lwip: Improve UDP buffering and thread priority

lib/net/nforceif/include/arch/sys_arch.h

@@ -73,7 +73,16 @@ typedef struct {
 /* let sys.h use binary semaphores for mutexes */
 #define LWIP_COMPAT_MUTEX 1
 
-#define SYS_MBOX_SIZE 128
+/**
+ * @brief Fixed mailbox capacity used by the nxdk lwIP sys_arch backend.
+ *
+ * This port backs every lwIP mailbox with a statically sized ring rather than
+ * honoring per-mailbox size requests. This larger shared depth absorbs
+ * transient backlog from short UDP bursts, especially through xemu user-mode
+ * NAT. This value is capped at 255 because lwIP's sys_sem_new() API only
+ * accepts an 8-bit initial semaphore count.
+ */
+#define SYS_MBOX_SIZE 255
 
 typedef struct {
     volatile int first, last;

lib/net/nforceif/include/lwipopts.h

@@ -43,6 +43,9 @@
 #define LWIP_IPV4 1
 #define LWIP_IPV6 1
 #define LWIP_IPV6_DHCP6 1
+#define LWIP_MDNS_RESPONDER 1
+#define LWIP_MDNS_SEARCH 1
+#define LWIP_NUM_NETIF_CLIENT_DATA LWIP_MDNS_RESPONDER
 #define LWIP_DEBUG 1
 #define LWIP_ERRNO_STDINCLUDE 1
 #define LWIP_COMPAT_MUTEX_ALLOWED
@@ -143,6 +146,15 @@
  */
 #define MEM_SIZE                        16000
 
+/**
+ * MEMP_NUM_PBUF: the number of pbuf reference structures that can be queued
+ * at once.
+ *
+ * This provides enough socket-layer bookkeeping entries for applications that
+ * receive short bursts of UDP packets.
+ */
+#define MEMP_NUM_PBUF                   128
+
 /*
    ---------------------------------
    ---------- ARP options ----------
@@ -280,7 +292,7 @@
 /**
  * LWIP_IGMP==1: Turn on IGMP module.
  */
-#define LWIP_IGMP                       0
+#define LWIP_IGMP                       1
 
 /*
    ----------------------------------
@@ -361,6 +373,14 @@
  */
 #define PBUF_LINK_HLEN                  16
 
+/**
+ * PBUF_POOL_SIZE: the number of packet buffers in the receive pool.
+ *
+ * This provides enough packet buffers for sustained UDP traffic while
+ * applications drain their receive sockets.
+ */
+#define PBUF_POOL_SIZE                  128
+
 /*
    ------------------------------------------------
    ---------- Network Interfaces options ----------
@@ -401,13 +421,29 @@
  */
 #define TCPIP_THREAD_STACKSIZE          4096
 
+/**
+ * TCPIP_THREAD_PRIO: The priority assigned to the main tcpip thread.
+ *
+ * Running the tcpip thread above the platform default helps it drain lwIP
+ * mailboxes before transient packet bursts turn into packet loss.
+ */
+#define TCPIP_THREAD_PRIO               2
+
 /**
  * DEFAULT_THREAD_STACKSIZE: The stack size used by any other lwIP thread.
  * The stack size value itself is platform-dependent, but is passed to
  * sys_thread_new() when the thread is created.
  */
 #define DEFAULT_THREAD_STACKSIZE        4096
 
+/**
+ * DEFAULT_THREAD_PRIO: The priority assigned to auxiliary lwIP threads.
+ *
+ * Auxiliary lwIP threads also run above the platform default so they keep up
+ * while the system is under application and network load.
+ */
+#define DEFAULT_THREAD_PRIO             1
+
 /*
    ----------------------------------------------
    ---------- Sequential layer options ----------
@@ -429,6 +465,22 @@
  */
 #define LWIP_SOCKET                     1
 
+/**
+ * LWIP_SO_RCVTIMEO==1: enable SO_RCVTIMEO support.
+ *
+ * Socket users can set receive timeouts instead of relying only on blocking
+ * receive calls.
+ */
+#define LWIP_SO_RCVTIMEO                1
+
+/**
+ * LWIP_SO_RCVBUF==1: enable SO_RCVBUF support.
+ *
+ * Socket users can tune receive buffer sizes for workloads with high-rate or
+ * bursty traffic.
+ */
+#define LWIP_SO_RCVBUF                  1
+
 /*
    ----------------------------------------
    ---------- Statistics options ----------

lib/net/nforceif/src/sys_arch.c

@@ -40,6 +40,7 @@
 #include <assert.h>
 #include <stdlib.h>
 
+#include <windows.h>
 #include <xboxkrnl/xboxkrnl.h>
 
 #if LWIP_DEBUG
@@ -68,9 +69,13 @@ sys_thread_t
 sys_thread_new(const char *name, lwip_thread_fn function, void *arg, int stacksize, int prio)
 {
     LWIP_UNUSED_ARG(name);
-    LWIP_UNUSED_ARG(prio);
 
-    return CreateThread(NULL, stacksize, (void *)function, arg, 0, NULL);
+    HANDLE thread = CreateThread(NULL, stacksize, (void *)function, arg, 0, NULL);
+    if ((thread != NULL) && (prio != 0)) {
+        SetThreadPriority(thread, prio);
+    }
+
+    return thread;
 }
 
 err_t

lib/net/nvnetdrv/nvnetdrv_lwip.c

@@ -25,7 +25,7 @@
 #define IFNAME0     'x'
 #define IFNAME1     'b'
 #ifndef RX_BUFF_CNT
-#define RX_BUFF_CNT (64)
+#define RX_BUFF_CNT (PBUF_POOL_SIZE)
 #endif
 
 #if RX_BUFF_CNT < TCP_WND / TCP_MSS
@@ -70,7 +70,13 @@ void rx_pbuf_free_callback (struct pbuf *p)
 void rx_callback (void *buffer, uint16_t length)
 {
     rx_pbuf_t *rx_pbuf = (rx_pbuf_t *)LWIP_MEMPOOL_ALLOC(RX_POOL);
-    LWIP_ASSERT("RX_POOL full\n", rx_pbuf != NULL);
+    if (rx_pbuf == NULL) {
+        LINK_STATS_INC(link.memerr);
+        LINK_STATS_INC(link.drop);
+        nvnetdrv_rx_release(buffer);
+        return;
+    }
+
     rx_pbuf->p.custom_free_function = rx_pbuf_free_callback;
     rx_pbuf->buff = buffer;
     struct pbuf *p = pbuf_alloced_custom(PBUF_RAW,
@@ -81,6 +87,8 @@ void rx_callback (void *buffer, uint16_t length)
                                          NVNET_RX_BUFF_LEN - ETH_PAD_SIZE);
 
     if (g_pnetif->input(p, g_pnetif) != ERR_OK) {
+        LINK_STATS_INC(link.memerr);
+        LINK_STATS_INC(link.drop);
         pbuf_free(p);
     }
 }