivers/scsi/lpfc/lpfc_scsi.c
@@ -202,8 +202,8 @@  lpfc_sli4_set_rsp_sgl_last(struct lpfc_hba *phba,
 static void
 lpfc_update_stats(struct lpfc_hba *phba, struct  lpfc_scsi_buf *lpfc_cmd)
 {
-	struct lpfc_rport_data *rdata = lpfc_cmd->rdata;
-	struct lpfc_nodelist *pnode = rdata->pnode;
+	struct lpfc_rport_data *rdata;
+	struct lpfc_nodelist *pnode;
 	struct scsi_cmnd *cmd = lpfc_cmd->pCmd;
 	unsigned long flags;
 	struct Scsi_Host  *shost = cmd->device->host;
@@ -211,17 +211,19 @@  lpfc_update_stats(struct lpfc_hba *phba, struct  lpfc_scsi_buf *lpfc_cmd)
 	unsigned long latency;
 	int i;
 
-	if (cmd->result)
+	if (!vport->stat_data_enabled ||
+	    vport->stat_data_blocked ||
+	    (cmd->result))
 		return;
 
 	latency = jiffies_to_msecs((long)jiffies - (long)lpfc_cmd->start_time);
+	rdata = lpfc_cmd->rdata;
+	pnode = rdata->pnode;
 
 	spin_lock_irqsave(shost->host_lock, flags);
-	if (!vport->stat_data_enabled ||
-		vport->stat_data_blocked ||
-		!pnode ||
-		!pnode->lat_data ||
-		(phba->bucket_type == LPFC_NO_BUCKET)) {
+	if (!pnode ||
+	    !pnode->lat_data ||
+	    (phba->bucket_type == LPFC_NO_BUCKET)) {
 		spin_unlock_irqrestore(shost->host_lock, flags);
 		return;
 	}