[PATCH v4 5/7] scsi-ml: adds queue_depth ramp up code

[Vasu Dev <vasu.dev@intel.com>]

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>
---

 drivers/scsi/scsi.c        |   10 ++++++++--
 drivers/scsi/scsi_error.c  |   38 ++++++++++++++++++++++++++++++++++++++
 drivers/scsi/scsi_scan.c   |    3 +++
 drivers/scsi/scsi_sysfs.c  |   41 +++++++++++++++++++++++++++++++++++++++--
 include/scsi/scsi_device.h |    9 ++++++---
 5 files changed, 94 insertions(+), 7 deletions(-)

diff --git a/drivers/scsi/scsi.c b/drivers/scsi/scsi.c
index dd098ca..a60da55 100644
--- a/drivers/scsi/scsi.c
+++ b/drivers/scsi/scsi.c
@@ -940,10 +940,16 @@ EXPORT_SYMBOL(scsi_adjust_queue_depth);
  */
 int scsi_track_queue_full(struct scsi_device *sdev, int depth)
 {
-	if ((jiffies >> 4) == sdev->last_queue_full_time)
+
+	/*
+	 * Don't let QUEUE_FULLs on the same
+	 * jiffies count, they could all be from
+	 * same event.
+	 */
+	if ((jiffies >> 4) == (sdev->last_queue_full_time >> 4))
 		return 0;
 
-	sdev->last_queue_full_time = (jiffies >> 4);
+	sdev->last_queue_full_time = jiffies;
 	if (sdev->last_queue_full_depth != depth) {
 		sdev->last_queue_full_count = 1;
 		sdev->last_queue_full_depth = depth;
diff --git a/drivers/scsi/scsi_error.c b/drivers/scsi/scsi_error.c
index 7b1e20f..08ed506 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:
diff --git a/drivers/scsi/scsi_scan.c b/drivers/scsi/scsi_scan.c
index cb6338f..2847a86 100644
--- a/drivers/scsi/scsi_scan.c
+++ b/drivers/scsi/scsi_scan.c
@@ -251,6 +251,7 @@ static struct scsi_device *scsi_alloc_sdev(struct scsi_target *starget,
 	sdev->model = scsi_null_device_strs;
 	sdev->rev = scsi_null_device_strs;
 	sdev->host = shost;
+	sdev->queue_ramp_up_period = SCSI_DEFAULT_RAMP_UP_PERIOD;
 	sdev->id = starget->id;
 	sdev->lun = lun;
 	sdev->channel = starget->channel;
@@ -940,6 +941,8 @@ static int scsi_add_lun(struct scsi_device *sdev, unsigned char *inq_result,
 		}
 	}
 
+	sdev->max_queue_depth = sdev->queue_depth;
+
 	/*
 	 * Ok, the device is now all set up, we can
 	 * register it and tell the rest of the kernel
diff --git a/drivers/scsi/scsi_sysfs.c b/drivers/scsi/scsi_sysfs.c
index 4c59336..3a9e805 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)
 {
@@ -870,8 +903,12 @@ int scsi_sysfs_add_sdev(struct scsi_device *sdev)
 	get_device(&sdev->sdev_gendev);
 
 	/* 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) {
diff --git a/include/scsi/scsi_device.h b/include/scsi/scsi_device.h
index 9af48cb..92c4c3b 100644
--- a/include/scsi/scsi_device.h
+++ b/include/scsi/scsi_device.h
@@ -81,11 +81,14 @@ struct scsi_device {
 	struct list_head starved_entry;
 	struct scsi_cmnd *current_cmnd;	/* currently active command */
 	unsigned short queue_depth;	/* How deep of a queue we want */
+	unsigned short max_queue_depth;	/* max queue depth */
 	unsigned short last_queue_full_depth; /* These two are used by */
 	unsigned short last_queue_full_count; /* scsi_track_queue_full() */
-	unsigned long last_queue_full_time;/* don't let QUEUE_FULLs on the same
-					   jiffie count on our counter, they
-					   could all be from the same event. */
+	unsigned long last_queue_full_time;	/* last queue full time */
+	unsigned long queue_ramp_up_period;	/* ramp up period in jiffies */
+#define SCSI_DEFAULT_RAMP_UP_PERIOD	(120 * HZ)
+
+	unsigned long last_queue_ramp_up;	/* last queue ramp up time */
 
 	unsigned int id, lun, channel;