samples: net: zperf: Add loopback overlay

This is useful to profile networking stack using loopback interface, a
TX only option is also added but disabled by default.

Signed-off-by: Krishna T <[email protected]>

Author: Krishna T

samples/net/zperf/overlay-loopback.conf

@@ -0,0 +1,12 @@
+CONFIG_NET_DRIVERS=y
+CONFIG_NET_LOOPBACK=y
+CONFIG_NET_LOOPBACK_MTU=1100
+# Enable for testing TX only
+CONFIG_NET_LOOPBACK_SIMULATE_PACKET_DROP=y
+
+CONFIG_NET_BUF_DATA_SIZE=1100
+# Optimized networking settings for performance
+CONFIG_NET_PKT_RX_COUNT=32
+CONFIG_NET_PKT_TX_COUNT=48
+CONFIG_NET_BUF_RX_COUNT=32
+CONFIG_NET_BUF_TX_COUNT=96

samples/net/zperf/src/main.c

@@ -11,6 +11,9 @@
 #include <zephyr/usb/usb_device.h>
 #include <zephyr/net/net_config.h>
 
+#ifdef CONFIG_NET_LOOPBACK_SIMULATE_PACKET_DROP
+#include <zephyr/net/loopback.h>
+#endif
 void main(void)
 {
 #if defined(CONFIG_USB_DEVICE_STACK)
@@ -23,4 +26,7 @@ void main(void)
 
 	(void)net_config_init_app(NULL, "Initializing network");
 #endif /* CONFIG_USB_DEVICE_STACK */
+#ifdef CONFIG_NET_LOOPBACK_SIMULATE_PACKET_DROP
+	loopback_set_packet_drop_ratio(1);
+#endif
 }