[PATCH v2] ufs: core: Only collect timestamps if the monitoring functionality is enabled

[PATCH v2] ufs: core: Only collect timestamps if the monitoring functionality is enabled

[Bart Van Assche]

Every ktime_get() call in the hot path has a measurable impact on IOPS.
Hence, only collect timestamps if the monitoring functionality is enabled.

See also commit 1d8613a23f3c ("scsi: ufs: core: Introduce HBA performance
monitor sysfs nodes"; v5.14).

Cc: Can Guo <cang@codeaurora.org>
Cc: Bean Huo <beanhuo@micron.com>
Cc: Daejun Park <daejun7.park@samsung.com>
Reviewed-by: Peter Wang <peter.wang@mediatek.com>
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
---

Changes compared to v1: in ufshcd_print_tr(), only report timestamps if the
    monitoring functionality is enabled.

 drivers/ufs/core/ufshcd.c | 26 ++++++++++++++++----------
 1 file changed, 16 insertions(+), 10 deletions(-)

diff --git a/drivers/ufs/core/ufshcd.c b/drivers/ufs/core/ufshcd.c
index 18a22e578a1d..3bd4e5f92ad7 100644
--- a/drivers/ufs/core/ufshcd.c
+++ b/drivers/ufs/core/ufshcd.c
@@ -607,10 +607,12 @@ void ufshcd_print_tr(struct ufs_hba *hba, int tag, bool pr_prdt)
 
 	lrbp = &hba->lrb[tag];
 
-	dev_err(hba->dev, "UPIU[%d] - issue time %lld us\n",
-			tag, div_u64(lrbp->issue_time_stamp_local_clock, 1000));
-	dev_err(hba->dev, "UPIU[%d] - complete time %lld us\n",
-			tag, div_u64(lrbp->compl_time_stamp_local_clock, 1000));
+	if (hba->monitor.enabled) {
+		dev_err(hba->dev, "UPIU[%d] - issue time %lld us\n", tag,
+			div_u64(lrbp->issue_time_stamp_local_clock, 1000));
+		dev_err(hba->dev, "UPIU[%d] - complete time %lld us\n", tag,
+			div_u64(lrbp->compl_time_stamp_local_clock, 1000));
+	}
 	dev_err(hba->dev,
 		"UPIU[%d] - Transfer Request Descriptor phys@0x%llx\n",
 		tag, (u64)lrbp->utrd_dma_addr);
@@ -2357,10 +2359,12 @@ void ufshcd_send_command(struct ufs_hba *hba, unsigned int task_tag,
 	struct ufshcd_lrb *lrbp = &hba->lrb[task_tag];
 	unsigned long flags;
 
-	lrbp->issue_time_stamp = ktime_get();
-	lrbp->issue_time_stamp_local_clock = local_clock();
-	lrbp->compl_time_stamp = ktime_set(0, 0);
-	lrbp->compl_time_stamp_local_clock = 0;
+	if (hba->monitor.enabled) {
+		lrbp->issue_time_stamp = ktime_get();
+		lrbp->issue_time_stamp_local_clock = local_clock();
+		lrbp->compl_time_stamp = ktime_set(0, 0);
+		lrbp->compl_time_stamp_local_clock = 0;
+	}
 	ufshcd_add_command_trace(hba, task_tag, UFS_CMD_SEND);
 	if (lrbp->cmd)
 		ufshcd_clk_scaling_start_busy(hba);
@@ -5622,8 +5626,10 @@ void ufshcd_compl_one_cqe(struct ufs_hba *hba, int task_tag,
 	enum utp_ocs ocs;
 
 	lrbp = &hba->lrb[task_tag];
-	lrbp->compl_time_stamp = ktime_get();
-	lrbp->compl_time_stamp_local_clock = local_clock();
+	if (hba->monitor.enabled) {
+		lrbp->compl_time_stamp = ktime_get();
+		lrbp->compl_time_stamp_local_clock = local_clock();
+	}
 	cmd = lrbp->cmd;
 	if (cmd) {
 		if (unlikely(ufshcd_should_inform_monitor(hba, lrbp)))

Re: [PATCH v2] ufs: core: Only collect timestamps if the monitoring functionality is enabled

[Martin K. Petersen]

Bart,

> Every ktime_get() call in the hot path has a measurable impact on
> IOPS. Hence, only collect timestamps if the monitoring functionality
> is enabled.

Applied to 6.18/scsi-staging, thanks!

-- 
Martin K. Petersen