scsi: lpfc: reduce locking when updating statistics (18027a8c) · Commits · 戴 / test

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>

drivers/scsi/lpfc/lpfc_scsi.c

+10 −8

Original line number	Diff line number	Diff line
		@@ -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;
		@@ -211,15 +211,17 @@ 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 \|\|
		if (!pnode \|\|
		!pnode->lat_data \|\|
		(phba->bucket_type == LPFC_NO_BUCKET)) {
		spin_unlock_irqrestore(shost->host_lock, flags);

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