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Diffstat (limited to 'sys/netinet/cc/cc_cdg.c')
| -rw-r--r-- | sys/netinet/cc/cc_cdg.c | 695 |
1 files changed, 695 insertions, 0 deletions
diff --git a/sys/netinet/cc/cc_cdg.c b/sys/netinet/cc/cc_cdg.c new file mode 100644 index 0000000..69335db --- /dev/null +++ b/sys/netinet/cc/cc_cdg.c @@ -0,0 +1,695 @@ +/*- + * Copyright (c) 2009-2013 + * Swinburne University of Technology, Melbourne, Australia + * All rights reserved. + * + * This software was developed at the Centre for Advanced Internet + * Architectures, Swinburne University of Technology, by David Hayes, made + * possible in part by a gift from The Cisco University Research Program Fund, + * a corporate advised fund of Silicon Valley Community Foundation. Development + * and testing were further assisted by a grant from the FreeBSD Foundation. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * 1. Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution. + * + * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND + * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE + * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE + * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE + * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL + * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS + * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) + * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT + * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY + * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF + * SUCH DAMAGE. + */ + +/* + * CAIA Delay-Gradient (CDG) congestion control algorithm + * + * An implemention of the delay-gradient congestion control algorithm proposed + * in the following paper: + * + * D. A. Hayes and G. Armitage, "Revisiting TCP Congestion Control using Delay + * Gradients", in IFIP Networking, Valencia, Spain, 9-13 May 2011. + * + * Developed as part of the NewTCP research project at Swinburne University of + * Technology's Centre for Advanced Internet Architectures, Melbourne, + * Australia. More details are available at: + * http://caia.swin.edu.au/urp/newtcp/ + */ + +#include <sys/cdefs.h> +__FBSDID("$FreeBSD$"); + +#include <sys/param.h> +#include <sys/hhook.h> +#include <sys/kernel.h> +#include <sys/khelp.h> +#include <sys/limits.h> +#include <sys/lock.h> +#include <sys/malloc.h> +#include <sys/module.h> +#include <sys/queue.h> +#include <sys/socket.h> +#include <sys/socketvar.h> +#include <sys/sysctl.h> +#include <sys/systm.h> + +#include <net/if.h> +#include <net/vnet.h> + +#include <netinet/cc.h> +#include <netinet/tcp_seq.h> +#include <netinet/tcp_timer.h> +#include <netinet/tcp_var.h> + +#include <netinet/cc/cc_module.h> + +#include <netinet/khelp/h_ertt.h> + +#include <vm/uma.h> + +#define CDG_VERSION "0.1" + +#define CAST_PTR_INT(X) (*((int*)(X))) + +#ifndef VIMAGE +#define vnet_sysctl_handle_uint(oidp, arg1, arg2, req) \ + sysctl_handle_int(oidp, arg1, arg2, req) +#endif + +/* Private delay-gradient induced congestion control signal. */ +#define CC_CDG_DELAY 0x01000000 + +/* NewReno window deflation factor on loss (as a percentage). */ +#define RENO_BETA 50 + +/* Queue states. */ +#define CDG_Q_EMPTY 1 +#define CDG_Q_RISING 2 +#define CDG_Q_FALLING 3 +#define CDG_Q_FULL 4 +#define CDG_Q_UNKNOWN 9999 + +/* Number of bit shifts used in probexp lookup table. */ +#define EXP_PREC 15 + +/* Largest gradient represented in probexp lookup table. */ +#define MAXGRAD 5 + +/* + * Delay Precision Enhance - number of bit shifts used for qtrend related + * integer arithmetic precision. + */ +#define D_P_E 7 + +struct qdiff_sample { + long qdiff; + STAILQ_ENTRY(qdiff_sample) qdiff_lnk; +}; + +struct cdg { + long max_qtrend; + long min_qtrend; + STAILQ_HEAD(minrtts_head, qdiff_sample) qdiffmin_q; + STAILQ_HEAD(maxrtts_head, qdiff_sample) qdiffmax_q; + long window_incr; + /* rttcount for window increase when in congestion avoidance */ + long rtt_count; + /* maximum measured rtt within an rtt period */ + int maxrtt_in_rtt; + /* maximum measured rtt within prev rtt period */ + int maxrtt_in_prevrtt; + /* minimum measured rtt within an rtt period */ + int minrtt_in_rtt; + /* minimum measured rtt within prev rtt period */ + int minrtt_in_prevrtt; + /* consecutive congestion episode counter */ + uint32_t consec_cong_cnt; + /* when tracking a new reno type loss window */ + uint32_t shadow_w; + /* maximum number of samples in the moving average queue */ + int sample_q_size; + /* number of samples in the moving average queue */ + int num_samples; + /* estimate of the queue state of the path */ + int queue_state; +}; + +/* + * Lookup table for: + * (1 - exp(-x)) << EXP_PREC, where x = [0,MAXGRAD] in 2^-7 increments + * + * Note: probexp[0] is set to 10 (not 0) as a safety for very low increase + * gradients. + */ +static const int probexp[641] = { + 10,255,508,759,1008,1255,1501,1744,1985,2225,2463,2698,2932,3165,3395,3624, + 3850,4075,4299,4520,4740,4958,5175,5389,5602,5814,6024,6232,6438,6643,6846, + 7048,7248,7447,7644,7839,8033,8226,8417,8606,8794,8981,9166,9350,9532,9713, + 9892,10070,10247,10422,10596,10769,10940,11110,11278,11445,11611,11776,11939, + 12101,12262,12422,12580,12737,12893,13048,13201,13354,13505,13655,13803,13951, + 14097,14243,14387,14530,14672,14813,14952,15091,15229,15365,15500,15635,15768, + 15900,16032,16162,16291,16419,16547,16673,16798,16922,17046,17168,17289,17410, + 17529,17648,17766,17882,17998,18113,18227,18340,18453,18564,18675,18784,18893, + 19001,19108,19215,19320,19425,19529,19632,19734,19835,19936,20036,20135,20233, + 20331,20427,20523,20619,20713,20807,20900,20993,21084,21175,21265,21355,21444, + 21532,21619,21706,21792,21878,21962,22046,22130,22213,22295,22376,22457,22537, + 22617,22696,22774,22852,22929,23006,23082,23157,23232,23306,23380,23453,23525, + 23597,23669,23739,23810,23879,23949,24017,24085,24153,24220,24286,24352,24418, + 24483,24547,24611,24675,24738,24800,24862,24924,24985,25045,25106,25165,25224, + 25283,25341,25399,25456,25513,25570,25626,25681,25737,25791,25846,25899,25953, + 26006,26059,26111,26163,26214,26265,26316,26366,26416,26465,26514,26563,26611, + 26659,26707,26754,26801,26847,26893,26939,26984,27029,27074,27118,27162,27206, + 27249,27292,27335,27377,27419,27460,27502,27543,27583,27624,27664,27703,27743, + 27782,27821,27859,27897,27935,27973,28010,28047,28084,28121,28157,28193,28228, + 28263,28299,28333,28368,28402,28436,28470,28503,28536,28569,28602,28634,28667, + 28699,28730,28762,28793,28824,28854,28885,28915,28945,28975,29004,29034,29063, + 29092,29120,29149,29177,29205,29232,29260,29287,29314,29341,29368,29394,29421, + 29447,29472,29498,29524,29549,29574,29599,29623,29648,29672,29696,29720,29744, + 29767,29791,29814,29837,29860,29882,29905,29927,29949,29971,29993,30014,30036, + 30057,30078,30099,30120,30141,30161,30181,30201,30221,30241,30261,30280,30300, + 30319,30338,30357,30376,30394,30413,30431,30449,30467,30485,30503,30521,30538, + 30555,30573,30590,30607,30624,30640,30657,30673,30690,30706,30722,30738,30753, + 30769,30785,30800,30815,30831,30846,30861,30876,30890,30905,30919,30934,30948, + 30962,30976,30990,31004,31018,31031,31045,31058,31072,31085,31098,31111,31124, + 31137,31149,31162,31174,31187,31199,31211,31223,31235,31247,31259,31271,31283, + 31294,31306,31317,31328,31339,31351,31362,31373,31383,31394,31405,31416,31426, + 31436,31447,31457,31467,31477,31487,31497,31507,31517,31527,31537,31546,31556, + 31565,31574,31584,31593,31602,31611,31620,31629,31638,31647,31655,31664,31673, + 31681,31690,31698,31706,31715,31723,31731,31739,31747,31755,31763,31771,31778, + 31786,31794,31801,31809,31816,31824,31831,31838,31846,31853,31860,31867,31874, + 31881,31888,31895,31902,31908,31915,31922,31928,31935,31941,31948,31954,31960, + 31967,31973,31979,31985,31991,31997,32003,32009,32015,32021,32027,32033,32038, + 32044,32050,32055,32061,32066,32072,32077,32083,32088,32093,32098,32104,32109, + 32114,32119,32124,32129,32134,32139,32144,32149,32154,32158,32163,32168,32173, + 32177,32182,32186,32191,32195,32200,32204,32209,32213,32217,32222,32226,32230, + 32234,32238,32242,32247,32251,32255,32259,32263,32267,32270,32274,32278,32282, + 32286,32290,32293,32297,32301,32304,32308,32311,32315,32318,32322,32325,32329, + 32332,32336,32339,32342,32346,32349,32352,32356,32359,32362,32365,32368,32371, + 32374,32377,32381,32384,32387,32389,32392,32395,32398,32401,32404,32407,32410, + 32412,32415,32418,32421,32423,32426,32429,32431,32434,32437,32439,32442,32444, + 32447,32449,32452,32454,32457,32459,32461,32464,32466,32469,32471,32473,32476, + 32478,32480,32482,32485,32487,32489,32491,32493,32495,32497,32500,32502,32504, + 32506,32508,32510,32512,32514,32516,32518,32520,32522,32524,32526,32527,32529, + 32531,32533,32535,32537,32538,32540,32542,32544,32545,32547}; + +static uma_zone_t qdiffsample_zone; + +static MALLOC_DEFINE(M_CDG, "cdg data", + "Per connection data required for the CDG congestion control algorithm"); + +static int ertt_id; + +static VNET_DEFINE(uint32_t, cdg_alpha_inc); +static VNET_DEFINE(uint32_t, cdg_beta_delay); +static VNET_DEFINE(uint32_t, cdg_beta_loss); +static VNET_DEFINE(uint32_t, cdg_smoothing_factor); +static VNET_DEFINE(uint32_t, cdg_exp_backoff_scale); +static VNET_DEFINE(uint32_t, cdg_consec_cong); +static VNET_DEFINE(uint32_t, cdg_hold_backoff); +#define V_cdg_alpha_inc VNET(cdg_alpha_inc) +#define V_cdg_beta_delay VNET(cdg_beta_delay) +#define V_cdg_beta_loss VNET(cdg_beta_loss) +#define V_cdg_smoothing_factor VNET(cdg_smoothing_factor) +#define V_cdg_exp_backoff_scale VNET(cdg_exp_backoff_scale) +#define V_cdg_consec_cong VNET(cdg_consec_cong) +#define V_cdg_hold_backoff VNET(cdg_hold_backoff) + +/* Function prototypes. */ +static int cdg_mod_init(void); +static void cdg_conn_init(struct cc_var *ccv); +static int cdg_cb_init(struct cc_var *ccv); +static void cdg_cb_destroy(struct cc_var *ccv); +static void cdg_cong_signal(struct cc_var *ccv, uint32_t signal_type); +static void cdg_ack_received(struct cc_var *ccv, uint16_t ack_type); + +struct cc_algo cdg_cc_algo = { + .name = "cdg", + .mod_init = cdg_mod_init, + .ack_received = cdg_ack_received, + .cb_destroy = cdg_cb_destroy, + .cb_init = cdg_cb_init, + .conn_init = cdg_conn_init, + .cong_signal = cdg_cong_signal +}; + +/* Vnet created and being initialised. */ +static void +cdg_init_vnet(const void *unused __unused) +{ + + V_cdg_alpha_inc = 0; + V_cdg_beta_delay = 70; + V_cdg_beta_loss = 50; + V_cdg_smoothing_factor = 8; + V_cdg_exp_backoff_scale = 3; + V_cdg_consec_cong = 5; + V_cdg_hold_backoff = 5; +} + +static int +cdg_mod_init(void) +{ + VNET_ITERATOR_DECL(v); + + ertt_id = khelp_get_id("ertt"); + if (ertt_id <= 0) + return (EINVAL); + + qdiffsample_zone = uma_zcreate("cdg_qdiffsample", + sizeof(struct qdiff_sample), NULL, NULL, NULL, NULL, 0, 0); + + VNET_LIST_RLOCK(); + VNET_FOREACH(v) { + CURVNET_SET(v); + cdg_init_vnet(NULL); + CURVNET_RESTORE(); + } + VNET_LIST_RUNLOCK(); + + cdg_cc_algo.post_recovery = newreno_cc_algo.post_recovery; + cdg_cc_algo.after_idle = newreno_cc_algo.after_idle; + + return (0); +} + +static int +cdg_cb_init(struct cc_var *ccv) +{ + struct cdg *cdg_data; + + cdg_data = malloc(sizeof(struct cdg), M_CDG, M_NOWAIT); + if (cdg_data == NULL) + return (ENOMEM); + + cdg_data->shadow_w = 0; + cdg_data->max_qtrend = 0; + cdg_data->min_qtrend = 0; + cdg_data->queue_state = CDG_Q_UNKNOWN; + cdg_data->maxrtt_in_rtt = 0; + cdg_data->maxrtt_in_prevrtt = 0; + cdg_data->minrtt_in_rtt = INT_MAX; + cdg_data->minrtt_in_prevrtt = 0; + cdg_data->window_incr = 0; + cdg_data->rtt_count = 0; + cdg_data->consec_cong_cnt = 0; + cdg_data->sample_q_size = V_cdg_smoothing_factor; + cdg_data->num_samples = 0; + STAILQ_INIT(&cdg_data->qdiffmin_q); + STAILQ_INIT(&cdg_data->qdiffmax_q); + + ccv->cc_data = cdg_data; + + return (0); +} + +static void +cdg_conn_init(struct cc_var *ccv) +{ + struct cdg *cdg_data = ccv->cc_data; + + /* + * Initialise the shadow_cwnd in case we are competing with loss based + * flows from the start + */ + cdg_data->shadow_w = CCV(ccv, snd_cwnd); +} + +static void +cdg_cb_destroy(struct cc_var *ccv) +{ + struct cdg *cdg_data; + struct qdiff_sample *qds, *qds_n; + + cdg_data = ccv->cc_data; + + qds = STAILQ_FIRST(&cdg_data->qdiffmin_q); + while (qds != NULL) { + qds_n = STAILQ_NEXT(qds, qdiff_lnk); + uma_zfree(qdiffsample_zone,qds); + qds = qds_n; + } + + qds = STAILQ_FIRST(&cdg_data->qdiffmax_q); + while (qds != NULL) { + qds_n = STAILQ_NEXT(qds, qdiff_lnk); + uma_zfree(qdiffsample_zone,qds); + qds = qds_n; + } + + free(ccv->cc_data, M_CDG); +} + +static int +cdg_beta_handler(SYSCTL_HANDLER_ARGS) +{ + + if (req->newptr != NULL && + (CAST_PTR_INT(req->newptr) == 0 || CAST_PTR_INT(req->newptr) > 100)) + return (EINVAL); + + return (vnet_sysctl_handle_uint(oidp, arg1, arg2, req)); +} + +static int +cdg_exp_backoff_scale_handler(SYSCTL_HANDLER_ARGS) +{ + + if (req->newptr != NULL && CAST_PTR_INT(req->newptr) < 1) + return (EINVAL); + + return (vnet_sysctl_handle_uint(oidp, arg1, arg2, req)); +} + +static inline unsigned long +cdg_window_decrease(struct cc_var *ccv, unsigned long owin, unsigned int beta) +{ + + return ((ulmin(CCV(ccv, snd_wnd), owin) * beta) / 100); +} + +/* + * Window increase function + * This window increase function is independent of the initial window size + * to ensure small window flows are not discriminated against (i.e. fairness). + * It increases at 1pkt/rtt like Reno for alpha_inc rtts, and then 2pkts/rtt for + * the next alpha_inc rtts, etc. + */ +static void +cdg_window_increase(struct cc_var *ccv, int new_measurement) +{ + struct cdg *cdg_data; + int incr, s_w_incr; + + cdg_data = ccv->cc_data; + incr = s_w_incr = 0; + + if (CCV(ccv, snd_cwnd) <= CCV(ccv, snd_ssthresh)) { + /* Slow start. */ + incr = CCV(ccv, t_maxseg); + s_w_incr = incr; + cdg_data->window_incr = cdg_data->rtt_count = 0; + } else { + /* Congestion avoidance. */ + if (new_measurement) { + s_w_incr = CCV(ccv, t_maxseg); + if (V_cdg_alpha_inc == 0) { + incr = CCV(ccv, t_maxseg); + } else { + if (++cdg_data->rtt_count >= V_cdg_alpha_inc) { + cdg_data->window_incr++; + cdg_data->rtt_count = 0; + } + incr = CCV(ccv, t_maxseg) * + cdg_data->window_incr; + } + } + } + + if (cdg_data->shadow_w > 0) + cdg_data->shadow_w = ulmin(cdg_data->shadow_w + s_w_incr, + TCP_MAXWIN << CCV(ccv, snd_scale)); + + CCV(ccv, snd_cwnd) = ulmin(CCV(ccv, snd_cwnd) + incr, + TCP_MAXWIN << CCV(ccv, snd_scale)); +} + +static void +cdg_cong_signal(struct cc_var *ccv, uint32_t signal_type) +{ + struct cdg *cdg_data = ccv->cc_data; + + switch(signal_type) { + case CC_CDG_DELAY: + CCV(ccv, snd_ssthresh) = cdg_window_decrease(ccv, + CCV(ccv, snd_cwnd), V_cdg_beta_delay); + CCV(ccv, snd_cwnd) = CCV(ccv, snd_ssthresh); + CCV(ccv, snd_recover) = CCV(ccv, snd_max); + cdg_data->window_incr = cdg_data->rtt_count = 0; + ENTER_CONGRECOVERY(CCV(ccv, t_flags)); + break; + case CC_NDUPACK: + /* + * If already responding to congestion OR we have guessed no + * queue in the path is full. + */ + if (IN_CONGRECOVERY(CCV(ccv, t_flags)) || + cdg_data->queue_state < CDG_Q_FULL) { + CCV(ccv, snd_ssthresh) = CCV(ccv, snd_cwnd); + CCV(ccv, snd_recover) = CCV(ccv, snd_max); + } else { + /* + * Loss is likely to be congestion related. We have + * inferred a queue full state, so have shadow window + * react to loss as NewReno would. + */ + if (cdg_data->shadow_w > 0) + cdg_data->shadow_w = cdg_window_decrease(ccv, + cdg_data->shadow_w, RENO_BETA); + + CCV(ccv, snd_ssthresh) = ulmax(cdg_data->shadow_w, + cdg_window_decrease(ccv, CCV(ccv, snd_cwnd), + V_cdg_beta_loss)); + + cdg_data->window_incr = cdg_data->rtt_count = 0; + } + ENTER_RECOVERY(CCV(ccv, t_flags)); + break; + default: + newreno_cc_algo.cong_signal(ccv, signal_type); + break; + } +} + +/* + * Using a negative exponential probabilistic backoff so that sources with + * varying RTTs which share the same link will, on average, have the same + * probability of backoff over time. + * + * Prob_backoff = 1 - exp(-qtrend / V_cdg_exp_backoff_scale), where + * V_cdg_exp_backoff_scale is the average qtrend for the exponential backoff. + */ +static inline int +prob_backoff(long qtrend) +{ + int backoff, idx, p; + + backoff = (qtrend > ((MAXGRAD * V_cdg_exp_backoff_scale) << D_P_E)); + + if (!backoff) { + if (V_cdg_exp_backoff_scale > 1) + idx = (qtrend + V_cdg_exp_backoff_scale / 2) / + V_cdg_exp_backoff_scale; + else + idx = qtrend; + + /* Backoff probability proportional to rate of queue growth. */ + p = (INT_MAX / (1 << EXP_PREC)) * probexp[idx]; + backoff = (random() < p); + } + + return (backoff); +} + +static inline void +calc_moving_average(struct cdg *cdg_data, long qdiff_max, long qdiff_min) +{ + struct qdiff_sample *qds; + + ++cdg_data->num_samples; + if (cdg_data->num_samples > cdg_data->sample_q_size) { + /* Minimum RTT. */ + qds = STAILQ_FIRST(&cdg_data->qdiffmin_q); + cdg_data->min_qtrend = cdg_data->min_qtrend + + (qdiff_min - qds->qdiff) / cdg_data->sample_q_size; + STAILQ_REMOVE_HEAD(&cdg_data->qdiffmin_q, qdiff_lnk); + qds->qdiff = qdiff_min; + STAILQ_INSERT_TAIL(&cdg_data->qdiffmin_q, qds, qdiff_lnk); + + /* Maximum RTT. */ + qds = STAILQ_FIRST(&cdg_data->qdiffmax_q); + cdg_data->max_qtrend = cdg_data->max_qtrend + + (qdiff_max - qds->qdiff) / cdg_data->sample_q_size; + STAILQ_REMOVE_HEAD(&cdg_data->qdiffmax_q, qdiff_lnk); + qds->qdiff = qdiff_max; + STAILQ_INSERT_TAIL(&cdg_data->qdiffmax_q, qds, qdiff_lnk); + --cdg_data->num_samples; + } else { + qds = uma_zalloc(qdiffsample_zone, M_NOWAIT); + if (qds != NULL) { + cdg_data->min_qtrend = cdg_data->min_qtrend + + qdiff_min / cdg_data->sample_q_size; + qds->qdiff = qdiff_min; + STAILQ_INSERT_TAIL(&cdg_data->qdiffmin_q, qds, + qdiff_lnk); + } + + qds = uma_zalloc(qdiffsample_zone, M_NOWAIT); + if (qds) { + cdg_data->max_qtrend = cdg_data->max_qtrend + + qdiff_max / cdg_data->sample_q_size; + qds->qdiff = qdiff_max; + STAILQ_INSERT_TAIL(&cdg_data->qdiffmax_q, qds, + qdiff_lnk); + } + } +} + +static void +cdg_ack_received(struct cc_var *ccv, uint16_t ack_type) +{ + struct cdg *cdg_data; + struct ertt *e_t; + long qdiff_max, qdiff_min; + int congestion, new_measurement, slowstart; + + cdg_data = ccv->cc_data; + e_t = (struct ertt *)khelp_get_osd(CCV(ccv, osd), ertt_id); + new_measurement = e_t->flags & ERTT_NEW_MEASUREMENT; + congestion = 0; + cdg_data->maxrtt_in_rtt = imax(e_t->rtt, cdg_data->maxrtt_in_rtt); + cdg_data->minrtt_in_rtt = imin(e_t->rtt, cdg_data->minrtt_in_rtt); + + if (new_measurement) { + slowstart = (CCV(ccv, snd_cwnd) <= CCV(ccv, snd_ssthresh)); + /* + * Update smoothed gradient measurements. Since we are only + * using one measurement per RTT, use max or min rtt_in_rtt. + * This is also less noisy than a sample RTT measurement. Max + * RTT measurements can have trouble due to OS issues. + */ + if (cdg_data->maxrtt_in_prevrtt) { + qdiff_max = ((long)(cdg_data->maxrtt_in_rtt - + cdg_data->maxrtt_in_prevrtt) << D_P_E ); + qdiff_min = ((long)(cdg_data->minrtt_in_rtt - + cdg_data->minrtt_in_prevrtt) << D_P_E ); + + calc_moving_average(cdg_data, qdiff_max, qdiff_min); + + /* Probabilistic backoff with respect to gradient. */ + if (slowstart && qdiff_min > 0) + congestion = prob_backoff(qdiff_min); + else if (cdg_data->min_qtrend > 0) + congestion = prob_backoff(cdg_data->min_qtrend); + else if (slowstart && qdiff_max > 0) + congestion = prob_backoff(qdiff_max); + else if (cdg_data->max_qtrend > 0) + congestion = prob_backoff(cdg_data->max_qtrend); + + /* Update estimate of queue state. */ + if (cdg_data->min_qtrend > 0 && + cdg_data->max_qtrend <= 0) { + cdg_data->queue_state = CDG_Q_FULL; + } else if (cdg_data->min_qtrend >= 0 && + cdg_data->max_qtrend < 0) { + cdg_data->queue_state = CDG_Q_EMPTY; + cdg_data->shadow_w = 0; + } else if (cdg_data->min_qtrend > 0 && + cdg_data->max_qtrend > 0) { + cdg_data->queue_state = CDG_Q_RISING; + } else if (cdg_data->min_qtrend < 0 && + cdg_data->max_qtrend < 0) { + cdg_data->queue_state = CDG_Q_FALLING; + } + + if (cdg_data->min_qtrend < 0 || + cdg_data->max_qtrend < 0) + cdg_data->consec_cong_cnt = 0; + } + + cdg_data->minrtt_in_prevrtt = cdg_data->minrtt_in_rtt; + cdg_data->minrtt_in_rtt = INT_MAX; + cdg_data->maxrtt_in_prevrtt = cdg_data->maxrtt_in_rtt; + cdg_data->maxrtt_in_rtt = 0; + e_t->flags &= ~ERTT_NEW_MEASUREMENT; + } + + if (congestion) { + cdg_data->consec_cong_cnt++; + if (!IN_RECOVERY(CCV(ccv, t_flags))) { + if (cdg_data->consec_cong_cnt <= V_cdg_consec_cong) + cdg_cong_signal(ccv, CC_CDG_DELAY); + else + /* + * We have been backing off but the queue is not + * falling. Assume we are competing with + * loss-based flows and don't back off for the + * next V_cdg_hold_backoff RTT periods. + */ + if (cdg_data->consec_cong_cnt >= + V_cdg_consec_cong + V_cdg_hold_backoff) + cdg_data->consec_cong_cnt = 0; + + /* Won't see effect until 2nd RTT. */ + cdg_data->maxrtt_in_prevrtt = 0; + /* + * Resync shadow window in case we are competing with a + * loss based flow + */ + cdg_data->shadow_w = ulmax(CCV(ccv, snd_cwnd), + cdg_data->shadow_w); + } + } else if (ack_type == CC_ACK) + cdg_window_increase(ccv, new_measurement); +} + +/* When a vnet is created and being initialised, init the per-stack CDG vars. */ +VNET_SYSINIT(cdg_init_vnet, SI_SUB_PROTO_BEGIN, SI_ORDER_FIRST, + cdg_init_vnet, NULL); + +SYSCTL_DECL(_net_inet_tcp_cc_cdg); +SYSCTL_NODE(_net_inet_tcp_cc, OID_AUTO, cdg, CTLFLAG_RW, NULL, + "CAIA delay-gradient congestion control related settings"); + +SYSCTL_STRING(_net_inet_tcp_cc_cdg, OID_AUTO, version, + CTLFLAG_RD, CDG_VERSION, sizeof(CDG_VERSION) - 1, + "Current algorithm/implementation version number"); + +SYSCTL_VNET_UINT(_net_inet_tcp_cc_cdg, OID_AUTO, alpha_inc, + CTLFLAG_RW, &VNET_NAME(cdg_alpha_inc), 0, + "Increment the window increase factor alpha by 1 MSS segment every " + "alpha_inc RTTs during congestion avoidance mode."); + +SYSCTL_VNET_PROC(_net_inet_tcp_cc_cdg, OID_AUTO, beta_delay, + CTLTYPE_UINT|CTLFLAG_RW, &VNET_NAME(cdg_beta_delay), 70, + &cdg_beta_handler, "IU", + "Delay-based window decrease factor as a percentage " + "(on delay-based backoff, w = w * beta_delay / 100)"); + +SYSCTL_VNET_PROC(_net_inet_tcp_cc_cdg, OID_AUTO, beta_loss, + CTLTYPE_UINT|CTLFLAG_RW, &VNET_NAME(cdg_beta_loss), 50, + &cdg_beta_handler, "IU", + "Loss-based window decrease factor as a percentage " + "(on loss-based backoff, w = w * beta_loss / 100)"); + +SYSCTL_VNET_PROC(_net_inet_tcp_cc_cdg, OID_AUTO, exp_backoff_scale, + CTLTYPE_UINT|CTLFLAG_RW, &VNET_NAME(cdg_exp_backoff_scale), 2, + &cdg_exp_backoff_scale_handler, "IU", + "Scaling parameter for the probabilistic exponential backoff"); + +SYSCTL_VNET_UINT(_net_inet_tcp_cc_cdg, OID_AUTO, smoothing_factor, + CTLFLAG_RW, &VNET_NAME(cdg_smoothing_factor), 8, + "Number of samples used for moving average smoothing (0 = no smoothing)"); + +SYSCTL_VNET_UINT(_net_inet_tcp_cc_cdg, OID_AUTO, loss_compete_consec_cong, + CTLFLAG_RW, &VNET_NAME(cdg_consec_cong), 5, + "Number of consecutive delay-gradient based congestion episodes which will " + "trigger loss based CC compatibility"); + +SYSCTL_VNET_UINT(_net_inet_tcp_cc_cdg, OID_AUTO, loss_compete_hold_backoff, + CTLFLAG_RW, &VNET_NAME(cdg_hold_backoff), 5, + "Number of consecutive delay-gradient based congestion episodes to hold " + "the window backoff for loss based CC compatibility"); + +DECLARE_CC_MODULE(cdg, &cdg_cc_algo); + +MODULE_DEPEND(cdg, ertt, 1, 1, 1); |
