[SCSI] iscsi: lower queue depth

From Wang Zhenyu:

High queue depth was a problem for some targets so make queue_depth adjustable

From Mike Christie

Make default queue_depth a little lower

Signed-off-by: Mike Christie <michaelc@cs.wisc.edu>
Signed-off-by: Alex Aizman <itn780@yahoo.com>
Signed-off-by: Dmitry Yusupov <dmitry_yus@yahoo.com>
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>

diff --git a/drivers/scsi/iscsi_tcp.c b/drivers/scsi/iscsi_tcp.c
index 83e2f8c..5b14c40 100644 (file)
--- a/drivers/scsi/iscsi_tcp.c
+++ b/drivers/scsi/iscsi_tcp.c
@@ -2401,6 +2401,15 @@ fault:
        return 0;
 }
 
+static int
+iscsi_change_queue_depth(struct scsi_device *sdev, int depth)
+{
+       if (depth > ISCSI_MAX_CMD_PER_LUN)
+               depth = ISCSI_MAX_CMD_PER_LUN;
+       scsi_adjust_queue_depth(sdev, scsi_get_tag_type(sdev), depth);
+       return sdev->queue_depth;
+}
+
 static int
 iscsi_pool_init(struct iscsi_queue *q, int max, void ***items, int item_size)
 {
@@ -3260,13 +3269,14 @@ iscsi_r2tpool_free(struct iscsi_session *session)
 static struct scsi_host_template iscsi_sht = {
        .name                   = "iSCSI Initiator over TCP/IP, v."
                                  ISCSI_VERSION_STR,
-        .queuecommand           = iscsi_queuecommand,
+       .queuecommand           = iscsi_queuecommand,
+       .change_queue_depth     = iscsi_change_queue_depth,
        .can_queue              = ISCSI_XMIT_CMDS_MAX - 1,
        .sg_tablesize           = ISCSI_SG_TABLESIZE,
-       .cmd_per_lun            = ISCSI_CMD_PER_LUN,
-        .eh_abort_handler       = iscsi_eh_abort,
-        .eh_host_reset_handler = iscsi_eh_host_reset,
-        .use_clustering         = DISABLE_CLUSTERING,
+       .cmd_per_lun            = ISCSI_DEF_CMD_PER_LUN,
+       .eh_abort_handler       = iscsi_eh_abort,
+       .eh_host_reset_handler  = iscsi_eh_host_reset,
+       .use_clustering         = DISABLE_CLUSTERING,
        .proc_name              = "iscsi_tcp",
        .this_id                = -1,
 };

diff --git a/drivers/scsi/iscsi_tcp.h b/drivers/scsi/iscsi_tcp.h
index d23ae68..855f2df 100644 (file)
--- a/drivers/scsi/iscsi_tcp.h
+++ b/drivers/scsi/iscsi_tcp.h
@@ -71,7 +71,8 @@
 #define ISCSI_MGMT_CMDS_MAX            32      /* must be power of 2 */
 #define ISCSI_MGMT_ITT_OFFSET          0xa00
 #define ISCSI_SG_TABLESIZE             SG_ALL
-#define ISCSI_CMD_PER_LUN              128
+#define ISCSI_DEF_CMD_PER_LUN          32
+#define ISCSI_MAX_CMD_PER_LUN          128
 #define ISCSI_TCP_MAX_CMD_LEN          16
 
 #define ITT_MASK                       (0xfff)