diff options
| -rw-r--r-- | net/dccp/ccids/ccid3.c | 64 | ||||
| -rw-r--r-- | net/dccp/ccids/lib/packet_history.c | 30 | ||||
| -rw-r--r-- | net/dccp/ccids/lib/packet_history.h | 13 |
3 files changed, 66 insertions, 41 deletions
diff --git a/net/dccp/ccids/ccid3.c b/net/dccp/ccids/ccid3.c index 8e64d9665a2..f2f9514dbad 100644 --- a/net/dccp/ccids/ccid3.c +++ b/net/dccp/ccids/ccid3.c @@ -533,9 +533,6 @@ static void ccid3_hc_rx_send_feedback(struct sock *sk, enum ccid3_fback_type fbtype) { struct ccid3_hc_rx_sock *hcrx = ccid3_hc_rx_sk(sk); - struct dccp_sock *dp = dccp_sk(sk); - ktime_t now = ktime_get_real(); - s64 delta = 0; switch (fbtype) { case CCID3_FBACK_INITIAL: @@ -565,42 +562,33 @@ static void ccid3_hc_rx_send_feedback(struct sock *sk, /* * When parameters change (new loss or p > p_prev), we do not * have a reliable estimate for R_m of [RFC 3448, 6.2] and so - * need to reuse the previous value of X_recv. However, when - * X_recv was 0 (due to early loss), this would kill X down to - * s/t_mbi (i.e. one packet in 64 seconds). - * To avoid such drastic reduction, we approximate X_recv as - * the number of bytes since last feedback. - * This is a safe fallback, since X is bounded above by X_calc. + * always check whether at least RTT time units were covered. */ - if (hcrx->x_recv > 0) - break; - /* fall through */ + hcrx->x_recv = tfrc_rx_hist_x_recv(&hcrx->hist, hcrx->x_recv); + break; case CCID3_FBACK_PERIODIC: /* - * FIXME: check if delta is less than or equal to 1 RTT using - * the receiver RTT sample. This is described in Errata 610/611 - * of RFC 4342 which reference section 6.2 of RFC 3448. + * Step (2) of rfc3448bis-06, 6.2: + * - if no data packets have been received, just restart timer + * - if data packets have been received, re-compute X_recv */ - delta = ktime_us_delta(now, hcrx->tstamp_last_feedback); - if (delta <= 0) - DCCP_BUG("delta (%ld) <= 0", (long)delta); - else - hcrx->x_recv = scaled_div32(hcrx->hist.bytes_recvd, delta); + if (hcrx->hist.bytes_recvd == 0) + goto prepare_for_next_time; + hcrx->x_recv = tfrc_rx_hist_x_recv(&hcrx->hist, hcrx->x_recv); break; default: return; } - ccid3_pr_debug("Interval %ldusec, X_recv=%u, 1/p=%u\n", - (long)delta, hcrx->x_recv, hcrx->p_inverse); + ccid3_pr_debug("X_recv=%u, 1/p=%u\n", hcrx->x_recv, hcrx->p_inverse); - hcrx->tstamp_last_feedback = now; - hcrx->last_counter = dccp_hdr(skb)->dccph_ccval; - hcrx->hist.bytes_recvd = 0; - hcrx->feedback = fbtype; - - dp->dccps_hc_rx_insert_options = 1; + dccp_sk(sk)->dccps_hc_rx_insert_options = 1; dccp_send_ack(sk); + +prepare_for_next_time: + tfrc_rx_hist_restart_byte_counter(&hcrx->hist); + hcrx->last_counter = dccp_hdr(skb)->dccph_ccval; + hcrx->feedback = fbtype; } static int ccid3_hc_rx_insert_options(struct sock *sk, struct sk_buff *skb) @@ -639,7 +627,7 @@ static u32 ccid3_first_li(struct sock *sk) { struct ccid3_hc_rx_sock *hcrx = ccid3_hc_rx_sk(sk); u32 s = tfrc_rx_hist_packet_size(&hcrx->hist), - rtt = tfrc_rx_hist_rtt(&hcrx->hist), x_recv, p, delta; + rtt = tfrc_rx_hist_rtt(&hcrx->hist), x_recv, p; u64 fval; /* @@ -650,16 +638,9 @@ static u32 ccid3_first_li(struct sock *sk) if (unlikely(hcrx->feedback == CCID3_FBACK_NONE)) return 5; - delta = ktime_to_us(net_timedelta(hcrx->tstamp_last_feedback)); - 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) { - DCCP_BUG("stored value of X_recv is zero"); - return ~0U; - } - x_recv = hcrx->x_recv; - } + x_recv = tfrc_rx_hist_x_recv(&hcrx->hist, hcrx->x_recv); + if (x_recv == 0) + goto failed; fval = scaled_div32(scaled_div(s, rtt), x_recv); p = tfrc_calc_x_reverse_lookup(fval); @@ -667,7 +648,10 @@ static u32 ccid3_first_li(struct sock *sk) ccid3_pr_debug("%s(%p), receive rate=%u bytes/s, implied " "loss rate=%u\n", dccp_role(sk), sk, x_recv, p); - return p == 0 ? ~0U : scaled_div(1, p); + if (p > 0) + return scaled_div(1, p); +failed: + return UINT_MAX; } static void ccid3_hc_rx_packet_recv(struct sock *sk, struct sk_buff *skb) diff --git a/net/dccp/ccids/lib/packet_history.c b/net/dccp/ccids/lib/packet_history.c index 5c4ded1cf42..547ad098ea6 100644 --- a/net/dccp/ccids/lib/packet_history.c +++ b/net/dccp/ccids/lib/packet_history.c @@ -385,6 +385,36 @@ int tfrc_rx_handle_loss(struct tfrc_rx_hist *h, } EXPORT_SYMBOL_GPL(tfrc_rx_handle_loss); +/* Compute the sending rate X_recv measured between feedback intervals */ +u32 tfrc_rx_hist_x_recv(struct tfrc_rx_hist *h, const u32 last_x_recv) +{ + u64 bytes = h->bytes_recvd, last_rtt = h->rtt_estimate; + s64 delta = ktime_to_us(net_timedelta(h->bytes_start)); + + WARN_ON(delta <= 0); + /* + * Ensure that the sampling interval for X_recv is at least one RTT, + * by extending the sampling interval backwards in time, over the last + * R_(m-1) seconds, as per rfc3448bis-06, 6.2. + * To reduce noise (e.g. when the RTT changes often), this is only + * done when delta is smaller than RTT/2. + */ + if (last_x_recv > 0 && delta < last_rtt/2) { + tfrc_pr_debug("delta < RTT ==> %ld us < %u us\n", + (long)delta, (unsigned)last_rtt); + + delta = (bytes ? delta : 0) + last_rtt; + bytes += div_u64((u64)last_x_recv * last_rtt, USEC_PER_SEC); + } + + if (unlikely(bytes == 0)) { + DCCP_WARN("X_recv == 0, using old value of %u\n", last_x_recv); + return last_x_recv; + } + return scaled_div32(bytes, delta); +} +EXPORT_SYMBOL_GPL(tfrc_rx_hist_x_recv); + void tfrc_rx_hist_purge(struct tfrc_rx_hist *h) { int i; diff --git a/net/dccp/ccids/lib/packet_history.h b/net/dccp/ccids/lib/packet_history.h index ba5832bbc34..6552be63cb0 100644 --- a/net/dccp/ccids/lib/packet_history.h +++ b/net/dccp/ccids/lib/packet_history.h @@ -93,7 +93,8 @@ struct tfrc_rx_hist_entry { * @rtt_sample_prev: Used during RTT sampling, points to candidate entry * @rtt_estimate: Receiver RTT estimate * @packet_size: Packet size in bytes (as per RFC 3448, 3.1) - * @bytes_recvd: Number of bytes received since last sending feedback + * @bytes_recvd: Number of bytes received since @bytes_start + * @bytes_start: Start time for counting @bytes_recvd */ struct tfrc_rx_hist { struct tfrc_rx_hist_entry *ring[TFRC_NDUPACK + 1]; @@ -105,6 +106,7 @@ struct tfrc_rx_hist { /* Receiver sampling of application payload lengths */ u32 packet_size, bytes_recvd; + ktime_t bytes_start; }; /** @@ -169,6 +171,15 @@ static inline u32 tfrc_rx_hist_rtt(const struct tfrc_rx_hist *h) return h->rtt_estimate; } +static inline void tfrc_rx_hist_restart_byte_counter(struct tfrc_rx_hist *h) +{ + h->bytes_recvd = 0; + h->bytes_start = ktime_get_real(); +} + +extern u32 tfrc_rx_hist_x_recv(struct tfrc_rx_hist *h, const u32 last_x_recv); + + extern void tfrc_rx_hist_add_packet(struct tfrc_rx_hist *h, const struct sk_buff *skb, const u64 ndp); |