diff --git a/src/app.toml b/src/app.toml
index ac30016..83a8f4b 100644
--- a/src/app.toml
+++ b/src/app.toml
@@ -5,12 +5,15 @@ thread_num = 1
 [PACKET_IO]
 """
 example1:
-
 run_mode = pcap_live
 interface = [eth0, eth1]
 
+example2:
+run_mode = marsio
+work_thread_num = 10  # Prompt marsio how many threads to start to receive packets
+interface = [eth0]
 
-
-"""
-run_mode = pcap_live  # three mode: pcap_file/pcap_live/marsio
-interface = [eth0, eth1]
+example3:
+run_mode = pcap_file
+pcap_file_path = /tmp/pcapfile/001.pcap # if single file, specify dir+filename; if pcapfile directory, specify dir
+"""
\ No newline at end of file
diff --git a/src/main.cpp b/src/main.cpp
index 5b2e558..e47815a 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -55,7 +55,7 @@ void packet_io_loop(struct packet_io_loop_arg *arg)
 struct packet_io_device *
 packet_io_init(const char *instance_name, const enum packet_io_run_mode mode, const int wrk_thread_num)
 {
-	struct packet_io_instance *ppio_inst = packet_io_instance_create(instance_name, mode, wrk_thread_num);
+	struct packet_io_instance *ppio_inst = packet_io_instance_create(instance_name, mode);
 	if (nullptr == ppio_inst) {
 		log_error(ST_ERR_PIO_INSTANCE, "packet_io instance init failed.");
 		return nullptr;
diff --git a/src/packet_io/marsio_mode/pio_marsio.cpp b/src/packet_io/marsio_mode/pio_marsio.cpp
index b94dd77..73c9f31 100644
--- a/src/packet_io/marsio_mode/pio_marsio.cpp
+++ b/src/packet_io/marsio_mode/pio_marsio.cpp
@@ -283,7 +283,7 @@ int pio_marsio_device_open(struct packet_io_device *pdev)
 	}
 
 	pdev->entity.marsio_dev_ctx->pio_dev = pdev;
-	
+
 	struct mr_instance *mr_inst_handle = pdev->ppio_inst->entity.marsio_inst_ctx->mr_inst_handle;
 	/* marsio_open_device() return marsio device handle*/
 	pdev->entity.marsio_dev_ctx->mr_dev_handle = \
@@ -353,7 +353,7 @@ void pio_marsio_device_pkt_free(struct packet_io_device *pdev, uint32_t qid, str
 	g_marsio_dll_func.marsio_buff_free(mr_inst, (marsio_buff_t **)pkts, nr_pkts, MARSIO_SOCKET_ID_ANY, qid);
 }
 
-static int marsio_instance_init(struct packet_io_instance *pinst, int wrk_thread_num) 
+static int marsio_instance_init(struct packet_io_instance *pinst) 
 {
 	int ret = -1;
 	ret = pio_get_marsio_dll_function_entries();
@@ -368,6 +368,7 @@ static int marsio_instance_init(struct packet_io_instance *pinst, int wrk_thread
 		return -1;
 	}
 
+	int wrk_thread_num = g_engine_instance.config.packet_io.thread_num;
 	/* TODO: MARSIO_OPT_THREAD_NUM */
 	ret = g_marsio_dll_func.marsio_option_set(pinst->entity.marsio_inst_ctx->mr_inst_handle, 
 											  MARSIO_OPT_THREAD_NUM, 
@@ -394,7 +395,7 @@ static int marsio_instance_init(struct packet_io_instance *pinst, int wrk_thread
  *
  *	@param: pinst(in/out) 
  */
-int pio_marsio_instance_create(struct packet_io_instance *pinst, int wrk_thread_num) 
+int pio_marsio_instance_create(struct packet_io_instance *pinst) 
 {
 	if (nullptr == pinst) {
 		log_error(ST_ERR_PIO_MARSIO_INSTANCE, "invalid marsio instance pointer.");
@@ -408,7 +409,7 @@ int pio_marsio_instance_create(struct packet_io_instance *pinst, int wrk_thread_
 	}
 
 	/* instance init */
-    int ret = marsio_instance_init(pinst, wrk_thread_num);
+    int ret = marsio_instance_init(pinst);
     if (ret < 0) {
         log_error(ST_ERR_PIO_MARSIO_INSTANCE, "marsio instance init failed.");
         return -1;
diff --git a/src/packet_io/marsio_mode/pio_marsio.h b/src/packet_io/marsio_mode/pio_marsio.h
index fa6d736..f10e160 100644
--- a/src/packet_io/marsio_mode/pio_marsio.h
+++ b/src/packet_io/marsio_mode/pio_marsio.h
@@ -83,7 +83,7 @@ struct pio_marsio_instance_context {
 };
 
 /**  
- * struct pio_marsio_device_context - marsio device context
+ * @brief struct pio_marsio_device_context - marsio device context
  * @mr_dev_handle:      marsio device handle 
  *                      if marsio device receive packets, use mr_dev_handle
  * @mr_sendpath_handle: marsio sendpath handle
@@ -96,6 +96,21 @@ struct pio_marsio_device_context {
     struct packet_io_device *pio_dev;
 };
 
+/**
+ * @brief 
+ * 
+ * @param pinst 
+ * @return int 
+ */
+int pio_marsio_instance_create(struct packet_io_instance *pinst);
+
+/**
+ * @brief 
+ * 
+ * @param pinst 
+ */
+void pio_marsio_instance_destroy(struct packet_io_instance *pinst);
+
 /**
  * @brief open marsio device
  *
@@ -145,10 +160,6 @@ int pio_marsio_device_send(struct packet_io_device *pdev, uint32_t txq_id, struc
 */
 void pio_marsio_device_pkt_free(struct packet_io_device *pdev, uint32_t qid, struct packet **pkts, int nr_pkts);
 
-int pio_marsio_instance_create(struct packet_io_instance *pinst, int wrk_thread_num);
-
-void pio_marsio_instance_destroy(struct packet_io_instance *pinst);
-
 void *pio_marsio_device_buff_ctrlzone(struct packet *p);
 
 char *pio_marsio_device_buff_mtod(struct packet *p);
diff --git a/src/packet_io/packet_io.cpp b/src/packet_io/packet_io.cpp
index 56ec943..770c5b4 100644
--- a/src/packet_io/packet_io.cpp
+++ b/src/packet_io/packet_io.cpp
@@ -72,17 +72,9 @@ struct pio_instance_operations pio_instance_ops_array[PACKET_IO_RUN_MODE_MAX] =
 };
 
 struct packet_io_instance *
-packet_io_instance_create(const char *inst_name, const enum packet_io_run_mode mode, const int wrk_thread_num) 
+packet_io_instance_create(const char *inst_name, const enum packet_io_run_mode mode) 
 {
-	if (nullptr == inst_name) {
-		return nullptr;
-	}
-
-	if (mode < PACKET_IO_RUN_MODE_PCAP_FILE || mode >= PACKET_IO_RUN_MODE_MAX) {
-		return nullptr;
-	}
-
-	if (wrk_thread_num < 0) {
+	if (nullptr == inst_name || mode < PACKET_IO_RUN_MODE_PCAP_FILE || mode >= PACKET_IO_RUN_MODE_MAX) {
 		return nullptr;
 	}
 
@@ -96,7 +88,7 @@ packet_io_instance_create(const char *inst_name, const enum packet_io_run_mode m
 	pio_instance->mode = mode;
 	pio_instance->inst_ops = &pio_instance_ops_array[mode];
 	
-	int ret = pio_instance->inst_ops->create(pio_instance, wrk_thread_num);
+	int ret = pio_instance->inst_ops->create(pio_instance);
 	if (ret < 0) {
 		log_error(ST_ERR_PIO_INSTANCE, "packet_io instance create failed.");
 		return nullptr;
diff --git a/src/packet_io/packet_io.h b/src/packet_io/packet_io.h
index abbc815..9c58192 100644
--- a/src/packet_io/packet_io.h
+++ b/src/packet_io/packet_io.h
@@ -26,7 +26,7 @@
 **/
 
 struct pio_instance_operations {
-	int (*create)(struct packet_io_instance *pinst, int wrk_thread_num);
+	int (*create)(struct packet_io_instance *pinst);
 
 	void (*destroy)(struct packet_io_instance *pinst);
 };
@@ -104,11 +104,9 @@ struct packet_io_device {
  *
  * @param instance_name:     packet_io instance name
  * @param mode:              packet_io run mode
- * @param wrk_thread_num:    expected number of packet receiving threads, which will be created by packet_io,
- * 							 this param is useful only in marsio mode
 **/
 struct packet_io_instance *
-packet_io_instance_create(const char *instance_name, const enum packet_io_run_mode mode, const int wrk_thread_num);
+packet_io_instance_create(const char *instance_name, const enum packet_io_run_mode mode);
 
 /* destroy packet_io instance */
 void packet_io_instance_destroy(struct packet_io_instance *pinst);
diff --git a/src/packet_io/pcap_file_mode/pio_pcap_file.cpp b/src/packet_io/pcap_file_mode/pio_pcap_file.cpp
index 14c8eea..d84f227 100644
--- a/src/packet_io/pcap_file_mode/pio_pcap_file.cpp
+++ b/src/packet_io/pcap_file_mode/pio_pcap_file.cpp
@@ -612,7 +612,7 @@ void pio_pcap_file_device_pkt_free(__unused struct packet_io_device *pdev, __unu
     }
 }
 
-int pio_pcap_file_instance_create(struct packet_io_instance *pinst, __unused int wrk_thread_num) 
+int pio_pcap_file_instance_create(struct packet_io_instance *pinst) 
 {
     if (nullptr == pinst) {
         log_error(ST_ERR_PIO_PCAP_FILE_INSTANCE, "invalid pcap file instance pointer.");
diff --git a/src/packet_io/pcap_file_mode/pio_pcap_file.h b/src/packet_io/pcap_file_mode/pio_pcap_file.h
index b47bb78..498cda6 100644
--- a/src/packet_io/pcap_file_mode/pio_pcap_file.h
+++ b/src/packet_io/pcap_file_mode/pio_pcap_file.h
@@ -97,6 +97,21 @@ struct pio_pcap_file_device_context {
     struct packet_io_device *pio_dev;
 };
 
+/**
+ * @brief 
+ * 
+ * @param pinst 
+ * @return int 
+ */
+int pio_pcap_file_instance_create(struct packet_io_instance *pinst);
+
+/**
+ * @brief 
+ * 
+ * @param pinst 
+ */
+void pio_pcap_file_instance_destroy(struct packet_io_instance *pinst);
+
 /**
  * @brief open pcap_file device
  *
@@ -116,10 +131,6 @@ int pio_pcap_file_device_receive(struct packet_io_device *pdev, uint32_t rxq_id,
 
 void pio_pcap_file_device_pkt_free(struct packet_io_device *pdev, uint32_t qid, struct packet **pkts, int nr_pkts);
 
-int pio_pcap_file_instance_create(struct packet_io_instance *pinst, int wrk_thread_num);
-
-void pio_pcap_file_instance_destroy(struct packet_io_instance *pinst);
-
 void *pio_pcap_file_device_buff_ctrlzone(struct packet *p);
 
 char *pio_pcap_file_device_buff_mtod(struct packet *p);
diff --git a/src/packet_io/pcap_live_mode/pio_pcap_live.cpp b/src/packet_io/pcap_live_mode/pio_pcap_live.cpp
index 1833b53..c896fe7 100644
--- a/src/packet_io/pcap_live_mode/pio_pcap_live.cpp
+++ b/src/packet_io/pcap_live_mode/pio_pcap_live.cpp
@@ -243,7 +243,7 @@ void pio_pcap_live_device_pkt_free(__unused struct packet_io_device *pdev, __unu
     }
 }
 
-int pio_pcap_live_instance_create(struct packet_io_instance *pinst, __unused int wrk_thread_num)
+int pio_pcap_live_instance_create(struct packet_io_instance *pinst)
 {
     if (nullptr == pinst) {
         log_error(ST_ERR_PIO_PCAP_LIVE_INSTANCE, "invalid pcap live instance pointer.");
diff --git a/src/packet_io/pcap_live_mode/pio_pcap_live.h b/src/packet_io/pcap_live_mode/pio_pcap_live.h
index a9f351d..02bf4cc 100644
--- a/src/packet_io/pcap_live_mode/pio_pcap_live.h
+++ b/src/packet_io/pcap_live_mode/pio_pcap_live.h
@@ -56,6 +56,22 @@ struct pio_pcap_live_device_context {
     struct packet_io_device *pio_dev;
 };
 
+/**
+ * @brief 
+ * 
+ * @param pinst 
+ * @param wrk_thread_num 
+ * @return int 
+ */
+int pio_pcap_live_instance_create(struct packet_io_instance *pinst);
+
+/**
+ * @brief 
+ * 
+ * @param pinst 
+ */
+void pio_pcap_live_instance_destroy(struct packet_io_instance *pinst);
+
 /**
  * @brief open pcap_live device
  *
@@ -77,10 +93,6 @@ int pio_pcap_live_device_send(struct packet_io_device *pdev, uint32_t txq_id, st
 
 void pio_pcap_live_device_pkt_free(struct packet_io_device *pdev, uint32_t qid, struct packet **pkts, int nr_pkts);
 
-int pio_pcap_live_instance_create(struct packet_io_instance *pinst, int wrk_thread_num);
-
-void pio_pcap_live_instance_destroy(struct packet_io_instance *pinst);
-
 void *pio_pcap_live_device_buff_ctrlzone(struct packet *p);
 
 char *pio_pcap_live_device_buff_mtod(struct packet *p);
diff --git a/src/packet_io/test/gtest_packet_io.cpp b/src/packet_io/test/gtest_packet_io.cpp
index 31f3052..7bbe42f 100644
--- a/src/packet_io/test/gtest_packet_io.cpp
+++ b/src/packet_io/test/gtest_packet_io.cpp
@@ -4,13 +4,13 @@
 
 TEST(PACKET_IO_Test, packet_io_instance_create) {
 	struct packet_io_config ppio_config;
-	struct packet_io_instance *ppio_inst = packet_io_instance_create("stellar", PACKET_IO_RUN_MODE_PCAP_FILE, 2);
+	struct packet_io_instance *ppio_inst = packet_io_instance_create("stellar", PACKET_IO_RUN_MODE_PCAP_FILE);
   	EXPECT_NE(ppio_inst, nullptr);
 }
 
 TEST(PACKET_IO_Test, packet_io_open_device) {
 	struct packet_io_config ppio_config;
-	struct packet_io_instance *ppio_inst = packet_io_instance_create("stellar", PACKET_IO_RUN_MODE_PCAP_FILE, 2);
+	struct packet_io_instance *ppio_inst = packet_io_instance_create("stellar", PACKET_IO_RUN_MODE_PCAP_FILE);
   	EXPECT_EQ(packet_io_device_open(ppio_inst, nullptr, 1, 1), nullptr);
 }