[TCP] Westwood: bandwidth filter startup

The bandwidth estimate filter is now initialized with the first
sample in order to have better performances in the case of small
file transfers.

Signed-off-by: Luca De Cicco <ldecicco@gmail.com>
Signed-off-by: Stephen Hemminger <shemminger@dxpl.pdx.osdl.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/ipv4/tcp_westwood.c b/net/ipv4/tcp_westwood.c
index 12a2cd976e3a06b33edfe08e4d749ac309027506..edf2ee19a8ba76c6759d7758cd91b132a97ef958 100644 (file)
--- a/net/ipv4/tcp_westwood.c
+++ b/net/ipv4/tcp_westwood.c
@@ -82,10 +82,16 @@ static inline u32 westwood_do_filter(u32 a, u32 b)
        return (((7 * a) + b) >> 3);
 }
 
-static inline void westwood_filter(struct westwood *w, u32 delta)
+static void westwood_filter(struct westwood *w, u32 delta)
 {
-       w->bw_ns_est = westwood_do_filter(w->bw_ns_est, w->bk / delta);
-       w->bw_est = westwood_do_filter(w->bw_est, w->bw_ns_est);
+       /* If the filter is empty fill it with the first sample of bandwidth  */
+       if (w->bw_ns_est == 0 && w->bw_est == 0) {
+               w->bw_ns_est = w->bk / delta;
+               w->bw_est = w->bw_ns_est;
+       } else {
+               w->bw_ns_est = westwood_do_filter(w->bw_ns_est, w->bk / delta);
+               w->bw_est = westwood_do_filter(w->bw_est, w->bw_ns_est);
+       }
 }
 
 /*