[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, 39 insertions, 2 deletions

diff --git a/drivers/scsi/scsi_sysfs.c b/drivers/scsi/scsi_sysfs.c
index a48782866b22..758598ff3b90 100644
--- a/drivers/scsi/scsi_sysfs.c
+++ b/drivers/scsi/scsi_sysfs.c
@@ -771,6 +771,8 @@ sdev_store_queue_depth_rw(struct device *dev, struct device_attribute *attr,
 	if (retval < 0)
 		return retval;
 
+	sdev->max_queue_depth = sdev->queue_depth;
+
 	return count;
 }
 
@@ -779,6 +781,37 @@ static struct device_attribute sdev_attr_queue_depth_rw =
 	       sdev_store_queue_depth_rw);
 
 static ssize_t
+sdev_show_queue_ramp_up_period(struct device *dev,
+			       struct device_attribute *attr,
+			       char *buf)
+{
+	struct scsi_device *sdev;
+	sdev = to_scsi_device(dev);
+	return snprintf(buf, 20, "%u\n",
+			jiffies_to_msecs(sdev->queue_ramp_up_period));
+}
+
+static ssize_t
+sdev_store_queue_ramp_up_period(struct device *dev,
+				struct device_attribute *attr,
+				const char *buf, size_t count)
+{
+	struct scsi_device *sdev = to_scsi_device(dev);
+	unsigned long period;
+
+	if (strict_strtoul(buf, 10, &period))
+		return -EINVAL;
+
+	sdev->queue_ramp_up_period = msecs_to_jiffies(period);
+	return period;
+}
+
+static struct device_attribute sdev_attr_queue_ramp_up_period =
+	__ATTR(queue_ramp_up_period, S_IRUGO | S_IWUSR,
+	       sdev_show_queue_ramp_up_period,
+	       sdev_store_queue_ramp_up_period);
+
+static ssize_t
 sdev_store_queue_type_rw(struct device *dev, struct device_attribute *attr,
 			 const char *buf, size_t count)
 {
@@ -866,8 +899,12 @@ int scsi_sysfs_add_sdev(struct scsi_device *sdev)
 	}
 
 	/* create queue files, which may be writable, depending on the host */
-	if (sdev->host->hostt->change_queue_depth)
-		error = device_create_file(&sdev->sdev_gendev, &sdev_attr_queue_depth_rw);
+	if (sdev->host->hostt->change_queue_depth) {
+		error = device_create_file(&sdev->sdev_gendev,
+					   &sdev_attr_queue_depth_rw);
+		error = device_create_file(&sdev->sdev_gendev,
+					   &sdev_attr_queue_ramp_up_period);
+	}
 	else
 		error = device_create_file(&sdev->sdev_gendev, &dev_attr_queue_depth);
 	if (error) {