[CCID 3]: New RX History Step 4 - Integrate Receiver RTT sampling (part 3 of 3)
The previous patch introduced the new algorithm to perform receiver RTT sampling.
This patch integrates this new algorithm into CCID3.
This results in the following changes:
* Receiver does no longer send Timestamp option to sample the RTT.
=> This is for completeness, since the option is no longer used. If this
algorithm proves not so good, switching back to using timestamp options
requires to re-think the timestamp-based RTT estimation algorithm with
regard to the issues raised in RFC 1323 (and its erratum) for RTTM; meaning
in particular re-ordered packets and idle phases.
* The corresponding code in the receiver has been removed.
Signed-off-by: Gerrit Renker <gerrit@xxxxxxxxxxxxxx>
---
net/dccp/ccids/ccid3.c | 58 ++++++++++++++++---------------------------------
1 file changed, 19 insertions(+), 39 deletions(-)
--- a/net/dccp/ccids/ccid3.c
+++ b/net/dccp/ccids/ccid3.c
@@ -722,8 +722,7 @@ static int ccid3_hc_rx_insert_options(st
x_recv = htonl(hcrx->ccid3hcrx_x_recv);
pinv = htonl(hcrx->ccid3hcrx_pinv);
- if (dccp_insert_option_timestamp(sk, skb) ||
- dccp_insert_option(sk, skb, TFRC_OPT_LOSS_EVENT_RATE,
+ if (dccp_insert_option(sk, skb, TFRC_OPT_LOSS_EVENT_RATE,
&pinv, sizeof(pinv)) ||
dccp_insert_option(sk, skb, TFRC_OPT_RECEIVE_RATE,
&x_recv, sizeof(x_recv)))
@@ -887,44 +886,29 @@ detect_out:
static void ccid3_hc_rx_packet_recv(struct sock *sk, struct sk_buff *skb)
{
struct ccid3_hc_rx_sock *hcrx = ccid3_hc_rx_sk(sk);
- const struct dccp_options_received *opt_recv;
struct dccp_rx_hist_entry *packet;
struct timeval now;
- u32 p_prev, r_sample, rtt_prev;
- int loss, payload_size;
+ u32 p_prev, loss;
+ u32 sample, ndp = dccp_sk(sk)->dccps_options_received.dccpor_ndp,
+ payload_size = skb->len - dccp_hdr(skb)->dccph_doff * 4;
+ u8 is_data_packet = dccp_data_packet(skb), do_feedback = 0;
- opt_recv = &dccp_sk(sk)->dccps_options_received;
+ /*
+ * Handle data packets: RTT sampling and monitoring p
+ */
+ if (unlikely(!is_data_packet))
+ goto update_records;
- switch (DCCP_SKB_CB(skb)->dccpd_type) {
- case DCCP_PKT_ACK:
- if (hcrx->ccid3hcrx_state == TFRC_RSTATE_NO_DATA)
- return;
- case DCCP_PKT_DATAACK:
- if (opt_recv->dccpor_timestamp_echo == 0)
- break;
- rtt_prev = hcrx->ccid3hcrx_rtt;
- dccp_timestamp(sk, &now);
- r_sample = dccp_sample_rtt(sk, &now, NULL);
+ if (list_empty(&hcrx->ccid3hcrx_li_hist)) { /* no loss so far: p = 0 */
+
+ sample = tfrc_rx_sample_rtt(&hcrx->ccid3hcrx_hist, skb);
+ if (sample != 0)
+ hcrx->ccid3hcrx_rtt =
+ tfrc_ewma(hcrx->ccid3hcrx_rtt, sample, 9);
- if (hcrx->ccid3hcrx_state == TFRC_RSTATE_NO_DATA)
- hcrx->ccid3hcrx_rtt = r_sample;
- else
- hcrx->ccid3hcrx_rtt = (hcrx->ccid3hcrx_rtt * 9) / 10 +
- r_sample / 10;
-
- if (rtt_prev != hcrx->ccid3hcrx_rtt)
- ccid3_pr_debug("%s(%p), New RTT=%uus, elapsed time=%u\n",
- dccp_role(sk), sk, hcrx->ccid3hcrx_rtt,
- opt_recv->dccpor_elapsed_time);
- break;
- case DCCP_PKT_DATA:
- break;
- default: /* We're not interested in other packet types, move along */
- return;
}
- packet = dccp_rx_hist_entry_new(ccid3_rx_hist, sk, opt_recv->dccpor_ndp,
- skb, GFP_ATOMIC);
+ packet = dccp_rx_hist_entry_new(ccid3_rx_hist, sk, ndp, skb, GFP_ATOMIC);
if (unlikely(packet == NULL)) {
DCCP_WARN("%s(%p), Not enough mem to add rx packet "
"to history, consider it lost!\n", dccp_role(sk), sk);
@@ -933,10 +917,6 @@ static void ccid3_hc_rx_packet_recv(stru
loss = ccid3_hc_rx_detect_loss(sk, packet);
- if (DCCP_SKB_CB(skb)->dccpd_type == DCCP_PKT_ACK)
- return;
-
- payload_size = skb->len - dccp_hdr(skb)->dccph_doff * 4;
ccid3_hc_rx_update_s(hcrx, payload_size);
switch (hcrx->ccid3hcrx_state) {
@@ -969,8 +949,8 @@ static void ccid3_hc_rx_packet_recv(stru
return;
}
- /* Update highest received sequence number so far */
- tfrc_rx_hist_update(&hcrx->ccid3hcrx_hist, skb, opt_recv->dccpor_ndp);
+update_records:
+ tfrc_rx_hist_update(&hcrx->ccid3hcrx_hist, skb, ndp);
/* Dealing with packet loss */
ccid3_pr_debug("%s(%p, state=%s), data loss! Reacting...\n",
-
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