[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, 6 insertions, 3 deletions

diff --git a/include/scsi/scsi_device.h b/include/scsi/scsi_device.h
index 9af48cbf0036..92c4c3bd916d 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;