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question on routine tcp_moderate_cwnd

To: netdev@xxxxxxxxxxx
Subject: question on routine tcp_moderate_cwnd
From: Brian Tierney <bltierney@xxxxxxx>
Date: Mon, 27 Jan 2003 13:20:15 -0800
Cc: Brian Tierney <bltierney@xxxxxxx>
Sender: netdev-bounce@xxxxxxxxxxx
Hi all:

Can someone explain what situation the routine tcp_moderate_cwnd is supposed to address?

Im finding that this code seems to be preventing TCP for achieving anything close to the available bandwidth on large BDP networks.

Thanks.

----------------

/* CWND moderation, preventing bursts due to too big ACKs
 * in dubious situations.
 */
static __inline__ void tcp_moderate_cwnd(struct tcp_opt *tp)
{
       u32 t = tcp_packets_in_flight(tp) + tcp_max_burst(tp);
        if (t < tp->snd_cwnd) {
                        tp->snd_cwnd = t;
                        WEB100_VAR_INC(tp, OtherReductions);
         }
        tp->snd_cwnd_stamp = tcp_time_stamp;
}



------------------------------------------------------------------------ -------------------
  Brian L. Tierney,   Lawrence Berkeley National Laboratory (LBNL)
  1 Cyclotron Rd.  MS: 50B-2239,  Berkeley, CA  94720
  tel: 510-486-7381    fax: 510-495-2998   efax:  240-332-4065
  bltierney@xxxxxxx   http://www-didc.lbl.gov/~tierney
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