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@xxxxxxxxxxxx>
Signed-off-by: James Smart <james.smart@xxxxxxxxxxxx>
---
drivers/scsi/lpfc/lpfc_scsi.c | 18 ++++++++++--------
1 file changed, 10 insertions(+), 8 deletions(-)
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;
}
--
2.13.1
