Judge loss by arrival order and a deadline, one tx ring per stream

sock.go

@@ -16,9 +16,12 @@ type mmsghdr struct {
 func htons(v uint16) uint16 { return v<<8 | v>>8 }
 
 // Set through the FORCE options alone, since the plain ones are clamped to
-// wmem_max and rmem_max and would quietly leave a fraction of this.
+// wmem_max and rmem_max and would quietly leave a fraction of this. The send
+// buffer is sized past the tx ring's worth of in-flight truesize, so the ring
+// is what bounds the queue and a feeder pause has the full ring's slack
+// before the wire runs dry.
 const (
-	sndbufBytes = 8 << 20
+	sndbufBytes = 64 << 20
 	rcvbufBytes = 64 << 20
 )