: Make UDP wait for 64k of free buffer before telling select/poll there is space to send.

diff -u -r -N -X /home/greear/exclude.list linux/include/net/sock.h linux.dev/include/net/sock.h
@@ -1230,7 +1230,16 @@
  */
 static inline int sock_writeable(struct sock *sk)
 {
- return sock_wspace(sk) >= SOCK_MIN_WRITE_SPACE;
+   /* The goal is to only signal writable when there is at least 64k of buffer space
+    * when your send buffers are 128k or bigger.  The reason is that otherwise
+    * you get many failed UDP sends when you run > SOCK_MIN_WRITE_SPACE sized packets
+    * at extreme speed (ie faster than your network can keep up).  This change is
+    * designed to make select/poll wait untill you can actually be assured of sending
+    * the UDP packet at least into the kernel buffers w/out dropping it.
+    * This puts us more in line with sock_dev_write_space in core/sock.c too. --Ben
+    */
+   return sock_wspace(sk) >= max(SOCK_MIN_WRITE_SPACE,
+                                 min((unsigned int)(0xFFFF), sk->sndbuf >> 1));
 }
 
 static inline int gfp_any(void)