From 34a081be8e14b7ada70e069b65b05d54db4af497 Mon Sep 17 00:00:00 2001 From: Gerrit Renker Date: Thu, 4 Sep 2008 07:30:19 +0200 Subject: 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 --- net/dccp/ccids/ccid3.c | 38 ++++++++----------------------------- net/dccp/ccids/ccid3.h | 4 ---- net/dccp/ccids/lib/packet_history.c | 10 ++++++++++ net/dccp/ccids/lib/packet_history.h | 16 ++++++++++++++++ net/dccp/proto.c | 2 +- 5 files changed, 35 insertions(+), 35 deletions(-) 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 @@ static void ccid3_hc_rx_send_feedback(struct sock *sk, * 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 @@ static void ccid3_hc_rx_send_feedback(struct sock *sk, 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 @@ static void ccid3_hc_rx_send_feedback(struct sock *sk, 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 int ccid3_hc_rx_insert_options(struct sock *sk, struct sk_buff *skb) 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 @@ static u32 ccid3_first_li(struct sock *sk) } 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 @@ static u32 ccid3_first_li(struct sock *sk) 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 @@ static void ccid3_hc_rx_packet_recv(struct sock *sk, struct sk_buff *skb) 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 */ diff --git a/net/dccp/ccids/ccid3.h b/net/dccp/ccids/ccid3.h index 1773a8d..0c4fadd 100644 --- a/net/dccp/ccids/ccid3.h +++ b/net/dccp/ccids/ccid3.h @@ -124,25 +124,21 @@ enum ccid3_hc_rx_states { * * @last_counter - Tracks window counter (RFC 4342, 8.1) * @state - Receiver state, one of %ccid3_hc_rx_states - * @bytes_recv - Total sum of DCCP payload bytes * @x_recv - Receiver estimate of send rate (RFC 3448, sec. 4.3) * @rtt - Receiver estimate of RTT * @tstamp_last_feedback - Time at which last feedback was sent * @hist - Packet history (loss detection + RTT sampling) * @li_hist - Loss Interval database - * @s - Received packet size in bytes * @p_inverse - Inverse of Loss Event Rate (RFC 4342, sec. 8.5) */ struct ccid3_hc_rx_sock { u8 last_counter:4; enum ccid3_hc_rx_states state:8; - u32 bytes_recv; u32 x_recv; u32 rtt; ktime_t tstamp_last_feedback; struct tfrc_rx_hist hist; struct tfrc_loss_hist li_hist; - u16 s; #define p_inverse li_hist.i_mean }; diff --git a/net/dccp/ccids/lib/packet_history.c b/net/dccp/ccids/lib/packet_history.c index 8ea9690..ee34b45 100644 --- a/net/dccp/ccids/lib/packet_history.c +++ b/net/dccp/ccids/lib/packet_history.c @@ -352,6 +352,16 @@ int tfrc_rx_handle_loss(struct tfrc_rx_hist *h, __three_after_loss(h); } + /* + * Update moving-average of `s' and the sum of received payload bytes. + */ + if (dccp_data_packet(skb)) { + const u32 payload = skb->len - dccp_hdr(skb)->dccph_doff * 4; + + h->packet_size = tfrc_ewma(h->packet_size, payload, 9); + h->bytes_recvd += payload; + } + /* RFC 3448, 6.1: update I_0, whose growth implies p <= p_prev */ if (!is_new_loss) tfrc_lh_update_i_mean(lh, skb); diff --git a/net/dccp/ccids/lib/packet_history.h b/net/dccp/ccids/lib/packet_history.h index e9d8097..b7c87a1 100644 --- a/net/dccp/ccids/lib/packet_history.h +++ b/net/dccp/ccids/lib/packet_history.h @@ -91,12 +91,16 @@ struct tfrc_rx_hist_entry { * @loss_count: Number of entries in circular history * @loss_start: Movable index (for loss detection) * @rtt_sample_prev: Used during RTT sampling, points to candidate entry + * @packet_size: Packet size in bytes (as per RFC 3448, 3.1) + * @bytes_recvd: Number of bytes received since last sending feedback */ struct tfrc_rx_hist { struct tfrc_rx_hist_entry *ring[TFRC_NDUPACK + 1]; u8 loss_count:2, loss_start:2; #define rtt_sample_prev loss_start + u32 packet_size, + bytes_recvd; }; /** @@ -140,6 +144,18 @@ static inline bool tfrc_rx_hist_loss_pending(const struct tfrc_rx_hist *h) return h->loss_count > 0; } +/* + * Accessor functions to retrieve parameters sampled by the RX history + */ +static inline u32 tfrc_rx_hist_packet_size(const struct tfrc_rx_hist *h) +{ + if (h->packet_size == 0) { + DCCP_WARN("No sample for s, using fallback\n"); + return TCP_MIN_RCVMSS; + } + return h->packet_size; +} + extern void tfrc_rx_hist_add_packet(struct tfrc_rx_hist *h, const struct sk_buff *skb, const u64 ndp); diff --git a/net/dccp/proto.c b/net/dccp/proto.c index a3caa11..ecf3be9 100644 --- a/net/dccp/proto.c +++ b/net/dccp/proto.c @@ -185,7 +185,7 @@ int dccp_init_sock(struct sock *sk, const __u8 ctl_sock_initialized) sk->sk_state = DCCP_CLOSED; sk->sk_write_space = dccp_write_space; icsk->icsk_sync_mss = dccp_sync_mss; - dp->dccps_mss_cache = 536; + dp->dccps_mss_cache = TCP_MIN_RCVMSS; dp->dccps_rate_last = jiffies; dp->dccps_role = DCCP_ROLE_UNDEFINED; dp->dccps_service = DCCP_SERVICE_CODE_IS_ABSENT; -- cgit v1.1