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// SPDX-License-Identifier: GPL-2.0-only |
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/* |
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* TCP ROCCET: An RTT-Oriented CUBIC Congestion Control |
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* Extension for 5G and Beyond Networks |
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* |
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* TCP ROCCET is a new TCP congestion control |
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* algorithm suited for current cellular 5G NR beyond networks. |
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* It extends the kernel default congestion control CUBIC |
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* and improves its performance, and additionally solves an |
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* unwanted side effects of CUBIC’s implementation. |
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* ROCCET uses its own Slow Start, called LAUNCH, where loss |
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* is not considered as a congestion event. |
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* The congestion avoidance phase, called ORBITER, uses |
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* CUBIC's window growth function and adds, based on RTT |
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* and ACK rate, congestion events. |
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* |
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* NOTE: A paper for TCP ROCCET is currently under review. |
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* A draft of this paper can be found here: |
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* |
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* |
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* Further information about CUBIC: |
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* TCP CUBIC: Binary Increase Congestion control for TCP v2.3 |
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* Home page: |
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* http://netsrv.csc.ncsu.edu/twiki/bin/view/Main/BIC |
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* This is from the implementation of CUBIC TCP in |
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* Sangtae Ha, Injong Rhee and Lisong Xu, |
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* "CUBIC: A New TCP-Friendly High-Speed TCP Variant" |
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* in ACM SIGOPS Operating System Review, July 2008. |
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* Available from: |
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* http://netsrv.csc.ncsu.edu/export/cubic_a_new_tcp_2008.pdf |
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* |
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* CUBIC integrates a new slow start algorithm, called HyStart. |
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* The details of HyStart are presented in |
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* Sangtae Ha and Injong Rhee, |
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* "Taming the Elephants: New TCP Slow Start", NCSU TechReport 2008. |
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* Available from: |
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* http://netsrv.csc.ncsu.edu/export/hystart_techreport_2008.pdf |
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* |
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* All testing results are available from: |
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* http://netsrv.csc.ncsu.edu/wiki/index.php/TCP_Testing |
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* |
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* Unless CUBIC is enabled and congestion window is large |
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* this behaves the same as the original Reno. |
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*/ |
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#include "tcp_roccet.h" |
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#include "linux/printk.h" |
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#include <linux/btf.h> |
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#include <linux/btf_ids.h> |
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#include <linux/math64.h> |
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#include <linux/mm.h> |
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#include <linux/module.h> |
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#include <net/tcp.h> |
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/* Scale factor beta calculation (max_cwnd = snd_cwnd * beta) */ |
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#define BICTCP_BETA_SCALE 1024 |
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#define BICTCP_HZ 10 /* BIC HZ 2^10 = 1024 */ |
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/* Alpha value for the sRrTT multiplied by 100. |
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* Here 20 represents a value of 0.2 |
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*/ |
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#define ROCCET_ALPHA_TIMES_100 20 |
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/* The amount of seconds ROCCET stores a minRTT. |
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* Enable "calculate_min_rtt" first. |
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*/ |
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#define ROCCET_RTT_LOOKBACK_S 10 |
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/* Parameters that are specific to the ROCCET-Algorithm */ |
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static int sr_rtt_upper_bound __read_mostly = 100; |
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static int ack_rate_diff_ss __read_mostly = 10; |
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static int ack_rate_diff_ca __read_mostly = 200; |
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static int calculate_min_rtt __read_mostly = 0; |
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static int ignore_loss __read_mostly = 0; |
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static int roccet_minRTT_interpolation_factor __read_mostly = 70; |
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module_param(sr_rtt_upper_bound, int, 0644); |
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MODULE_PARM_DESC(sr_rtt_upper_bound, "ROCCET's upper bound for srRTT."); |
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module_param(ack_rate_diff_ss, int, 0644); |
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MODULE_PARM_DESC(ack_rate_diff_ss, |
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"ROCCET's threshold to exit slow start if ACK-rate defer by " |
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"given amount of segments."); |
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module_param(ack_rate_diff_ca, int, 0644); |
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MODULE_PARM_DESC(ack_rate_diff_ca, |
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"ROCCET's threshold for ack-rate and cum_cwnd, in percantage " |
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"of the current cwnd."); |
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module_param(calculate_min_rtt, int, 0644); |
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MODULE_PARM_DESC(calculate_min_rtt, |
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"Calculate min RTT if no lower RTT occurs after 10 sec."); |
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module_param(ignore_loss, int, 0644); |
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MODULE_PARM_DESC(ignore_loss, "Ignore loss as a congestion event."); |
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module_param(roccet_minRTT_interpolation_factor, int, 0644); |
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MODULE_PARM_DESC( |
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roccet_minRTT_interpolation_factor, |
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"ROCCET factor for interpolating the current RTT with the last minRTT " |
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"(minRTT = (factor * currRTT + (100-factor) * minRTT) / 100)"); |
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static int fast_convergence __read_mostly = 1; |
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static int beta __read_mostly = 717; /* = 717/1024 (BICTCP_BETA_SCALE) */ |
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static int initial_ssthresh __read_mostly; |
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static int bic_scale __read_mostly = 41; |
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static int tcp_friendliness __read_mostly = 1; |
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static u32 cube_rtt_scale __read_mostly; |
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static u32 beta_scale __read_mostly; |
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static u64 cube_factor __read_mostly; |
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/* Note parameters that are used for precomputing scale factors are read-only */ |
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module_param(fast_convergence, int, 0644); |
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MODULE_PARM_DESC(fast_convergence, "turn on/off fast convergence"); |
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module_param(beta, int, 0644); |
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MODULE_PARM_DESC(beta, "beta for multiplicative increase"); |
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module_param(initial_ssthresh, int, 0644); |
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MODULE_PARM_DESC(initial_ssthresh, "initial value of slow start threshold"); |
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module_param(bic_scale, int, 0444); |
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MODULE_PARM_DESC( |
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bic_scale, |
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"scale (scaled by 1024) value for bic function (bic_scale/1024)"); |
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module_param(tcp_friendliness, int, 0644); |
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MODULE_PARM_DESC(tcp_friendliness, "turn on/off tcp friendliness"); |
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static inline void roccettcp_reset(struct roccettcp *ca) |
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{ |
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memset(ca, 0, offsetof(struct roccettcp, curr_rtt)); |
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ca->bw_limit.sum_cwnd = 1; |
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ca->bw_limit.sum_acked = 1; |
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ca->bw_limit.next_check = 0; |
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ca->curr_min_rtt_timed.rtt = ~0U; |
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ca->curr_min_rtt_timed.time = ~0U; |
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ca->last_rtt = 0; |
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} |
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static inline void update_min_rtt(struct sock *sk) |
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{ |
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struct roccettcp *ca = inet_csk_ca(sk); |
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u32 now = jiffies_to_usecs(tcp_jiffies32); |
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if (now - ca->curr_min_rtt_timed.time > |
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ROCCET_RTT_LOOKBACK_S * USEC_PER_SEC && |
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calculate_min_rtt) { |
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u32 new_min_rtt = max(ca->curr_rtt, 1); |
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u32 old_min_rtt = ca->curr_min_rtt_timed.rtt; |
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u32 interpolated_min_rtt = |
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(new_min_rtt * roccet_minRTT_interpolation_factor + |
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old_min_rtt * |
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(100 - roccet_minRTT_interpolation_factor)) / |
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100; |
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ca->curr_min_rtt_timed.rtt = interpolated_min_rtt; |
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ca->curr_min_rtt_timed.time = now; |
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} |
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/* Check if new lower min RTT was found. If so, set it directly */ |
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if (ca->curr_rtt < ca->curr_min_rtt_timed.rtt) { |
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ca->curr_min_rtt_timed.rtt = max(ca->curr_rtt, 1); |
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ca->curr_min_rtt_timed.time = now; |
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} |
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} |
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/* Return difference between last and current ack rate. |
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*/ |
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static inline int get_ack_rate_diff(struct roccettcp *ca) |
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{ |
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return ca->ack_rate.last_rate - ca->ack_rate.curr_rate; |
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} |
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/* Update ack rate sampled by 100ms. |
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*/ |
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static inline void update_ack_rate(struct sock *sk) |
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{ |
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struct roccettcp *ca = inet_csk_ca(sk); |
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u32 now = jiffies_to_usecs(tcp_jiffies32); |
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u32 interval = USEC_PER_MSEC * 100; |
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if ((u32)(now - ca->ack_rate.last_rate_time) >= interval) { |
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ca->ack_rate.last_rate_time = now; |
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ca->ack_rate.last_rate = ca->ack_rate.curr_rate; |
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ca->ack_rate.curr_rate = ca->ack_rate.cnt; |
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ca->ack_rate.cnt = 0; |
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} else { |
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ca->ack_rate.cnt += 1; |
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} |
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} |
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/* Compute srRTT. |
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*/ |
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static inline void update_srrtt(struct sock *sk) |
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{ |
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struct roccettcp *ca = inet_csk_ca(sk); |
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if (ca->curr_min_rtt_timed.rtt == 0) |
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return; |
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/* Calculate the new rRTT (Scaled by 100). |
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* 100 * ((sRTT - sRTT_min) / sRTT_min) |
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*/ |
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u32 rRTT = (100 * (ca->curr_rtt - ca->curr_min_rtt_timed.rtt)) / |
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ca->curr_min_rtt_timed.rtt; |
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// (1 - alpha) * srRTT + alpha * rRTT |
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ca->curr_srRTT = ((100 - ROCCET_ALPHA_TIMES_100) * ca->curr_srRTT + |
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ROCCET_ALPHA_TIMES_100 * rRTT) / |
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100; |
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} |
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__bpf_kfunc static void roccettcp_init(struct sock *sk) |
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{ |
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struct roccettcp *ca = inet_csk_ca(sk); |
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roccettcp_reset(ca); |
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if (initial_ssthresh) |
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tcp_sk(sk)->snd_ssthresh = initial_ssthresh; |
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/* Initial roccet paramters */ |
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ca->roccet_last_event_time_us = 0; |
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ca->curr_min_rtt = ~0U; |
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ca->ack_rate.last_rate = 0; |
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ca->ack_rate.last_rate_time = 0; |
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ca->ack_rate.curr_rate = 0; |
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ca->ack_rate.cnt = 0; |
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} |
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__bpf_kfunc static void roccettcp_cwnd_event(struct sock *sk, |
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enum tcp_ca_event event) |
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{ |
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if (event == CA_EVENT_TX_START) { |
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struct roccettcp *ca = inet_csk_ca(sk); |
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u32 now = tcp_jiffies32; |
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s32 delta; |
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delta = now - tcp_sk(sk)->lsndtime; |
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/* We were application limited (idle) for a while. |
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* Shift epoch_start to keep cwnd growth to cubic curve. |
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*/ |
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if (ca->epoch_start && delta > 0) { |
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ca->epoch_start += delta; |
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if (after(ca->epoch_start, now)) |
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ca->epoch_start = now; |
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} |
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return; |
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} |
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} |
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/* calculate the cubic root of x using a table lookup followed by one |
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* Newton-Raphson iteration. |
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* Avg err ~= 0.195% |
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*/ |
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static u32 cubic_root(u64 a) |
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{ |
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u32 x, b, shift; |
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/* cbrt(x) MSB values for x MSB values in [0..63]. |
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* Precomputed then refined by hand - Willy Tarreau |
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* |
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* For x in [0..63], |
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* v = cbrt(x << 18) - 1 |
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* cbrt(x) = (v[x] + 10) >> 6 |
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*/ |
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static const u8 v[] = { |
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/* 0x00 */ 0, 54, 54, 54, 118, 118, 118, 118, |
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/* 0x08 */ 123, 129, 134, 138, 143, 147, 151, 156, |
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/* 0x10 */ 157, 161, 164, 168, 170, 173, 176, 179, |
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/* 0x18 */ 181, 185, 187, 190, 192, 194, 197, 199, |
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/* 0x20 */ 200, 202, 204, 206, 209, 211, 213, 215, |
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/* 0x28 */ 217, 219, 221, 222, 224, 225, 227, 229, |
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/* 0x30 */ 231, 232, 234, 236, 237, 239, 240, 242, |
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/* 0x38 */ 244, 245, 246, 248, 250, 251, 252, 254, |
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}; |
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b = fls64(a); |
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if (b < 7) { |
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/* a in [0..63] */ |
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return ((u32)v[(u32)a] + 35) >> 6; |
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} |
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b = ((b * 84) >> 8) - 1; |
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shift = (a >> (b * 3)); |
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x = ((u32)(((u32)v[shift] + 10) << b)) >> 6; |
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/* Newton-Raphson iteration |
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* 2 |
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* x = ( 2 * x + a / x ) / 3 |
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* k+1 k k |
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*/ |
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x = (2 * x + (u32)div64_u64(a, (u64)x * (u64)(x - 1))); |
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x = ((x * 341) >> 10); |
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return x; |
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} |
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/* Compute congestion window to use. |
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*/ |
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static inline void bictcp_update(struct roccettcp *ca, u32 cwnd, u32 acked) |
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{ |
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u32 delta, bic_target, max_cnt; |
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u64 offs, t; |
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ca->ack_cnt += acked; /* count the number of ACKed packets */ |
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if (ca->last_cwnd == cwnd && |
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(s32)(tcp_jiffies32 - ca->last_time) <= HZ / 32) |
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return; |
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/* The CUBIC function can update ca->cnt at most once per jiffy. |
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* On all cwnd reduction events, ca->epoch_start is set to 0, |
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* which will force a recalculation of ca->cnt. |
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*/ |
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if (ca->epoch_start && tcp_jiffies32 == ca->last_time) |
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goto tcp_friendliness; |
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ca->last_cwnd = cwnd; |
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ca->last_time = tcp_jiffies32; |
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if (ca->epoch_start == 0) { |
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ca->epoch_start = tcp_jiffies32; /* record beginning */ |
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ca->ack_cnt = acked; /* start counting */ |
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ca->tcp_cwnd = cwnd; /* syn with cubic */ |
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if (ca->last_max_cwnd <= cwnd) { |
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ca->bic_K = 0; |
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ca->bic_origin_point = cwnd; |
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} else { |
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/* Compute new K based on |
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* (wmax-cwnd) * (srtt>>3 / HZ) / c * 2^(3*bictcp_HZ) |
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*/ |
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ca->bic_K = cubic_root(cube_factor * |
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(ca->last_max_cwnd - cwnd)); |
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ca->bic_origin_point = ca->last_max_cwnd; |
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} |
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} |
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/* cubic function - calc */ |
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/* calculate c * time^3 / rtt, |
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* while considering overflow in calculation of time^3 |
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* (so time^3 is done by using 64 bit) |
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* and without the support of division of 64bit numbers |
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* (so all divisions are done by using 32 bit) |
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* also NOTE the unit of those veriables |
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* time = (t - K) / 2^bictcp_HZ |
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* c = bic_scale >> 10 |
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* rtt = (srtt >> 3) / HZ |
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* !!! The following code does not have overflow problems, |
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* if the cwnd < 1 million packets !!! |
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*/ |
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t = (s32)(tcp_jiffies32 - ca->epoch_start); |
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t += usecs_to_jiffies(ca->delay_min); |
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/* change the unit from HZ to bictcp_HZ */ |
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t <<= BICTCP_HZ; |
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do_div(t, HZ); |
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if (t < ca->bic_K) /* t - K */ |
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offs = ca->bic_K - t; |
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else |
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offs = t - ca->bic_K; |
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/* c/rtt * (t-K)^3 */ |
|
|
|
delta = (cube_rtt_scale * offs * offs * offs) >> (10 + 3 * BICTCP_HZ); |
|
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|
if (t < ca->bic_K) /* below origin*/ |
|
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|
bic_target = ca->bic_origin_point - delta; |
|
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|
else /* above origin*/ |
|
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|
bic_target = ca->bic_origin_point + delta; |
|
|
|
|
|
|
|
/* cubic function - calc bictcp_cnt*/ |
|
|
|
if (bic_target > cwnd) { |
|
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|
ca->cnt = cwnd / (bic_target - cwnd); |
|
|
|
} else { |
|
|
|
ca->cnt = 100 * cwnd; /* very small increment*/ |
|
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|
} |
|
|
|
|
|
|
|
/* The initial growth of cubic function may be too conservative |
|
|
|
* when the available bandwidth is still unknown. |
|
|
|
*/ |
|
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|
if (ca->last_max_cwnd == 0 && ca->cnt > 20) |
|
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|
ca->cnt = 20; /* increase cwnd 5% per RTT */ |
|
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|
|
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|
tcp_friendliness: |
|
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|
/* TCP Friendly */ |
|
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|
if (tcp_friendliness) { |
|
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|
u32 scale = beta_scale; |
|
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|
|
|
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|
delta = (cwnd * scale) >> 3; |
|
|
|
while (ca->ack_cnt > delta) { /* update tcp cwnd */ |
|
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|
ca->ack_cnt -= delta; |
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|
ca->tcp_cwnd++; |
|
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|
} |
|
|
|
|
|
|
|
if (ca->tcp_cwnd > cwnd) { /* if bic is slower than tcp */ |
|
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|
delta = ca->tcp_cwnd - cwnd; |
|
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|
max_cnt = cwnd / delta; |
|
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|
if (ca->cnt > max_cnt) |
|
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|
ca->cnt = max_cnt; |
|
|
|
} |
|
|
|
} |
|
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|
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|
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|
/* The maximum rate of cwnd increase CUBIC allows is 1 packet per |
|
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|
* 2 packets ACKed, meaning cwnd grows at 1.5x per RTT. |
|
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|
*/ |
|
|
|
ca->cnt = max(ca->cnt, 2U); |
|
|
|
} |
|
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|
|
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|
__bpf_kfunc static void roccettcp_cong_avoid(struct sock *sk, u32 ack, |
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|
u32 acked) |
|
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|
{ |
|
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|
struct tcp_sock *tp = tcp_sk(sk); |
|
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|
struct roccettcp *ca = inet_csk_ca(sk); |
|
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|
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|
|
u32 now = jiffies_to_usecs(tcp_jiffies32); |
|
|
|
u32 bw_limit_detect = 0; |
|
|
|
u32 roccet_xj; |
|
|
|
u32 jitter; |
|
|
|
if (ca->last_rtt > ca->curr_rtt) { |
|
|
|
jitter = ca->last_rtt - ca->curr_rtt; |
|
|
|
} else { |
|
|
|
jitter = ca->curr_rtt - ca->last_rtt; |
|
|
|
} |
|
|
|
|
|
|
|
/* Update roccet paramters */ |
|
|
|
update_ack_rate(sk); |
|
|
|
update_min_rtt(sk); |
|
|
|
update_srrtt(sk); |
|
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|
|
|
|
/* ROCCET drain. |
|
|
|
* Do not increase the cwnd for 100ms after a roccet congestion event |
|
|
|
*/ |
|
|
|
if (now - ca->roccet_last_event_time_us <= 100 * USEC_PER_MSEC) |
|
|
|
return; |
|
|
|
|
|
|
|
/* Lift off: Detect an exit point for tcp slow start |
|
|
|
* in networks with large buffers of multiple BDP |
|
|
|
* Like in cellular networks (5G, ...). |
|
|
|
*/ |
|
|
|
if (tcp_in_slow_start(tp) && ca->curr_srRTT > sr_rtt_upper_bound && |
|
|
|
get_ack_rate_diff(ca) >= ack_rate_diff_ss) { |
|
|
|
ca->epoch_start = 0; |
|
|
|
|
|
|
|
/* Handle inital slow start. Here we observe the most problems */ |
|
|
|
if (tp->snd_ssthresh == TCP_INFINITE_SSTHRESH) { |
|
|
|
tcp_sk(sk)->snd_ssthresh = tcp_snd_cwnd(tp) / 2; |
|
|
|
tcp_snd_cwnd_set(tp, tcp_snd_cwnd(tp) / 2); |
|
|
|
} 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; |
|
|
|
} |
|
|
|
|
|
|
|
if (tcp_in_slow_start(tp)) { |
|
|
|
acked = tcp_slow_start(tp, acked); |
|
|
|
if (!acked) |
|
|
|
return; |
|
|
|
} |
|
|
|
|
|
|
|
if (ca->bw_limit.next_check == 0) |
|
|
|
ca->bw_limit.next_check = now + 5 * ca->curr_rtt; |
|
|
|
|
|
|
|
ca->bw_limit.sum_cwnd += tcp_snd_cwnd(tp); |
|
|
|
ca->bw_limit.sum_acked += acked; |
|
|
|
|
|
|
|
if (ca->bw_limit.next_check < now) { |
|
|
|
/* We send more data as we got acked in the last 5 RTTs */ |
|
|
|
if ((ca->bw_limit.sum_cwnd * 100) / ca->bw_limit.sum_acked >= |
|
|
|
ack_rate_diff_ca) |
|
|
|
bw_limit_detect = 1; |
|
|
|
|
|
|
|
/* reset struct and set next end of period */ |
|
|
|
ca->bw_limit.sum_cwnd = 1; |
|
|
|
|
|
|
|
/* set to 1 to avoid division by zero */ |
|
|
|
ca->bw_limit.sum_acked = 1; |
|
|
|
ca->bw_limit.next_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 = ((jitter * 100) / ca->curr_min_rtt_timed.rtt) + |
|
|
|
sr_rtt_upper_bound; |
|
|
|
if (roccet_xj < sr_rtt_upper_bound) |
|
|
|
roccet_xj = sr_rtt_upper_bound; |
|
|
|
|
|
|
|
if (ca->curr_srRTT > roccet_xj && bw_limit_detect) { |
|
|
|
ca->epoch_start = 0; |
|
|
|
ca->roccet_last_event_time_us = now; |
|
|
|
ca->cnt = 100 * tcp_snd_cwnd(tp); |
|
|
|
|
|
|
|
/* Set Wmax if cwnd is larger than the old Wmax */ |
|
|
|
if (tcp_snd_cwnd(tp) > ca->last_max_cwnd) |
|
|
|
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))); |
|
|
|
tp->snd_ssthresh = tcp_snd_cwnd(tp); |
|
|
|
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); |
|
|
|
} |
|
|
|
|
|
|
|
__bpf_kfunc static u32 roccettcp_recalc_ssthresh(struct sock *sk) |
|
|
|
{ |
|
|
|
const struct tcp_sock *tp = tcp_sk(sk); |
|
|
|
struct roccettcp *ca = inet_csk_ca(sk); |
|
|
|
|
|
|
|
if (ignore_loss) |
|
|
|
return tcp_snd_cwnd(tp); |
|
|
|
|
|
|
|
/* Don't exit slow start if loss occurs. */ |
|
|
|
if (tcp_in_slow_start(tp)) |
|
|
|
return tcp_snd_cwnd(tp); |
|
|
|
|
|
|
|
ca->epoch_start = 0; /* end of epoch */ |
|
|
|
|
|
|
|
/* Wmax and fast convergence */ |
|
|
|
if (tcp_snd_cwnd(tp) < ca->last_max_cwnd && fast_convergence) |
|
|
|
ca->last_max_cwnd = |
|
|
|
(tcp_snd_cwnd(tp) * (BICTCP_BETA_SCALE + beta)) / |
|
|
|
(2 * BICTCP_BETA_SCALE); |
|
|
|
else |
|
|
|
ca->last_max_cwnd = tcp_snd_cwnd(tp); |
|
|
|
|
|
|
|
return max((tcp_snd_cwnd(tp) * beta) / BICTCP_BETA_SCALE, 2U); |
|
|
|
} |
|
|
|
|
|
|
|
__bpf_kfunc static void roccettcp_state(struct sock *sk, u8 new_state) |
|
|
|
{ |
|
|
|
struct roccettcp *ca = inet_csk_ca(sk); |
|
|
|
if (new_state == TCP_CA_Loss) |
|
|
|
roccettcp_reset(ca); |
|
|
|
} |
|
|
|
|
|
|
|
__bpf_kfunc static void roccettcp_acked(struct sock *sk, |
|
|
|
const struct ack_sample *sample) |
|
|
|
{ |
|
|
|
struct roccettcp *ca = inet_csk_ca(sk); |
|
|
|
|
|
|
|
/* Some calls are for duplicates without timestamps */ |
|
|
|
if (sample->rtt_us < 0) |
|
|
|
return; |
|
|
|
|
|
|
|
/* Discard delay samples right after fast recovery */ |
|
|
|
if (ca->epoch_start && (s32)(tcp_jiffies32 - ca->epoch_start) < HZ) |
|
|
|
return; |
|
|
|
|
|
|
|
u32 delay = sample->rtt_us; |
|
|
|
if (delay == 0) |
|
|
|
delay = 1; |
|
|
|
|
|
|
|
/* first time call or link delay decreases */ |
|
|
|
if (ca->delay_min == 0 || ca->delay_min > delay) |
|
|
|
ca->delay_min = delay; |
|
|
|
|
|
|
|
/* Get valid sample for roccet */ |
|
|
|
if (sample->rtt_us > 0) { |
|
|
|
ca->last_rtt = ca->curr_rtt; |
|
|
|
ca->curr_rtt = sample->rtt_us; |
|
|
|
} |
|
|
|
} |
|
|
|
|
|
|
|
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, |
|
|
|
.owner = THIS_MODULE, |
|
|
|
.name = "roccet", |
|
|
|
}; |
|
|
|
|
|
|
|
BTF_KFUNCS_START(tcp_roccet_check_kfunc_ids) |
|
|
|
BTF_ID_FLAGS(func, roccettcp_init) |
|
|
|
BTF_ID_FLAGS(func, roccettcp_recalc_ssthresh) |
|
|
|
BTF_ID_FLAGS(func, roccettcp_cong_avoid) |
|
|
|
BTF_ID_FLAGS(func, roccettcp_state) |
|
|
|
BTF_ID_FLAGS(func, roccettcp_cwnd_event) |
|
|
|
BTF_ID_FLAGS(func, roccettcp_acked) |
|
|
|
BTF_KFUNCS_END(tcp_roccet_check_kfunc_ids) |
|
|
|
|
|
|
|
static const struct btf_kfunc_id_set tcp_roccet_kfunc_set = { |
|
|
|
.owner = THIS_MODULE, |
|
|
|
.set = &tcp_roccet_check_kfunc_ids, |
|
|
|
}; |
|
|
|
|
|
|
|
static int __init roccettcp_register(void) |
|
|
|
{ |
|
|
|
int ret; |
|
|
|
|
|
|
|
BUILD_BUG_ON(sizeof(struct roccettcp) > ICSK_CA_PRIV_SIZE); |
|
|
|
|
|
|
|
/* 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); |
|
|
|
|
|
|
|
cube_rtt_scale = (bic_scale * 10); /* 1024*c/rtt */ |
|
|
|
|
|
|
|
/* calculate the "K" for (wmax-cwnd) = c/rtt * K^3 |
|
|
|
* so K = cubic_root( (wmax-cwnd)*rtt/c ) |
|
|
|
* the unit of K is bictcp_HZ=2^10, not HZ |
|
|
|
* |
|
|
|
* c = bic_scale >> 10 |
|
|
|
* rtt = 100ms |
|
|
|
* |
|
|
|
* the following code has been designed and tested for |
|
|
|
* cwnd < 1 million packets |
|
|
|
* RTT < 100 seconds |
|
|
|
* HZ < 1,000,00 (corresponding to 10 nano-second) |
|
|
|
*/ |
|
|
|
|
|
|
|
/* 1/c * 2^2*bictcp_HZ * srtt */ |
|
|
|
cube_factor = 1ull << (10 + 3 * BICTCP_HZ); /* 2^40 */ |
|
|
|
|
|
|
|
/* divide by bic_scale and by constant Srtt (100ms) */ |
|
|
|
do_div(cube_factor, bic_scale * 10); |
|
|
|
|
|
|
|
ret = register_btf_kfunc_id_set(BPF_PROG_TYPE_STRUCT_OPS, |
|
|
|
&tcp_roccet_kfunc_set); |
|
|
|
if (ret < 0) |
|
|
|
return ret; |
|
|
|
return tcp_register_congestion_control(&roccet_tcp); |
|
|
|
} |
|
|
|
|
|
|
|
static void __exit roccettcp_unregister(void) |
|
|
|
{ |
|
|
|
tcp_unregister_congestion_control(&roccet_tcp); |
|
|
|
} |
|
|
|
|
|
|
|
module_init(roccettcp_register); |
|
|
|
module_exit(roccettcp_unregister); |
|
|
|
|
|
|
|
MODULE_AUTHOR("Lukas Prause, Tim Füchsel"); |
|
|
|
MODULE_LICENSE("GPL"); |
|
|
|
MODULE_DESCRIPTION("ROCCET TCP"); |
|
|
|
MODULE_VERSION("1.0"); |
Lukas Prause
1 month ago