Initial commit for TCP ROCCET source code.
This commit is contained in:
Lukas Prause
656
tcp_roccet.c
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656
tcp_roccet.c
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@@ -0,0 +1,656 @@
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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 */
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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;
|
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|
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/* cubic function - calc bictcp_cnt*/
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if (bic_target > cwnd) {
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ca->cnt = cwnd / (bic_target - cwnd);
|
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} else {
|
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ca->cnt = 100 * cwnd; /* very small increment*/
|
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}
|
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|
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/* The initial growth of cubic function may be too conservative
|
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* when the available bandwidth is still unknown.
|
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*/
|
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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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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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delta = (cwnd * scale) >> 3;
|
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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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}
|
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|
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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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|
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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.
|
||||
*/
|
||||
ca->cnt = max(ca->cnt, 2U);
|
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}
|
||||
|
||||
__bpf_kfunc static void roccettcp_cong_avoid(struct sock *sk, u32 ack,
|
||||
u32 acked)
|
||||
{
|
||||
struct tcp_sock *tp = tcp_sk(sk);
|
||||
struct roccettcp *ca = inet_csk_ca(sk);
|
||||
|
||||
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);
|
||||
|
||||
/* 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");
|
||||
Reference in New Issue
Block a user