From mboxrd@z Thu Jan 1 00:00:00 1970 From: Gerrit Renker Date: Sat, 27 Oct 2007 11:34:37 +0000 Subject: [PATCH 6/6]: Larger initial windows also for CCID2 Message-Id: <200710271234.37402@strip-the-willow> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: dccp@vger.kernel.org [CCID2]: Larger initial windows also for CCID2 RFC 4341, sec. 5 states that "The cwnd parameter is initialized to at most four packets for new connections, following the rules from [RFC3390]", which is implemented by this patch. Signed-off-by: Gerrit Renker --- net/dccp/ccids/ccid2.c | 20 +++++++++++++++----- 1 file changed, 15 insertions(+), 5 deletions(-) --- a/net/dccp/ccids/ccid2.c +++ b/net/dccp/ccids/ccid2.c @@ -741,15 +741,25 @@ static void ccid2_hc_tx_packet_recv(stru static int ccid2_hc_tx_init(struct ccid *ccid, struct sock *sk) { struct ccid2_hc_tx_sock *hctx = ccid_priv(ccid); + struct dccp_sock *dp = dccp_sk(sk); + u32 max_ratio; - ccid2_change_cwnd(hctx, 1); - /* Initialize ssthresh to infinity. This means that we will exit the - * initial slow-start after the first packet loss. This is what we - * want. - */ + /* RFC 4341, 5: initialise ssthresh to arbitrarily high (max) value */ hctx->ccid2hctx_ssthresh = ~0; hctx->ccid2hctx_numdupack = 3; + /* + * RFC 4341, 5: "The cwnd parameter is initialized to at most four + * packets for new connections, following the rules from [RFC3390]". + * We need to convert the bytes of RFC3390 into the packets of RFC 4341. + */ + hctx->ccid2hctx_cwnd = min(4U, max(2U, 4380U / dp->dccps_mss_cache)); + + /* Make sure that Ack Ratio is enabled and within bounds. */ + max_ratio = DIV_ROUND_UP(hctx->ccid2hctx_cwnd, 2); + if (dp->dccps_l_ack_ratio = 0 || dp->dccps_l_ack_ratio > max_ratio) + dp->dccps_l_ack_ratio = max_ratio; + /* XXX init ~ to window size... */ if (ccid2_hc_tx_alloc_seq(hctx)) return -ENOMEM;