scsi: lpfc: Make ktime sampling more accurate

Need to make ktime samples more accurate

If ktime is turned on in the middle of an IO, the max calculation could
be misleading. Base sampling on the start time of the IO as opposed to
ktime_on.

Make ISR ktime timestamps be from when CQE is read instead of EQE.
Added additional sanity checks when deciding whether to accept an IO
sample or not.

Signed-off-by: Dick Kennedy <dick.kennedy@broadcom.com>
Signed-off-by: James Smart <james.smart@broadcom.com>
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

1 files changed, 66 insertions, 33 deletions

diff --git a/drivers/scsi/lpfc/lpfc_nvmet.c b/drivers/scsi/lpfc/lpfc_nvmet.c
index 313d5c10e0ad..46b411894964 100644
--- a/drivers/scsi/lpfc/lpfc_nvmet.c
+++ b/drivers/scsi/lpfc/lpfc_nvmet.c
@@ -221,9 +221,8 @@ lpfc_nvmet_ctxbuf_post(struct lpfc_hba *phba, struct lpfc_nvmet_ctxbuf *ctx_buf)
 		spin_lock_init(&ctxp->ctxlock);
 
 #ifdef CONFIG_SCSI_LPFC_DEBUG_FS
-		if (phba->ktime_on) {
+		if (ctxp->ts_cmd_nvme) {
 			ctxp->ts_cmd_nvme = ktime_get_ns();
-			ctxp->ts_isr_cmd = ctxp->ts_cmd_nvme;
 			ctxp->ts_nvme_data = 0;
 			ctxp->ts_data_wqput = 0;
 			ctxp->ts_isr_data = 0;
@@ -289,9 +288,7 @@ lpfc_nvmet_ktime(struct lpfc_hba *phba,
 {
 	uint64_t seg1, seg2, seg3, seg4, seg5;
 	uint64_t seg6, seg7, seg8, seg9, seg10;
-
-	if (!phba->ktime_on)
-		return;
+	uint64_t segsum;
 
 	if (!ctxp->ts_isr_cmd || !ctxp->ts_cmd_nvme ||
 	    !ctxp->ts_nvme_data || !ctxp->ts_data_wqput ||
@@ -300,6 +297,8 @@ lpfc_nvmet_ktime(struct lpfc_hba *phba,
 	    !ctxp->ts_isr_status || !ctxp->ts_status_nvme)
 		return;
 
+	if (ctxp->ts_status_nvme < ctxp->ts_isr_cmd)
+		return;
 	if (ctxp->ts_isr_cmd  > ctxp->ts_cmd_nvme)
 		return;
 	if (ctxp->ts_cmd_nvme > ctxp->ts_nvme_data)
@@ -344,34 +343,66 @@ lpfc_nvmet_ktime(struct lpfc_hba *phba,
 	 * (Segments 1 thru 4) for READDATA_RSP
 	 */
 	seg1 = ctxp->ts_cmd_nvme - ctxp->ts_isr_cmd;
-	seg2 = (ctxp->ts_nvme_data - ctxp->ts_isr_cmd) - seg1;
-	seg3 = (ctxp->ts_data_wqput - ctxp->ts_isr_cmd) -
-		seg1 - seg2;
-	seg4 = (ctxp->ts_isr_data - ctxp->ts_isr_cmd) -
-		seg1 - seg2 - seg3;
-	seg5 = (ctxp->ts_data_nvme - ctxp->ts_isr_cmd) -
-		seg1 - seg2 - seg3 - seg4;
+	segsum = seg1;
+
+	seg2 = ctxp->ts_nvme_data - ctxp->ts_isr_cmd;
+	if (segsum > seg2)
+		return;
+	seg2 -= segsum;
+	segsum += seg2;
+
+	seg3 = ctxp->ts_data_wqput - ctxp->ts_isr_cmd;
+	if (segsum > seg3)
+		return;
+	seg3 -= segsum;
+	segsum += seg3;
+
+	seg4 = ctxp->ts_isr_data - ctxp->ts_isr_cmd;
+	if (segsum > seg4)
+		return;
+	seg4 -= segsum;
+	segsum += seg4;
+
+	seg5 = ctxp->ts_data_nvme - ctxp->ts_isr_cmd;
+	if (segsum > seg5)
+		return;
+	seg5 -= segsum;
+	segsum += seg5;
+
 
 	/* For auto rsp commands seg6 thru seg10 will be 0 */
 	if (ctxp->ts_nvme_status > ctxp->ts_data_nvme) {
-		seg6 = (ctxp->ts_nvme_status -
-			ctxp->ts_isr_cmd) -
-			seg1 - seg2 - seg3 - seg4 - seg5;
-		seg7 = (ctxp->ts_status_wqput -
-			ctxp->ts_isr_cmd) -
-			seg1 - seg2 - seg3 -
-			seg4 - seg5 - seg6;
-		seg8 = (ctxp->ts_isr_status -
-			ctxp->ts_isr_cmd) -
-			seg1 - seg2 - seg3 - seg4 -
-			seg5 - seg6 - seg7;
-		seg9 = (ctxp->ts_status_nvme -
-			ctxp->ts_isr_cmd) -
-			seg1 - seg2 - seg3 - seg4 -
-			seg5 - seg6 - seg7 - seg8;
+		seg6 = ctxp->ts_nvme_status - ctxp->ts_isr_cmd;
+		if (segsum > seg6)
+			return;
+		seg6 -= segsum;
+		segsum += seg6;
+
+		seg7 = ctxp->ts_status_wqput - ctxp->ts_isr_cmd;
+		if (segsum > seg7)
+			return;
+		seg7 -= segsum;
+		segsum += seg7;
+
+		seg8 = ctxp->ts_isr_status - ctxp->ts_isr_cmd;
+		if (segsum > seg8)
+			return;
+		seg8 -= segsum;
+		segsum += seg8;
+
+		seg9 = ctxp->ts_status_nvme - ctxp->ts_isr_cmd;
+		if (segsum > seg9)
+			return;
+		seg9 -= segsum;
+		segsum += seg9;
+
+		if (ctxp->ts_isr_status < ctxp->ts_isr_cmd)
+			return;
 		seg10 = (ctxp->ts_isr_status -
 			ctxp->ts_isr_cmd);
 	} else {
+		if (ctxp->ts_isr_data < ctxp->ts_isr_cmd)
+			return;
 		seg6 =  0;
 		seg7 =  0;
 		seg8 =  0;
@@ -519,7 +550,7 @@ lpfc_nvmet_xmt_fcp_op_cmp(struct lpfc_hba *phba, struct lpfc_iocbq *cmdwqe,
 		ctxp->entry_cnt++;
 
 #ifdef CONFIG_SCSI_LPFC_DEBUG_FS
-		if (phba->ktime_on) {
+		if (ctxp->ts_cmd_nvme) {
 			if (rsp->op == NVMET_FCOP_READDATA_RSP) {
 				ctxp->ts_isr_data =
 					cmdwqe->isr_timestamp;
@@ -553,7 +584,7 @@ lpfc_nvmet_xmt_fcp_op_cmp(struct lpfc_hba *phba, struct lpfc_iocbq *cmdwqe,
 #endif
 		rsp->done(rsp);
 #ifdef CONFIG_SCSI_LPFC_DEBUG_FS
-		if (phba->ktime_on)
+		if (ctxp->ts_cmd_nvme)
 			lpfc_nvmet_ktime(phba, ctxp);
 #endif
 		/* lpfc_nvmet_xmt_fcp_release() will recycle the context */
@@ -563,7 +594,7 @@ lpfc_nvmet_xmt_fcp_op_cmp(struct lpfc_hba *phba, struct lpfc_iocbq *cmdwqe,
 		memset(((char *)cmdwqe) + start_clean, 0,
 		       (sizeof(struct lpfc_iocbq) - start_clean));
 #ifdef CONFIG_SCSI_LPFC_DEBUG_FS
-		if (phba->ktime_on) {
+		if (ctxp->ts_cmd_nvme) {
 			ctxp->ts_isr_data = cmdwqe->isr_timestamp;
 			ctxp->ts_data_nvme = ktime_get_ns();
 		}
@@ -679,7 +710,7 @@ lpfc_nvmet_xmt_fcp_op(struct nvmet_fc_target_port *tgtport,
 	int rc;
 
 #ifdef CONFIG_SCSI_LPFC_DEBUG_FS
-	if (phba->ktime_on) {
+	if (ctxp->ts_cmd_nvme) {
 		if (rsp->op == NVMET_FCOP_RSP)
 			ctxp->ts_nvme_status = ktime_get_ns();
 		else
@@ -734,7 +765,7 @@ lpfc_nvmet_xmt_fcp_op(struct nvmet_fc_target_port *tgtport,
 	rc = lpfc_sli4_issue_wqe(phba, LPFC_FCP_RING, nvmewqeq);
 	if (rc == WQE_SUCCESS) {
 #ifdef CONFIG_SCSI_LPFC_DEBUG_FS
-		if (!phba->ktime_on)
+		if (!ctxp->ts_cmd_nvme)
 			return 0;
 		if (rsp->op == NVMET_FCOP_RSP)
 			ctxp->ts_status_wqput = ktime_get_ns();
@@ -1633,7 +1664,7 @@ lpfc_nvmet_unsol_fcp_buffer(struct lpfc_hba *phba,
 	spin_lock_init(&ctxp->ctxlock);
 
 #ifdef CONFIG_SCSI_LPFC_DEBUG_FS
-	if (phba->ktime_on) {
+	if (isr_timestamp) {
 		ctxp->ts_isr_cmd = isr_timestamp;
 		ctxp->ts_cmd_nvme = ktime_get_ns();
 		ctxp->ts_nvme_data = 0;
@@ -1644,6 +1675,8 @@ lpfc_nvmet_unsol_fcp_buffer(struct lpfc_hba *phba,
 		ctxp->ts_status_wqput = 0;
 		ctxp->ts_isr_status = 0;
 		ctxp->ts_status_nvme = 0;
+	} else {
+		ctxp->ts_cmd_nvme = 0;
 	}
 #endif