diff --git a/README.md b/README.md index 63a3d72..79351c8 100644 --- a/README.md +++ b/README.md @@ -21,6 +21,11 @@ sudo sysctl net.ipv4.tcp_congestion_control=roccet ``` ### Versions +- latest on master branch + - Improved min RTT probing + - Packet pacing + - Code refactor + - release-2026-06-12-v1 - Adds minimum RTT probing diff --git a/tcp_roccet.c b/tcp_roccet.c index 878a05e..803195f 100644 --- a/tcp_roccet.c +++ b/tcp_roccet.c @@ -68,10 +68,10 @@ #define ROCCET_NEXT_MIN_RTT_PROBE 5000 /* Parameters that are specific to the ROCCET-Algorithm */ -static int sr_rtt_upper_bound __read_mostly = 100; +static uint sr_rtt_upper_bound __read_mostly = 100; static int ack_rate_diff_ss __read_mostly = 10; -module_param(sr_rtt_upper_bound, int, 0644); +module_param(sr_rtt_upper_bound, uint, 0644); MODULE_PARM_DESC(sr_rtt_upper_bound, "ROCCET's upper bound for srRTT."); module_param(ack_rate_diff_ss, int, 0644); MODULE_PARM_DESC(ack_rate_diff_ss, @@ -107,6 +107,16 @@ static __always_inline void roccettcp_reset(struct roccettcp *ca) ca->curr_min_rtt = ~0U; ca->last_rtt = 0; ca->ece_received = false; + + ca->roccet_last_event_time_us = 0; + ca->ack_rate.last_rate = 0; + /* Initialize to current time to avoid overflow in ack rate calculation */ + ca->ack_rate.last_rate_time = jiffies_to_usecs(tcp_jiffies32); + ca->ack_rate.curr_rate = 0; + ca->ack_rate.cnt = 0; + + /* Start state is LAUNCH */ + ca->state = LAUNCH; } /* Return true if ROCCET is in min RTT probing. @@ -135,11 +145,11 @@ static __always_inline void update_min_rtt(struct sock *sk) /* Return difference between last and current ack rate. */ -static __always_inline int get_ack_rate_diff(struct roccettcp *ca) +static __always_inline s32 get_ack_rate_diff(struct roccettcp *ca) { if (ca->ack_rate.curr_rate < ca->ack_rate.last_rate) return 0; - return ca->ack_rate.curr_rate - ca->ack_rate.last_rate; + return (s32)(ca->ack_rate.curr_rate - ca->ack_rate.last_rate); } /* Update ack rate sampled by 100ms. @@ -147,13 +157,26 @@ static __always_inline int get_ack_rate_diff(struct roccettcp *ca) static __always_inline void update_ack_rate(struct sock *sk, u32 acked, u32 now) { struct roccettcp *ca = inet_csk_ca(sk); - u32 interval = USEC_PER_MSEC * 100; + s32 interval = USEC_PER_MSEC * 100; - if (after(now, ca->ack_rate.last_rate_time + interval)) { - ca->ack_rate.last_rate_time = now; - ca->ack_rate.last_rate = ca->ack_rate.curr_rate; - ca->ack_rate.curr_rate = ca->ack_rate.cnt; - ca->ack_rate.cnt = acked; // start counting for the new interval + s32 time_delta = (s32)(ca->ack_rate.last_rate_time - now); + const s32 idle_threshold = USEC_PER_SEC * 2; + + // Check if the time has arrived in the new interval + if (time_delta < -interval) { + // Check if the connection was idle for X seconds (e.g. no ACK for X seconds) + if (time_delta < -idle_threshold) { + // Reset ack counting as if a new connection was created + ca->ack_rate.last_rate = 0; + ca->ack_rate.last_rate_time = jiffies_to_usecs(tcp_jiffies32); + ca->ack_rate.curr_rate = 0; + ca->ack_rate.cnt = 0; + } else { + ca->ack_rate.last_rate_time = now; + ca->ack_rate.last_rate = ca->ack_rate.curr_rate; + ca->ack_rate.curr_rate = ca->ack_rate.cnt; + ca->ack_rate.cnt = acked; // start counting for the new interval + } } else { ca->ack_rate.cnt += acked; } @@ -189,8 +212,8 @@ static __always_inline void update_srrtt(struct sock *sk) * * 0 is a valid value for rrtt. */ - u32 rrtt = (100 * (ca->curr_rtt - ca->curr_min_rtt)) / - ca->curr_min_rtt; + u32 rrtt = div_u64(100 * (u64)(ca->curr_rtt - ca->curr_min_rtt), + ca->curr_min_rtt); // (1 - alpha) * srRTT + alpha * rRTT ca->curr_srrtt = ((100 - ROCCET_ALPHA_TIMES_100) * ca->curr_srrtt + @@ -209,11 +232,74 @@ static __always_inline void roccet_congestion_event(struct sock *sk, u32 now) ca->cnt = 100 * tcp_snd_cwnd(tp); ca->last_max_cwnd = tcp_snd_cwnd(tp); tcp_snd_cwnd_set(tp, min(tp->snd_cwnd_clamp, - max((tcp_snd_cwnd(tp) * beta) / - BICTCP_BETA_SCALE, 2U))); + max((tcp_snd_cwnd(tp) * beta) / + BICTCP_BETA_SCALE, 2U))); tp->snd_ssthresh = tcp_snd_cwnd(tp); } +/* Do minimum RTT probing. + */ +static __always_inline void roccet_min_rtt_probe(struct sock *sk, u32 now) +{ + struct tcp_sock *tp = tcp_sk(sk); + struct roccettcp *ca = inet_csk_ca(sk); + u32 interval, probe_cwnd; + + /* Do nothing if we are probing */ + if (before(now, ca->probe_min_rtt_until) && ca->probe_min_rtt_until > 0) + return; + + /* Start of min RTT probing*/ + if(ca->probe_min_rtt_until == 0){ + /* Probe 1*RTT or at least 200ms */ + interval = max(200 * USEC_PER_MSEC, ca->curr_rtt); + + /* This is to handle deep shared buffers with loss-based + * congestion control like CUBIC. If the the cwnd is not limited + * by the application but falsely detected (see ROCCET paper), + * we have to empty the pipe more. + * If the limit detection is correct this will cause no harm + * to the tcp flow because the cwnd is not fully utilized and + * we set the cwnd to its previous value after probing. + */ + probe_cwnd = max(tcp_snd_cwnd(tp) / 2, TCP_INIT_CWND); + if (!tcp_is_cwnd_limited(sk)) + probe_cwnd = max(tcp_snd_cwnd(tp) / 3, TCP_INIT_CWND); + + ca->probe_min_rtt_until = now + interval; + ca->cwnd_before_min_rtt_probe = tcp_snd_cwnd(tp); + + /* Half the cwnd to drain the buffer for probing. + * Set the ssthresh to the probing cwnd otherwise + * the TCP state machine is in slow start. + */ + tcp_snd_cwnd_set(tp, probe_cwnd); + tcp_sk(sk)->snd_ssthresh = tcp_snd_cwnd(tp); + + /* Reset current min RTT to allow probing for + * a new lower and higher minimum RTT. + */ + ca->curr_min_rtt = ~0U; + + /* Refill the pipe after probing. + * To this end we need the previous cwnd over the + * the probing interval. + */ + ca->refill_until = ca->probe_min_rtt_until + interval; + }else if(before(now, ca->refill_until)){ + /* Reset cwnd and refill the pipe. */ + if(ca->state != RTT_PROBE_REFILL){ + tcp_snd_cwnd_set(tp, ca->cwnd_before_min_rtt_probe); + tcp_sk(sk)->snd_ssthresh = tcp_snd_cwnd(tp); + ca->state = RTT_PROBE_REFILL; + } + }else{ + /* End min RTT probing phase. */ + ca->probe_min_rtt_until = 0; + ca->state = ORBITER; + } +} + static void roccettcp_init(struct sock *sk) { struct roccettcp *ca = inet_csk_ca(sk); @@ -223,33 +309,25 @@ static void roccettcp_init(struct sock *sk) if (initial_ssthresh) tcp_sk(sk)->snd_ssthresh = initial_ssthresh; - /* Initial roccet parameters */ - ca->roccet_last_event_time_us = 0; - ca->ack_rate.last_rate = 0; - ca->ack_rate.last_rate_time = 0; - ca->ack_rate.curr_rate = 0; - ca->ack_rate.cnt = 0; + cmpxchg(&sk->sk_pacing_status, SK_PACING_NONE, SK_PACING_NEEDED); + //WRITE_ONCE(sk->sk_pacing_rate, 0); } -static void roccettcp_cwnd_event(struct sock *sk, - enum tcp_ca_event event) +static void roccettcp_cwnd_event_tx_start(struct sock *sk) { - if (event == CA_EVENT_TX_START) { - struct roccettcp *ca = inet_csk_ca(sk); - u32 now = tcp_jiffies32; - s32 delta; + struct roccettcp *ca = inet_csk_ca(sk); + u32 now = tcp_jiffies32; + s32 delta; - delta = now - tcp_sk(sk)->lsndtime; + delta = now - tcp_sk(sk)->lsndtime; - /* We were application limited (idle) for a while. - * Shift epoch_start to keep cwnd growth to cubic curve. - */ - if (ca->epoch_start && delta > 0) { - ca->epoch_start += delta; - if (after(ca->epoch_start, now)) - ca->epoch_start = now; - } - return; + /* We were application limited (idle) for a while. + * Shift epoch_start to keep cwnd growth to cubic curve. + */ + if (ca->epoch_start && delta > 0) { + ca->epoch_start += delta; + if (after(ca->epoch_start, now)) + ca->epoch_start = now; } } @@ -412,7 +490,7 @@ tcp_friendliness: } static void roccettcp_cong_avoid(struct sock *sk, u32 ack, - u32 acked) + u32 acked) { struct tcp_sock *tp = tcp_sk(sk); struct roccettcp *ca = inet_csk_ca(sk); @@ -422,120 +500,137 @@ static void roccettcp_cong_avoid(struct sock *sk, u32 ack, u32 roccet_xj; u32 jitter; - if (after(ca->last_rtt, ca->curr_rtt)) - jitter = ca->last_rtt - ca->curr_rtt; - else - jitter = ca->curr_rtt - ca->last_rtt; - - /* Update roccet parameters */ - update_ack_rate(sk, acked, now); - update_min_rtt(sk); - update_srrtt(sk); - - /* do not increase the cwnd if in RTT probe */ - if (is_in_min_rtt_probing(ca, now)) - return; - - /* Probe for min RTT if the last min RTT update is - * ROCCET_NEXT_MIN_RTT_PROBE seconds ago. - */ - if (after(now, ca->next_min_rtt_probe)){ - ca->probe_min_rtt_until = now + min(200, 2 * ca->curr_rtt) * USEC_PER_MSEC; - ca->cwnd_before_min_rtt_probe = tcp_snd_cwnd(tp); - tcp_snd_cwnd_set(tp, max(tcp_snd_cwnd(tp) / 2, TCP_INIT_CWND)); - ca->curr_min_rtt = ~0U; - return; - } - - /* ROCCET drain. - * Do not increase the cwnd for 100ms after a roccet congestion event - * because the buffer is still not drained. - */ - if (now - ca->roccet_last_event_time_us <= 100 * USEC_PER_MSEC) - return; - - /* LAUNCH: Detect an exit point for tcp slow start + if(ca->state == LAUNCH){ + /* LAUNCH: Detect an exit point for tcp slow start * in networks with large buffers of multiple BDP * Like in cellular networks (5G, ...). * Or exit LAUNCH if cwnd is too large for application layer * data rate (tcp cwnd validation). */ + if ((ca->curr_srrtt > sr_rtt_upper_bound && + get_ack_rate_diff(ca) <= ack_rate_diff_ss) || + !tcp_is_cwnd_limited(sk)) { + ca->epoch_start = 0; - if ((tcp_in_slow_start(tp) && ca->curr_srrtt > sr_rtt_upper_bound && - get_ack_rate_diff(ca) <= ack_rate_diff_ss) || - (!tcp_is_cwnd_limited(sk) && tcp_in_slow_start(tp))) { - ca->epoch_start = 0; + /* Handle initial slow start. Here occur most bufferbloat */ + if (tp->snd_ssthresh == TCP_INFINITE_SSTHRESH) { + tcp_sk(sk)->snd_ssthresh = tcp_snd_cwnd(tp) / 2; + /* since this is the initial slow start, + * the min cwnd won't be 1, so the window + * can't be set to 0 by accident. + * Halfing the cwnd will undo the previous step + * of slow start. Which is fine since the pipe + * is already full. + */ + tcp_snd_cwnd_set(tp, max(tcp_snd_cwnd(tp) / 2, + TCP_INIT_CWND)); + } else { + tcp_sk(sk)->snd_ssthresh = + tcp_snd_cwnd(tp) - (tcp_snd_cwnd(tp) / 3); + tcp_snd_cwnd_set(tp, tcp_snd_cwnd(tp) - + (tcp_snd_cwnd(tp) / 3)); + } + ca->roccet_last_event_time_us = now; + return; + } - /* Handle initial slow start. Here occur most bufferbloat */ - if (tp->snd_ssthresh == TCP_INFINITE_SSTHRESH) { - tcp_sk(sk)->snd_ssthresh = tcp_snd_cwnd(tp) / 2; - /* since this is the initial slow start, - * the min cwnd won't be 1, so the window - * can't be set to 0 by accident. - */ - tcp_snd_cwnd_set(tp, max(tcp_snd_cwnd(tp) / 2, - TCP_INIT_CWND)); - } else { - tcp_sk(sk)->snd_ssthresh = - tcp_snd_cwnd(tp) - (tcp_snd_cwnd(tp) / 3); - tcp_snd_cwnd_set(tp, tcp_snd_cwnd(tp) - - (tcp_snd_cwnd(tp) / 3)); - } - ca->roccet_last_event_time_us = now; - return; - } + acked = tcp_slow_start(tp, acked); + if (!acked) + return; - if (tcp_in_slow_start(tp)) { - acked = tcp_slow_start(tp, acked); - if (!acked) - return; - } - - if (ca->next_srrtt_check == 0) - ca->next_srrtt_check = now + 5 * ca->curr_rtt; - - /* Check if it's time to evaluate the srRTT */ - if (after(now, ca->next_srrtt_check)) { - evaluate_srrtt = true; - - /* reset struct and set next end of period */ - ca->next_srrtt_check = now + 5 * ca->curr_rtt; - } - - /* Respects the jitter of the connection and add it on top of - * the upper bound for the srRTT. + }else if(ca->state == ORBITER){ + /* ORBITER: Increase the cwnd by using the CUBIC + * cwnd growth function, if no roccet congestion + * event is detechted. */ - roccet_xj = ((jitter * 100) / ca->curr_min_rtt) + - sr_rtt_upper_bound; - if (roccet_xj < sr_rtt_upper_bound) - roccet_xj = sr_rtt_upper_bound; + /* Calculate jitter */ + if ((s32)(ca->curr_rtt - ca->last_rtt) < 0) + jitter = ca->last_rtt - ca->curr_rtt; + else + jitter = ca->curr_rtt - ca->last_rtt; - /* The srRTT exceeds the upper bound if bufferbloat happens. - * Here, we want to reduce the cwnd and drain the buffer. - */ - if (ca->curr_srrtt > roccet_xj && evaluate_srrtt) { - roccet_congestion_event(sk, now); - return; - } + if (ca->next_srrtt_check == 0) + ca->next_srrtt_check = now + 5 * ca->curr_rtt; - /* Terminates this function if cwnd is not fully utilized. - * In mobile networks like 5G, this termination causes the cwnd to be - * frozen at an excessively high value. This is because slow start or - * HyStart massively exceed the available bandwidth and leave the cwnd - * at an excessively high value. The cwnd cannot therefore be fully - * utilized because it is limited by the connection capacity. - */ - if (!tcp_is_cwnd_limited(sk)) - return; + /* Check if it's time to evaluate the srRTT */ + if ((s32)(ca->next_srrtt_check - now) < 0) { + evaluate_srrtt = true; - bictcp_update(ca, tcp_snd_cwnd(tp), acked); - tcp_cong_avoid_ai(tp, max(1, ca->cnt), acked); + /* reset struct and set next end of period */ + ca->next_srrtt_check = now + 5 * ca->curr_rtt; + } + + /* Respects the jitter of the connection and add it on top of + * the upper bound for the srRTT. + */ + roccet_xj = div_u64((u64)jitter * 100, ca->curr_min_rtt) + + sr_rtt_upper_bound; + if (roccet_xj < sr_rtt_upper_bound) + roccet_xj = sr_rtt_upper_bound; + + /* The srRTT exceeds the upper bound if bufferbloat happens. + * Here, we want to reduce the cwnd and drain the buffer. + */ + if (ca->curr_srrtt > roccet_xj && evaluate_srrtt) { + roccet_congestion_event(sk, now); + return; + } + + /* Terminates this function if cwnd is not fully utilized. + * In mobile networks like 5G, this termination causes the cwnd to be + * frozen at an excessively high value. This is because slow start or + * HyStart massively exceed the available bandwidth and leave the cwnd + * at an excessively high value. The cwnd cannot therefore be fully + * utilized because it is limited by the connection capacity. + */ + if (!tcp_is_cwnd_limited(sk)) + return; + + bictcp_update(ca, tcp_snd_cwnd(tp), acked); + tcp_cong_avoid_ai(tp, max(1, ca->cnt), acked); + } } static u32 roccettcp_recalc_ssthresh(struct sock *sk) { const struct tcp_sock *tp = tcp_sk(sk); struct roccettcp *ca = inet_csk_ca(sk); + u32 cwnd; + + /* If a loss/ECN occurs in the refill pahse of min RTT probing + * we reduce the cwnd and abort the refill. + */ + if (ca->state == RTT_PROBE_REFILL) + ca->state = ORBITER; + + /* If ROCCET is in min RTT probing and a loss/ECN occurs, + * we use the cwnd before the probing interval to + * calculate the cwnd reduction and continue probing. + * After min RTT probing the cwnd is set to the reduced + * value. During min RTT probing it is very likely that + * congestion was caused by the cwnd value before min + * RTT probing. + */ + if (ca->state == RTT_PROBE){ + /* Handle ECN as cubic congestion event in min + * RTT probe. + */ + ca->ece_received = false; + + ca->epoch_start = 0; /* end of epoch */ + + /* Wmax and fast convergence */ + if (cwnd < ca->last_max_cwnd && fast_convergence) + ca->last_max_cwnd = + (cwnd * (BICTCP_BETA_SCALE + beta)) / + (2 * BICTCP_BETA_SCALE); + else + ca->last_max_cwnd = cwnd; + + cwnd = ca->cwnd_before_min_rtt_probe; + ca->cwnd_before_min_rtt_probe = max((cwnd * beta) / BICTCP_BETA_SCALE, 2U); + return cwnd; + } /* Handle ECN as ROCCET congestion event. */ if (ca->ece_received) { @@ -545,11 +640,14 @@ static u32 roccettcp_recalc_ssthresh(struct sock *sk) } /* On loss in slow start enter congestion avoidance - * without a cwnd reduction. + * without a cwnd reduction. Additional slow start + * exit conditions with a cwnd reduction are handled + * in roccettcp_cong_avoid. */ if (tcp_in_slow_start(tp)) return tcp_snd_cwnd(tp); + /*CUBIC congestion event*/ ca->epoch_start = 0; /* end of epoch */ /* Wmax and fast convergence */ @@ -566,13 +664,19 @@ static u32 roccettcp_recalc_ssthresh(struct sock *sk) static void roccettcp_state(struct sock *sk, u8 new_state) { struct roccettcp *ca = inet_csk_ca(sk); + struct tcp_sock *tp = tcp_sk(sk); - if (new_state == TCP_CA_Loss) + if (new_state == TCP_CA_Loss){ roccettcp_reset(ca); + } + else if(new_state == TCP_CA_Recovery){ + tcp_sk(sk)->snd_ssthresh = roccettcp_recalc_ssthresh(sk); + tcp_snd_cwnd_set(tp, tcp_sk(sk)->snd_ssthresh); + } } static void roccettcp_acked(struct sock *sk, - const struct ack_sample *sample) + const struct ack_sample *sample) { struct roccettcp *ca = inet_csk_ca(sk); @@ -590,7 +694,7 @@ static void roccettcp_acked(struct sock *sk, delay = 1; /* first time call or link delay decreases */ - if (ca->delay_min == 0 || after(ca->delay_min, delay)) + if (ca->delay_min == 0 || (s32)(delay - ca->delay_min) < 0) ca->delay_min = delay; /* Get valid sample for roccet */ @@ -611,17 +715,90 @@ static void roccet_in_ack_event(struct sock *sk, u32 flags) ca->ece_received = true; } +__bpf_kfunc static void roccet_control(struct sock *sk, u32 ack, int flag, const struct rate_sample *rs) { + struct tcp_sock *tp = tcp_sk(sk); + struct roccettcp *ca = inet_csk_ca(sk); + + u32 now = jiffies_to_usecs(tcp_jiffies32); + u64 rate; + + /* Update roccet parameters */ + update_ack_rate(sk, rs->acked_sacked, now); + update_min_rtt(sk); + update_srrtt(sk); + + /* Update roccet state */ + if(tcp_in_slow_start(tp)){ + ca->state = LAUNCH; + }else if((s32) now - ca->roccet_last_event_time_us <= 100 * USEC_PER_MSEC){ + ca->state = DRAIN; + } + else if(after(now, ca->next_min_rtt_probe) || ca->state == RTT_PROBE || ca->state == RTT_PROBE_REFILL){ + if(ca->state != RTT_PROBE_REFILL) + ca->state = RTT_PROBE; + roccet_min_rtt_probe(sk, now); + } + else{ + ca->state = ORBITER; + } + + /* If nothing was fully acked do not increase the cwnd */ + if (!rs->acked_sacked) + return; + + /* Increase the cwnd. + * Loss recovery is handled in roccettcp_state() + */ + roccettcp_cong_avoid(sk, ack, rs->acked_sacked); + + /* Adjust pacing rate. The code here is similar to the + * pacing rate adjustemnts in tcp_input.c tcp_cong_control(). + * In LAUNCH (slow start) we want a pacing of 200% and + * in ORBITER (congestion avoidance) we adjust the pacing + * to 100% and do not use the sysctl_tcp_pacing_ca_ratio. + */ + + /* set sk_pacing_rate to 200 % of current rate (mss * cwnd / srtt) */ + rate = (u64)tp->mss_cache * ((USEC_PER_SEC / 100) << 3); + + /* current rate is (cwnd * mss) / srtt + * In Slow Start [1], set sk_pacing_rate to 200 % the current rate. + * In Congestion Avoidance phase, set it to 120 % the current rate. + * + * [1] : Normal Slow Start condition is (tp->snd_cwnd < tp->snd_ssthresh) + * If snd_cwnd >= (tp->snd_ssthresh / 2), we are approaching + * end of slow start and should slow down. + */ + if (tcp_snd_cwnd(tp) < tp->snd_ssthresh / 2) + rate *= READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_pacing_ss_ratio); + else + /* Pacing rate of 100% (instead of ipv4.sysctl_tcp_pacing_ca_ratio) */ + rate *= 100; + + rate *= max(tcp_snd_cwnd(tp), tp->packets_out); + + if (likely(tp->srtt_us)) + do_div(rate, tp->srtt_us); + + /* WRITE_ONCE() is needed because sch_fq fetches sk_pacing_rate + * without any lock. We want to make sure compiler wont store + * intermediate values in this location. + */ + WRITE_ONCE(sk->sk_pacing_rate, + min_t(u64, rate, READ_ONCE(sk->sk_max_pacing_rate))); +} + static struct tcp_congestion_ops roccet_tcp __read_mostly = { - .init = roccettcp_init, - .ssthresh = roccettcp_recalc_ssthresh, - .cong_avoid = roccettcp_cong_avoid, - .set_state = roccettcp_state, - .undo_cwnd = tcp_reno_undo_cwnd, - .cwnd_event = roccettcp_cwnd_event, - .pkts_acked = roccettcp_acked, - .in_ack_event = roccet_in_ack_event, - .owner = THIS_MODULE, - .name = "roccet", + .init = roccettcp_init, + .ssthresh = roccettcp_recalc_ssthresh, + .set_state = roccettcp_state, + .undo_cwnd = tcp_reno_undo_cwnd, + .cwnd_event_tx_start = roccettcp_cwnd_event_tx_start, + .pkts_acked = roccettcp_acked, + .in_ack_event = roccet_in_ack_event, + .cong_control = roccet_control, + .owner = THIS_MODULE, + .name = "roccet", }; static int __init roccettcp_register(void) @@ -645,7 +822,6 @@ static int __init roccettcp_register(void) /* Precompute a bunch of the scaling factors that are used per-packet * based on SRTT of 100ms */ - beta_scale = 8 * (BICTCP_BETA_SCALE + beta) / 3 / (BICTCP_BETA_SCALE - beta); diff --git a/tcp_roccet.h b/tcp_roccet.h index b9037e9..1ee4d75 100644 --- a/tcp_roccet.h +++ b/tcp_roccet.h @@ -7,6 +7,16 @@ #include +/* State in which roccet currently opperates */ +enum roccet_state { + LAUNCH, + ORBITER, + RTT_PROBE, + RTT_PROBE_REFILL, + DRAIN +}; + +/* TCP ROCCET helper type, storing data related to ack counting */ struct ack_rate { u32 last_rate; /* Last ACK-rate */ u32 last_rate_time; /* Timestamp of the last ACK-rate */ @@ -14,8 +24,8 @@ struct ack_rate { u32 cnt; /* Used for counting acks */ }; -/* Based on the BICTCP struct with additions specific - * for the ROCCET-Algorithm +/* TCP ROCCET struct based on the original BICTCP struct with + * additions specific to the ROCCET-Algorithm. */ struct roccettcp { u32 cnt; /* increase cwnd by 1 after ACKs */ @@ -30,7 +40,7 @@ struct roccettcp { u32 epoch_start; /* beginning of an epoch */ u32 ack_cnt; /* number of acks */ u32 tcp_cwnd; /* estimated tcp cwnd */ - u32 curr_rtt; /* the minimum rtt of current round */ + u32 curr_rtt; /* last sample rtt of current round */ u32 roccet_last_event_time_us; /* The last time ROCCET was * triggered @@ -39,11 +49,15 @@ struct roccettcp { u32 curr_min_rtt; /* The current observed minRTT */ u32 next_min_rtt_probe; /* Next time to probe the minRTT */ u32 probe_min_rtt_until; /* End of minRTT probing period */ - u32 cwnd_before_min_rtt_probe; /* cwnd before min RTT probeing */ + u32 refill_until; /* End of pipe refill after minRTT probe */ + u32 cwnd_before_min_rtt_probe; /* cwnd before min RTT probeing */ u32 curr_srrtt; /* srRTT calculated based on the latest ACK */ u32 next_srrtt_check; /* Next check for srRTT */ struct ack_rate ack_rate; /* The last and the current ACK rate */ - u32 last_rtt; /* Used for jitter calculation */ + u32 last_rtt; /* sample rtt of previous round. + * Used for jitter calculation + */ + enum roccet_state state; /* State in which roccet currently opperates */ }; #endif /* __TCP_ROCCET_H */