> -----Original Message-----
> From: Thomas Kho [mailto:[EMAIL PROTECTED]
> Sent: Monday, May 29, 2006 6:22 AM
> To: #ZHOU BIN#
> Cc: [EMAIL PROTECTED]; netdev@vger.kernel.org
> Subject: Re: [PATCH] TCP Veno module for kernel 2.6.16.13
> 
> 
> On 5/24/06, #ZHOU BIN# <[EMAIL PROTECTED]> wrote:
> > +       u16     cntRTT;         /* # of RTTs measured 
> within last RTT */
> 
> > +       /* veno->cntRTT = 0; */
> 
> It looks like this counter is never initialized

Yes, I agree. It should be done at tcp_veno_init(). I've corrected it.  Also 
avoid the mix caps this time, according to the suggestion from J. Morris. 
Following is the new patch.

Thank you all for the comments.


Sign-off-by: Bin Zhou <[EMAIL PROTECTED]>, Cheng Peng Fu <[EMAIL PROTECTED]>

diff -urN linux-2.6.16.13/net/ipv4/Kconfig 
linux-2.6.16.13-veno-1/net/ipv4/Kconfig
--- linux-2.6.16.13/net/ipv4/Kconfig    2006-05-03 05:38:44.000000000 +0800
+++ linux-2.6.16.13-veno-1/net/ipv4/Kconfig     2006-05-20 16:16:44.712926200 
+0800
@@ -521,6 +521,18 @@
        window. TCP Vegas should provide less packet loss, but it is
        not as aggressive as TCP Reno.
 
+config TCP_CONG_VENO
+       tristate "TCP Veno"
+       depends on EXPERIMENTAL
+       default n
+       ---help---
+       TCP Veno is a sender-side only enhancement of TCP to obtain better
+       throughput over wirless networks. TCP Veno makes use of state 
+       distinguishing to circumvent the difficult judgment of the packet loss 
type.
+       TCP Veno cuts down less congestion window in response to random loss
+       packets. 
+       See http://www.ntu.edu.sg/home5/ZHOU0022/papers/CPFu03a.pdf
+       
 config TCP_CONG_SCALABLE
        tristate "Scalable TCP"
        depends on EXPERIMENTAL
diff -urN linux-2.6.16.13/net/ipv4/Makefile 
linux-2.6.16.13-veno-1/net/ipv4/Makefile
--- linux-2.6.16.13/net/ipv4/Makefile   2006-05-03 05:38:44.000000000 +0800
+++ linux-2.6.16.13-veno-1/net/ipv4/Makefile    2006-05-20 15:57:45.308758200 
+0800
@@ -40,6 +40,7 @@
 obj-$(CONFIG_TCP_CONG_HYBLA) += tcp_hybla.o
 obj-$(CONFIG_TCP_CONG_HTCP) += tcp_htcp.o
 obj-$(CONFIG_TCP_CONG_VEGAS) += tcp_vegas.o
+obj-$(CONFIG_TCP_CONG_VENO) += tcp_veno.o
 obj-$(CONFIG_TCP_CONG_SCALABLE) += tcp_scalable.o
 
 obj-$(CONFIG_XFRM) += xfrm4_policy.o xfrm4_state.o xfrm4_input.o \
diff -urN linux-2.6.16.13/net/ipv4/tcp_veno.c 
linux-2.6.16.13-veno-1/net/ipv4/tcp_veno.c
--- linux-2.6.16.13/net/ipv4/tcp_veno.c 1970-01-01 08:00:00.000000000 +0800
+++ linux-2.6.16.13-veno-1/net/ipv4/tcp_veno.c  2006-05-29 11:10:04.368125900 
+0800
@@ -0,0 +1,253 @@
+/*
+ * TCP Veno congestion control
+ *
+ * This is based on the congestion detection/avoidance scheme described in
+ *    C. P. Fu, S. C. Liew.
+ *    "TCP Veno: TCP Enhancement for Transmission over Wireless Access 
Networks."
+ *    IEEE Journal on Selected Areas in Communication,
+ *    Feb. 2003.
+ *     See http://www.ntu.edu.sg/home5/ZHOU0022/papers/CPFu03a.pdf
+ */
+
+#include <linux/config.h>
+#include <linux/mm.h>
+#include <linux/module.h>
+#include <linux/skbuff.h>
+#include <linux/inet_diag.h>
+
+#include <net/tcp.h>
+
+/* Default values of the Veno variables, in fixed-point representation
+ * with V_PARAM_SHIFT bits to the right of the binary point.
+ */
+#define V_PARAM_SHIFT 1
+static int beta  = 3<<V_PARAM_SHIFT;
+
+
+/* Veno variables */
+struct veno {
+       u8      doing_veno_now;/* if true, do veno for this RTT */
+       u16     cntrtt;         /* # of RTTs measured */
+       u32     minrtt;         /* min of RTTs measured within last RTT (in 
usec) */
+       u32     basertt;        /* the min of all Veno RTT measurements seen 
(in usec) */
+       u32     inc;    /* decide whether to increase cwnd */
+       u32 diff;       /* calculate the diff rate */
+};
+
+/* There are several situations when we must "re-start" Veno:
+ *
+ *  o when a connection is established
+ *  o after an RTO
+ *  o after fast recovery
+ *  o when we send a packet and there is no outstanding
+ *    unacknowledged data (restarting an idle connection)
+ *
+ */
+static inline void veno_enable(struct sock *sk)
+{
+       struct veno *veno = inet_csk_ca(sk);
+
+       /* turn on Veno */
+       veno->doing_veno_now = 1;
+
+       veno->minrtt = 0x7fffffff;
+}
+
+static inline void veno_disable(struct sock *sk)
+{
+       struct veno *veno = inet_csk_ca(sk);
+
+       /* turn off Veno */
+       veno->doing_veno_now = 0;
+}
+
+static void tcp_veno_init(struct sock *sk)
+{
+       struct veno *veno = inet_csk_ca(sk);
+
+       veno->basertt = 0x7fffffff;
+       veno->inc = 1;
+       veno->cntrtt = 0;
+       veno_enable(sk);
+}
+
+/* Do RTT sampling needed for Veno. */
+static void tcp_veno_rtt_calc(struct sock *sk, u32 usrtt)
+{
+       struct veno *veno = inet_csk_ca(sk);
+       u32 vrtt = usrtt + 1; /* Never allow zero rtt or baseRTT */
+
+       /* Filter to find propagation delay: */
+       if (vrtt < veno->basertt)
+               veno->basertt = vrtt;
+
+       /* Find the min RTT during the last RTT to find
+        * the current prop. delay + queuing delay:
+        */
+       veno->minrtt = min(veno->minrtt, vrtt);
+       veno->cntrtt++;
+}
+
+static void tcp_veno_state(struct sock *sk, u8 ca_state)
+{
+
+       if (ca_state == TCP_CA_Open)
+               veno_enable(sk);
+       else
+               veno_disable(sk);
+}
+
+/*
+ * If the connection is idle and we are restarting,
+ * then we don't want to do any Veno calculations
+ * until we get fresh RTT samples.  So when we
+ * restart, we reset our Veno state to a clean
+ * state. After we get acks for this flight of
+ * packets, _then_ we can make Veno calculations
+ * again.
+ */
+static void tcp_veno_cwnd_event(struct sock *sk, enum tcp_ca_event event)
+{
+       if (event == CA_EVENT_CWND_RESTART ||
+           event == CA_EVENT_TX_START)
+               tcp_veno_init(sk);
+}
+
+static void tcp_veno_cong_avoid(struct sock *sk, u32 ack,
+                                u32 seq_rtt, u32 in_flight, int flag)
+{
+       struct tcp_sock *tp = tcp_sk(sk);
+       struct veno *veno = inet_csk_ca(sk); 
+
+       if (!veno->doing_veno_now)
+               return tcp_reno_cong_avoid(sk, ack, seq_rtt, in_flight, flag); 
+
+       /* limited by applications */
+       if (!tcp_is_cwnd_limited(sk, in_flight))
+               return;
+
+       /* We do the Veno calculations only if we got enough RTT samples */
+       if (veno->cntrtt <= 2) {
+               /* We don't have enough RTT samples to do the Veno
+                * calculation, so we'll behave like Reno.
+                */ 
+               tcp_reno_cong_avoid(sk, ack, seq_rtt, in_flight, flag);
+       } else {
+               u32 rtt, target_cwnd;
+
+               /* We have enough RTT samples, so, using the Veno
+                * algorithm, we determine the state of the network.
+                */
+
+               rtt = veno->minrtt;
+
+               target_cwnd = ((tp->snd_cwnd * veno->basertt)
+                              << V_PARAM_SHIFT) / rtt;
+               
+               veno->diff = (tp->snd_cwnd << V_PARAM_SHIFT) - target_cwnd;
+               
+               if (tp->snd_cwnd <= tp->snd_ssthresh) {
+                       /* Slow start.  */ 
+                       tcp_slow_start(tp);
+               } 
+               else if (sysctl_tcp_abc) {
+                       /* RFC3465: Apppriate Byte Count
+                       * increase once for each full cwnd acked.
+                       * Veno has no idear about it so far, so we keep
+                       * it as Reno.
+                       */
+                       if (tp->bytes_acked >= tp->snd_cwnd*tp->mss_cache) {
+                               tp->bytes_acked -= tp->snd_cwnd*tp->mss_cache;
+                               if (tp->snd_cwnd < tp->snd_cwnd_clamp)
+                                       tp->snd_cwnd++;
+                       }
+               }else {
+                       /* Congestion avoidance. */ 
+                       if (veno->diff < beta) {
+                               /* In the "non-congestive state", increase cwnd
+                                *  every rtt.
+                                */ 
+                               if (tp->snd_cwnd_cnt >= tp->snd_cwnd) {
+                                       if (tp->snd_cwnd < tp->snd_cwnd_clamp)
+                                               tp->snd_cwnd++;
+                                       tp->snd_cwnd_cnt = 0;
+                               } else
+                                       tp->snd_cwnd_cnt++;
+                       } else {
+                               /* In the "congestive state", increase cwnd
+                                * every other rtt.
+                                */ 
+                                       if (tp->snd_cwnd_cnt >= tp->snd_cwnd) {
+                                               if (veno->inc && tp->snd_cwnd < 
tp->snd_cwnd_clamp) {
+                                               tp->snd_cwnd++;
+                                               veno->inc = 0;
+                       }
+                                       else
+                                               veno->inc = 1;
+                                               tp->snd_cwnd_cnt = 0;
+                                       } else
+                                               tp->snd_cwnd_cnt++;
+                       }
+                       
+               }
+               if (tp->snd_cwnd < 2)
+                       tp->snd_cwnd = 2;
+               else if (tp->snd_cwnd > tp->snd_cwnd_clamp)
+                       tp->snd_cwnd = tp->snd_cwnd_clamp;
+       }
+               /* Wipe the state clean for the next RTT. */
+       veno->minrtt = 0x7fffffff;
+       }
+
+/* Veno MD phase */
+u32 tcp_veno_ssthresh(struct sock *sk)
+{
+       const struct tcp_sock *tp = tcp_sk(sk);
+       struct veno *veno = inet_csk_ca(sk); 
+       if(veno->diff < beta) {
+               /* in "non-congestive state", cut cwnd by 1/5 */ 
+               return max(tp->snd_cwnd*4/5, 2U);
+       }else {
+               /* in "congestive state", cut cwnd by 1/2 */ 
+               return max(tp->snd_cwnd >> 1U, 2U);
+       }
+}
+
+u32 tcp_veno_min_cwnd(struct sock *sk)
+{
+       const struct tcp_sock *tp = tcp_sk(sk); 
+       return tp->snd_ssthresh;
+}
+
+
+static struct tcp_congestion_ops tcp_veno = {
+       .init           = tcp_veno_init,
+       .ssthresh       = tcp_veno_ssthresh,
+       .cong_avoid     = tcp_veno_cong_avoid,
+       .min_cwnd       = tcp_veno_min_cwnd,
+       .rtt_sample     = tcp_veno_rtt_calc,
+       .set_state      = tcp_veno_state, 
+       .cwnd_event     = tcp_veno_cwnd_event,
+
+       .owner          = THIS_MODULE,
+       .name           = "veno",
+};
+
+static int __init tcp_veno_register(void)
+{
+       BUG_ON(sizeof(struct veno) > ICSK_CA_PRIV_SIZE);
+       tcp_register_congestion_control(&tcp_veno);
+       return 0;
+}
+
+static void __exit tcp_veno_unregister(void)
+{
+       tcp_unregister_congestion_control(&tcp_veno);
+}
+
+module_init(tcp_veno_register);
+module_exit(tcp_veno_unregister);
+
+MODULE_AUTHOR("Bin Zhou, Cheng Peng Fu");
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("TCP Veno");
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