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scsi: lpfc: reduce locking when updating statistics 

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>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
This commit is contained in:
James Smart 2018-09-10 10:30:49 -07:00 committed by Martin K. Petersen
parent 2879265f51
commit 18027a8ccc
1 changed files with 10 additions and 8 deletions
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18
drivers/scsi/lpfc/lpfc_scsi.c
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@ -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;
}