diff --git a/lib/iscsi/iscsi.h b/lib/iscsi/iscsi.h
index 37964999e..35c5628f5 100644
--- a/lib/iscsi/iscsi.h
+++ b/lib/iscsi/iscsi.h
@@ -107,7 +107,11 @@
  */
 #define MAX_LARGE_DATAIN_PER_CONNECTION 64
 
-#define NUM_PDU_PER_CONNECTION	(2 * (SPDK_ISCSI_MAX_QUEUE_DEPTH + MAX_LARGE_DATAIN_PER_CONNECTION + 8))
+/*
+ * Defines default maximum queue depth per connection and this can be
+ * changed by configuration file.
+ */
+#define DEFAULT_MAX_QUEUE_DEPTH	64
 
 #define SPDK_ISCSI_MAX_BURST_LENGTH	\
 		(SPDK_ISCSI_MAX_RECV_DATA_SEGMENT_LENGTH * MAX_DATA_OUT_PER_CONNECTION)
@@ -276,6 +280,7 @@ struct spdk_iscsi_globals {
 	uint32_t MaxSessions;
 	uint32_t MaxConnectionsPerSession;
 	uint32_t MaxConnections;
+	uint32_t MaxQueueDepth;
 	uint32_t DefaultTime2Wait;
 	uint32_t DefaultTime2Retain;
 	uint32_t ImmediateData;
diff --git a/lib/iscsi/iscsi_subsystem.c b/lib/iscsi/iscsi_subsystem.c
index 0771dc006..68c7ba941 100644
--- a/lib/iscsi/iscsi_subsystem.c
+++ b/lib/iscsi/iscsi_subsystem.c
@@ -71,6 +71,7 @@ static void *g_fini_cb_arg;
 "  MaxSessions %d\n" \
 "  MaxConnectionsPerSession %d\n" \
 "  MaxConnections %d\n" \
+"  MaxQueueDepth %d\n" \
 "\n" \
 "  # iSCSI initial parameters negotiate with initiators\n" \
 "  # NOTE: incorrect values might crash\n" \
@@ -105,6 +106,7 @@ spdk_iscsi_config_dump_section(FILE *fp)
 		g_spdk_iscsi.timeout, authmethod, authgroup,
 		g_spdk_iscsi.MaxSessions, g_spdk_iscsi.MaxConnectionsPerSession,
 		g_spdk_iscsi.MaxConnections,
+		g_spdk_iscsi.MaxQueueDepth,
 		g_spdk_iscsi.DefaultTime2Wait, g_spdk_iscsi.DefaultTime2Retain,
 		(g_spdk_iscsi.ImmediateData == 1) ? "Yes" : "No",
 		g_spdk_iscsi.ErrorRecoveryLevel);
@@ -320,7 +322,8 @@ spdk_mobj_ctor(struct rte_mempool *mp, __attribute__((unused)) void *arg,
 #endif
 }
 
-#define PDU_POOL_SIZE(iscsi)	(iscsi->MaxConnections * NUM_PDU_PER_CONNECTION)
+#define NUM_PDU_PER_CONNECTION(iscsi)	(2 * (iscsi->MaxQueueDepth + MAX_LARGE_DATAIN_PER_CONNECTION + 8))
+#define PDU_POOL_SIZE(iscsi)	(iscsi->MaxConnections * NUM_PDU_PER_CONNECTION(iscsi))
 #define IMMEDIATE_DATA_POOL_SIZE(iscsi)	(iscsi->MaxConnections * 128)
 #define DATA_OUT_POOL_SIZE(iscsi)	(iscsi->MaxConnections * MAX_DATA_OUT_PER_CONNECTION)
 
@@ -533,6 +536,7 @@ spdk_iscsi_log_globals(void)
 	SPDK_DEBUGLOG(SPDK_TRACE_ISCSI, "MaxSessions %d\n", g_spdk_iscsi.MaxSessions);
 	SPDK_DEBUGLOG(SPDK_TRACE_ISCSI, "MaxConnectionsPerSession %d\n",
 		      g_spdk_iscsi.MaxConnectionsPerSession);
+	SPDK_DEBUGLOG(SPDK_TRACE_ISCSI, "MaxQueueDepth %d\n", g_spdk_iscsi.MaxQueueDepth);
 	SPDK_DEBUGLOG(SPDK_TRACE_ISCSI, "DefaultTime2Wait %d\n",
 		      g_spdk_iscsi.DefaultTime2Wait);
 	SPDK_DEBUGLOG(SPDK_TRACE_ISCSI, "DefaultTime2Retain %d\n",
@@ -577,6 +581,7 @@ spdk_iscsi_read_parameters_from_config_file(struct spdk_conf_section *sp)
 	char *authfile, *nodebase;
 	int MaxSessions;
 	int MaxConnectionsPerSession;
+	int MaxQueueDepth;
 	int DefaultTime2Wait;
 	int DefaultTime2Retain;
 	int ErrorRecoveryLevel;
@@ -639,6 +644,18 @@ spdk_iscsi_read_parameters_from_config_file(struct spdk_conf_section *sp)
 			g_spdk_iscsi.MaxConnectionsPerSession = MaxConnectionsPerSession;
 		}
 	}
+
+	MaxQueueDepth = spdk_conf_section_get_intval(sp, "MaxQueueDepth");
+	if (MaxQueueDepth >= 0) {
+		if (MaxQueueDepth == 0) {
+			SPDK_ERRLOG("MaxQueueDepth == 0 invalid, ignoring\n");
+		} else if (MaxQueueDepth > 256) {
+			SPDK_ERRLOG("MaxQueueDepth == %d invalid, ignoring\n", MaxQueueDepth);
+		} else {
+			g_spdk_iscsi.MaxQueueDepth = MaxQueueDepth;
+		}
+	}
+
 	DefaultTime2Wait = spdk_conf_section_get_intval(sp, "DefaultTime2Wait");
 	if (DefaultTime2Wait >= 0) {
 		if (DefaultTime2Wait > 3600) {
@@ -745,6 +762,7 @@ spdk_iscsi_app_read_parameters(void)
 
 	g_spdk_iscsi.MaxSessions = DEFAULT_MAX_SESSIONS;
 	g_spdk_iscsi.MaxConnectionsPerSession = DEFAULT_MAX_CONNECTIONS_PER_SESSION;
+	g_spdk_iscsi.MaxQueueDepth = DEFAULT_MAX_QUEUE_DEPTH;
 	g_spdk_iscsi.DefaultTime2Wait = DEFAULT_DEFAULTTIME2WAIT;
 	g_spdk_iscsi.DefaultTime2Retain = DEFAULT_DEFAULTTIME2RETAIN;
 	g_spdk_iscsi.ImmediateData = DEFAULT_IMMEDIATEDATA;
diff --git a/lib/iscsi/tgt_node.c b/lib/iscsi/tgt_node.c
index ae52ae00e..ed5304472 100644
--- a/lib/iscsi/tgt_node.c
+++ b/lib/iscsi/tgt_node.c
@@ -829,13 +829,13 @@ spdk_iscsi_tgt_node_construct(int target_index,
 	target->header_digest = header_digest;
 	target->data_digest = data_digest;
 
-	if (queue_depth > SPDK_ISCSI_MAX_QUEUE_DEPTH) {
-		SPDK_DEBUGLOG(SPDK_TRACE_ISCSI, "QueueDepth %d > Max %d.  Using %d instead.\n",
-			      queue_depth, SPDK_ISCSI_MAX_QUEUE_DEPTH,
-			      SPDK_ISCSI_MAX_QUEUE_DEPTH);
-		queue_depth = SPDK_ISCSI_MAX_QUEUE_DEPTH;
+	if (queue_depth > 0 && ((uint32_t)queue_depth <= g_spdk_iscsi.MaxQueueDepth)) {
+		target->queue_depth = queue_depth;
+	} else {
+		SPDK_DEBUGLOG(SPDK_TRACE_ISCSI, "QueueDepth %d is invalid and %d is used instead.\n",
+			      queue_depth, g_spdk_iscsi.MaxQueueDepth);
+		target->queue_depth = g_spdk_iscsi.MaxQueueDepth;
 	}
-	target->queue_depth = queue_depth;
 
 	rc = spdk_iscsi_tgt_node_register(target);
 	if (rc != 0) {
@@ -1019,7 +1019,7 @@ spdk_cf_add_iscsi_tgt_node(struct spdk_conf_section *sp)
 
 	val = spdk_conf_section_get_val(sp, "QueueDepth");
 	if (val == NULL) {
-		queue_depth = SPDK_ISCSI_MAX_QUEUE_DEPTH;
+		queue_depth = g_spdk_iscsi.MaxQueueDepth;
 	} else {
 		queue_depth = (int) strtol(val, NULL, 10);
 	}
diff --git a/lib/iscsi/tgt_node.h b/lib/iscsi/tgt_node.h
index e232d3084..084cf3426 100644
--- a/lib/iscsi/tgt_node.h
+++ b/lib/iscsi/tgt_node.h
@@ -44,9 +44,8 @@ struct spdk_iscsi_init_grp;
 struct spdk_iscsi_portal_grp;
 struct spdk_iscsi_portal;
 
-#define SPDK_ISCSI_MAX_QUEUE_DEPTH	64
 #define MAX_TARGET_MAP			256
-#define SPDK_TN_TAG_MAX 0x0000ffff
+#define SPDK_TN_TAG_MAX 		0x0000ffff
 
 struct spdk_iscsi_ig_map {
 	struct spdk_iscsi_init_grp *ig;