[SCSI] add queue_depth ramp up code

Current FC HBA queue_depth ramp up code depends on last queue
full time. The sdev already  has last_queue_full_time field to
track last queue full time but stored value is truncated by
last four bits.

So this patch updates last_queue_full_time without truncating
last 4 bits to store full value and then updates its only
current usages in scsi_track_queue_full to ignore last four bits
to keep current usages same while also use this field
in added ramp up code.

Adds scsi_handle_queue_ramp_up to ramp up queue_depth on
successful completion of IO. The scsi_handle_queue_ramp_up will
do ramp up on all luns of a target, just same as ramp down done
on all luns on a target.

The ramp up is skipped in case the change_queue_depth is not
supported by LLD or already reached to added max_queue_depth.

Updates added max_queue_depth on every new update to default
queue_depth value.

The ramp up is also skipped if lapsed time since either last
queue ramp up or down is less than LLD specified
queue_ramp_up_period.

Adds queue_ramp_up_period to sysfs but only if change_queue_depth
is supported since ramp up and queue_ramp_up_period is needed only
in case change_queue_depth is supported first.

Initializes queue_ramp_up_period to 120HZ jiffies as initial
default value, it is same as used in existing lpfc and qla2xxx.

-v2
 Combined all ramp code into this single patch.

-v3
 Moves max_queue_depth initialization after slave_configure is
called from after slave_alloc calling done. Also adjusted
max_queue_depth check to skip ramp up if current queue_depth
is >= max_queue_depth.

-v4
 Changes sdev->queue_ramp_up_period unit to ms when using sysfs i/f
to store or show its value.

Signed-off-by: Vasu Dev <vasu.dev@intel.com>
Tested-by: Christof Schmitt <christof.schmitt@de.ibm.com>
Tested-by: Giridhar Malavali <giridhar.malavali@qlogic.com>
Signed-off-by: James Bottomley <James.Bottomley@suse.de>

1 files changed, 38 insertions, 0 deletions

diff --git a/drivers/scsi/scsi_error.c b/drivers/scsi/scsi_error.c
index 7b1e20fee90..08ed506e605 100644
--- a/drivers/scsi/scsi_error.c
+++ b/drivers/scsi/scsi_error.c
@@ -331,6 +331,42 @@ static int scsi_check_sense(struct scsi_cmnd *scmd)
 	}
 }
 
+static void scsi_handle_queue_ramp_up(struct scsi_device *sdev)
+{
+	struct scsi_host_template *sht = sdev->host->hostt;
+	struct scsi_device *tmp_sdev;
+
+	if (!sht->change_queue_depth ||
+	    sdev->queue_depth >= sdev->max_queue_depth)
+		return;
+
+	if (time_before(jiffies,
+	    sdev->last_queue_ramp_up + sdev->queue_ramp_up_period))
+		return;
+
+	if (time_before(jiffies,
+	    sdev->last_queue_full_time + sdev->queue_ramp_up_period))
+		return;
+
+	/*
+	 * Walk all devices of a target and do
+	 * ramp up on them.
+	 */
+	shost_for_each_device(tmp_sdev, sdev->host) {
+		if (tmp_sdev->channel != sdev->channel ||
+		    tmp_sdev->id != sdev->id ||
+		    tmp_sdev->queue_depth == sdev->max_queue_depth)
+			continue;
+		/*
+		 * call back into LLD to increase queue_depth by one
+		 * with ramp up reason code.
+		 */
+		sht->change_queue_depth(tmp_sdev, tmp_sdev->queue_depth + 1,
+					SCSI_QDEPTH_RAMP_UP);
+		sdev->last_queue_ramp_up = jiffies;
+	}
+}
+
 static void scsi_handle_queue_full(struct scsi_device *sdev)
 {
 	struct scsi_host_template *sht = sdev->host->hostt;
@@ -393,6 +429,7 @@ static int scsi_eh_completed_normally(struct scsi_cmnd *scmd)
 	 */
 	switch (status_byte(scmd->result)) {
 	case GOOD:
+		scsi_handle_queue_ramp_up(scmd->device);
 	case COMMAND_TERMINATED:
 		return SUCCESS;
 	case CHECK_CONDITION:
@@ -1425,6 +1462,7 @@ int scsi_decide_disposition(struct scsi_cmnd *scmd)
 		 */
 		return ADD_TO_MLQUEUE;
 	case GOOD:
+		scsi_handle_queue_ramp_up(scmd->device);
 	case COMMAND_TERMINATED:
 		return SUCCESS;
 	case TASK_ABORTED: