dccp tfrc: Let dccp_tfrc_lib do the sampling work
This migrates more TFRC-related code into the dccp_tfrc_lib:
* sampling of the packet size `s' (which is only needed until the first
loss interval is computed (ccid3_first_li));
* updating the byte-counter `bytes_recvd' in between sending feedbacks.
The result is a better separation of CCID-3 specific and TFRC specific
code, which aids future integration with ECN and e.g. CCID-4.
Further changes:
----------------
* replaced magic number of 536 with equivalent constant TCP_MIN_RCVMSS;
(this constant is also used when no estimate for `s' is available).
Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
diff --git a/net/dccp/ccids/ccid3.c b/net/dccp/ccids/ccid3.c
index 50dac01..8744590 100644
--- a/net/dccp/ccids/ccid3.c
+++ b/net/dccp/ccids/ccid3.c
@@ -590,12 +590,9 @@
* would bring X down to s/t_mbi. That is why we return
* X_recv according to rfc3448bis-06 for the moment.
*/
- u32 rtt = hcrx->rtt ? : DCCP_FALLBACK_RTT, s = hcrx->s;
+ u32 rtt = hcrx->rtt ? : DCCP_FALLBACK_RTT,
+ s = tfrc_rx_hist_packet_size(&hcrx->hist);
- if (s == 0) {
- DCCP_WARN("No sample for s, using fallback\n");
- s = TCP_MIN_RCVMSS;
- }
hcrx->x_recv = scaled_div32(s, 2 * rtt);
break;
}
@@ -617,7 +614,7 @@
if (delta <= 0)
DCCP_BUG("delta (%ld) <= 0", (long)delta);
else
- hcrx->x_recv = scaled_div32(hcrx->bytes_recv, delta);
+ hcrx->x_recv = scaled_div32(hcrx->hist.bytes_recvd, delta);
break;
default:
return;
@@ -628,7 +625,7 @@
hcrx->tstamp_last_feedback = now;
hcrx->last_counter = dccp_hdr(skb)->dccph_ccval;
- hcrx->bytes_recv = 0;
+ hcrx->hist.bytes_recvd = 0;
dp->dccps_hc_rx_insert_options = 1;
dccp_send_ack(sk);
@@ -669,7 +666,8 @@
static u32 ccid3_first_li(struct sock *sk)
{
struct ccid3_hc_rx_sock *hcrx = ccid3_hc_rx_sk(sk);
- u32 x_recv, p, delta;
+ u32 x_recv, p, delta,
+ s = tfrc_rx_hist_packet_size(&hcrx->hist);
u64 fval;
/*
@@ -686,7 +684,7 @@
}
delta = ktime_to_us(net_timedelta(hcrx->tstamp_last_feedback));
- x_recv = scaled_div32(hcrx->bytes_recv, delta);
+ x_recv = scaled_div32(hcrx->hist.bytes_recvd, delta);
if (x_recv == 0) { /* would also trigger divide-by-zero */
DCCP_WARN("X_recv==0\n");
if (hcrx->x_recv == 0) {
@@ -696,8 +694,7 @@
x_recv = hcrx->x_recv;
}
- fval = scaled_div(hcrx->s, hcrx->rtt);
- fval = scaled_div32(fval, x_recv);
+ fval = scaled_div32(scaled_div(s, hcrx->rtt), x_recv);
p = tfrc_calc_x_reverse_lookup(fval);
ccid3_pr_debug("%s(%p), receive rate=%u bytes/s, implied "
@@ -724,31 +721,12 @@
if (unlikely(hcrx->state == TFRC_RSTATE_NO_DATA)) {
if (is_data_packet) {
- const u32 payload = skb->len - dccp_hdr(skb)->dccph_doff * 4;
do_feedback = CCID3_FBACK_INITIAL;
ccid3_hc_rx_set_state(sk, TFRC_RSTATE_DATA);
- hcrx->s = payload;
- /*
- * Not necessary to update bytes_recv here,
- * since X_recv = 0 for the first feedback packet (cf.
- * RFC 3448, 6.3) -- gerrit
- */
}
goto update_records;
}
- if (tfrc_rx_hist_duplicate(&hcrx->hist, skb))
- return; /* done receiving */
-
- if (is_data_packet) {
- const u32 payload = skb->len - dccp_hdr(skb)->dccph_doff * 4;
- /*
- * Update moving-average of s and the sum of received payload bytes
- */
- hcrx->s = tfrc_ewma(hcrx->s, payload, 9);
- hcrx->bytes_recv += payload;
- }
-
if (tfrc_rx_hist_loss_pending(&hcrx->hist))
return; /* done receiving */