Greg Kroah-Hartman | b244131 | 2017-11-01 15:07:57 +0100 | [diff] [blame] | 1 | /* SPDX-License-Identifier: GPL-2.0 */ |
Thomas Graf | a783474 | 2005-11-05 21:14:03 +0100 | [diff] [blame] | 2 | #ifndef __NET_SCHED_RED_H |
| 3 | #define __NET_SCHED_RED_H |
| 4 | |
Thomas Graf | a783474 | 2005-11-05 21:14:03 +0100 | [diff] [blame] | 5 | #include <linux/types.h> |
Paul Gortmaker | 187f188 | 2011-11-23 20:12:59 -0500 | [diff] [blame] | 6 | #include <linux/bug.h> |
Thomas Graf | a783474 | 2005-11-05 21:14:03 +0100 | [diff] [blame] | 7 | #include <net/pkt_sched.h> |
| 8 | #include <net/inet_ecn.h> |
| 9 | #include <net/dsfield.h> |
Eric Dumazet | 8af2a21 | 2011-12-08 06:06:03 +0000 | [diff] [blame] | 10 | #include <linux/reciprocal_div.h> |
Thomas Graf | a783474 | 2005-11-05 21:14:03 +0100 | [diff] [blame] | 11 | |
| 12 | /* Random Early Detection (RED) algorithm. |
| 13 | ======================================= |
| 14 | |
| 15 | Source: Sally Floyd and Van Jacobson, "Random Early Detection Gateways |
| 16 | for Congestion Avoidance", 1993, IEEE/ACM Transactions on Networking. |
| 17 | |
| 18 | This file codes a "divisionless" version of RED algorithm |
| 19 | as written down in Fig.17 of the paper. |
| 20 | |
| 21 | Short description. |
| 22 | ------------------ |
| 23 | |
| 24 | When a new packet arrives we calculate the average queue length: |
| 25 | |
| 26 | avg = (1-W)*avg + W*current_queue_len, |
| 27 | |
| 28 | W is the filter time constant (chosen as 2^(-Wlog)), it controls |
| 29 | the inertia of the algorithm. To allow larger bursts, W should be |
| 30 | decreased. |
| 31 | |
| 32 | if (avg > th_max) -> packet marked (dropped). |
| 33 | if (avg < th_min) -> packet passes. |
| 34 | if (th_min < avg < th_max) we calculate probability: |
| 35 | |
| 36 | Pb = max_P * (avg - th_min)/(th_max-th_min) |
| 37 | |
| 38 | and mark (drop) packet with this probability. |
| 39 | Pb changes from 0 (at avg==th_min) to max_P (avg==th_max). |
| 40 | max_P should be small (not 1), usually 0.01..0.02 is good value. |
| 41 | |
| 42 | max_P is chosen as a number, so that max_P/(th_max-th_min) |
| 43 | is a negative power of two in order arithmetics to contain |
| 44 | only shifts. |
| 45 | |
| 46 | |
| 47 | Parameters, settable by user: |
| 48 | ----------------------------- |
| 49 | |
| 50 | qth_min - bytes (should be < qth_max/2) |
| 51 | qth_max - bytes (should be at least 2*qth_min and less limit) |
| 52 | Wlog - bits (<32) log(1/W). |
| 53 | Plog - bits (<32) |
| 54 | |
| 55 | Plog is related to max_P by formula: |
| 56 | |
| 57 | max_P = (qth_max-qth_min)/2^Plog; |
| 58 | |
| 59 | F.e. if qth_max=128K and qth_min=32K, then Plog=22 |
| 60 | corresponds to max_P=0.02 |
| 61 | |
| 62 | Scell_log |
| 63 | Stab |
| 64 | |
| 65 | Lookup table for log((1-W)^(t/t_ave). |
| 66 | |
| 67 | |
| 68 | NOTES: |
| 69 | |
| 70 | Upper bound on W. |
| 71 | ----------------- |
| 72 | |
| 73 | If you want to allow bursts of L packets of size S, |
| 74 | you should choose W: |
| 75 | |
| 76 | L + 1 - th_min/S < (1-(1-W)^L)/W |
| 77 | |
| 78 | th_min/S = 32 th_min/S = 4 |
| 79 | |
| 80 | log(W) L |
| 81 | -1 33 |
| 82 | -2 35 |
| 83 | -3 39 |
| 84 | -4 46 |
| 85 | -5 57 |
| 86 | -6 75 |
| 87 | -7 101 |
| 88 | -8 135 |
| 89 | -9 190 |
| 90 | etc. |
| 91 | */ |
| 92 | |
Eric Dumazet | 8af2a21 | 2011-12-08 06:06:03 +0000 | [diff] [blame] | 93 | /* |
| 94 | * Adaptative RED : An Algorithm for Increasing the Robustness of RED's AQM |
| 95 | * (Sally FLoyd, Ramakrishna Gummadi, and Scott Shenker) August 2001 |
| 96 | * |
| 97 | * Every 500 ms: |
| 98 | * if (avg > target and max_p <= 0.5) |
| 99 | * increase max_p : max_p += alpha; |
| 100 | * else if (avg < target and max_p >= 0.01) |
| 101 | * decrease max_p : max_p *= beta; |
| 102 | * |
| 103 | * target :[qth_min + 0.4*(qth_min - qth_max), |
| 104 | * qth_min + 0.6*(qth_min - qth_max)]. |
| 105 | * alpha : min(0.01, max_p / 4) |
| 106 | * beta : 0.9 |
| 107 | * max_P is a Q0.32 fixed point number (with 32 bits mantissa) |
| 108 | * max_P between 0.01 and 0.5 (1% - 50%) [ Its no longer a negative power of two ] |
| 109 | */ |
| 110 | #define RED_ONE_PERCENT ((u32)DIV_ROUND_CLOSEST(1ULL<<32, 100)) |
| 111 | |
| 112 | #define MAX_P_MIN (1 * RED_ONE_PERCENT) |
| 113 | #define MAX_P_MAX (50 * RED_ONE_PERCENT) |
| 114 | #define MAX_P_ALPHA(val) min(MAX_P_MIN, val / 4) |
| 115 | |
Thomas Graf | a783474 | 2005-11-05 21:14:03 +0100 | [diff] [blame] | 116 | #define RED_STAB_SIZE 256 |
| 117 | #define RED_STAB_MASK (RED_STAB_SIZE - 1) |
| 118 | |
Eric Dumazet | fd2c3ef | 2009-11-03 03:26:03 +0000 | [diff] [blame] | 119 | struct red_stats { |
Thomas Graf | a783474 | 2005-11-05 21:14:03 +0100 | [diff] [blame] | 120 | u32 prob_drop; /* Early probability drops */ |
| 121 | u32 prob_mark; /* Early probability marks */ |
| 122 | u32 forced_drop; /* Forced drops, qavg > max_thresh */ |
| 123 | u32 forced_mark; /* Forced marks, qavg > max_thresh */ |
| 124 | u32 pdrop; /* Drops due to queue limits */ |
| 125 | u32 other; /* Drops due to drop() calls */ |
Thomas Graf | a783474 | 2005-11-05 21:14:03 +0100 | [diff] [blame] | 126 | }; |
| 127 | |
Eric Dumazet | fd2c3ef | 2009-11-03 03:26:03 +0000 | [diff] [blame] | 128 | struct red_parms { |
Thomas Graf | a783474 | 2005-11-05 21:14:03 +0100 | [diff] [blame] | 129 | /* Parameters */ |
Eric Dumazet | 8af2a21 | 2011-12-08 06:06:03 +0000 | [diff] [blame] | 130 | u32 qth_min; /* Min avg length threshold: Wlog scaled */ |
| 131 | u32 qth_max; /* Max avg length threshold: Wlog scaled */ |
Thomas Graf | a783474 | 2005-11-05 21:14:03 +0100 | [diff] [blame] | 132 | u32 Scell_max; |
Eric Dumazet | 8af2a21 | 2011-12-08 06:06:03 +0000 | [diff] [blame] | 133 | u32 max_P; /* probability, [0 .. 1.0] 32 scaled */ |
Hannes Frederic Sowa | 809fa97 | 2014-01-22 02:29:41 +0100 | [diff] [blame] | 134 | /* reciprocal_value(max_P / qth_delta) */ |
| 135 | struct reciprocal_value max_P_reciprocal; |
Eric Dumazet | 8af2a21 | 2011-12-08 06:06:03 +0000 | [diff] [blame] | 136 | u32 qth_delta; /* max_th - min_th */ |
| 137 | u32 target_min; /* min_th + 0.4*(max_th - min_th) */ |
| 138 | u32 target_max; /* min_th + 0.6*(max_th - min_th) */ |
Thomas Graf | a783474 | 2005-11-05 21:14:03 +0100 | [diff] [blame] | 139 | u8 Scell_log; |
| 140 | u8 Wlog; /* log(W) */ |
| 141 | u8 Plog; /* random number bits */ |
| 142 | u8 Stab[RED_STAB_SIZE]; |
Eric Dumazet | eeca668 | 2012-01-05 02:25:16 +0000 | [diff] [blame] | 143 | }; |
Thomas Graf | a783474 | 2005-11-05 21:14:03 +0100 | [diff] [blame] | 144 | |
Eric Dumazet | eeca668 | 2012-01-05 02:25:16 +0000 | [diff] [blame] | 145 | struct red_vars { |
Thomas Graf | a783474 | 2005-11-05 21:14:03 +0100 | [diff] [blame] | 146 | /* Variables */ |
| 147 | int qcount; /* Number of packets since last random |
| 148 | number generation */ |
| 149 | u32 qR; /* Cached random number */ |
| 150 | |
Eric Dumazet | 8af2a21 | 2011-12-08 06:06:03 +0000 | [diff] [blame] | 151 | unsigned long qavg; /* Average queue length: Wlog scaled */ |
Eric Dumazet | ea6a5d3 | 2011-11-30 12:10:53 +0000 | [diff] [blame] | 152 | ktime_t qidlestart; /* Start of current idle period */ |
Thomas Graf | a783474 | 2005-11-05 21:14:03 +0100 | [diff] [blame] | 153 | }; |
| 154 | |
Eric Dumazet | 8af2a21 | 2011-12-08 06:06:03 +0000 | [diff] [blame] | 155 | static inline u32 red_maxp(u8 Plog) |
Thomas Graf | a783474 | 2005-11-05 21:14:03 +0100 | [diff] [blame] | 156 | { |
Eric Dumazet | 8af2a21 | 2011-12-08 06:06:03 +0000 | [diff] [blame] | 157 | return Plog < 32 ? (~0U >> Plog) : ~0U; |
Thomas Graf | a783474 | 2005-11-05 21:14:03 +0100 | [diff] [blame] | 158 | } |
| 159 | |
Eric Dumazet | eeca668 | 2012-01-05 02:25:16 +0000 | [diff] [blame] | 160 | static inline void red_set_vars(struct red_vars *v) |
| 161 | { |
| 162 | /* Reset average queue length, the value is strictly bound |
| 163 | * to the parameters below, reseting hurts a bit but leaving |
| 164 | * it might result in an unreasonable qavg for a while. --TGR |
| 165 | */ |
| 166 | v->qavg = 0; |
| 167 | |
| 168 | v->qcount = -1; |
| 169 | } |
Eric Dumazet | 8af2a21 | 2011-12-08 06:06:03 +0000 | [diff] [blame] | 170 | |
Nogah Frankel | 8afa10c | 2017-12-04 13:31:11 +0200 | [diff] [blame] | 171 | static inline bool red_check_params(u32 qth_min, u32 qth_max, u8 Wlog) |
| 172 | { |
| 173 | if (fls(qth_min) + Wlog > 32) |
| 174 | return false; |
| 175 | if (fls(qth_max) + Wlog > 32) |
| 176 | return false; |
| 177 | if (qth_max < qth_min) |
| 178 | return false; |
| 179 | return true; |
| 180 | } |
| 181 | |
Thomas Graf | a783474 | 2005-11-05 21:14:03 +0100 | [diff] [blame] | 182 | static inline void red_set_parms(struct red_parms *p, |
| 183 | u32 qth_min, u32 qth_max, u8 Wlog, u8 Plog, |
Eric Dumazet | a73ed26 | 2011-12-09 02:46:45 +0000 | [diff] [blame] | 184 | u8 Scell_log, u8 *stab, u32 max_P) |
Thomas Graf | a783474 | 2005-11-05 21:14:03 +0100 | [diff] [blame] | 185 | { |
Eric Dumazet | 8af2a21 | 2011-12-08 06:06:03 +0000 | [diff] [blame] | 186 | int delta = qth_max - qth_min; |
Eric Dumazet | a73ed26 | 2011-12-09 02:46:45 +0000 | [diff] [blame] | 187 | u32 max_p_delta; |
Eric Dumazet | 8af2a21 | 2011-12-08 06:06:03 +0000 | [diff] [blame] | 188 | |
Thomas Graf | a783474 | 2005-11-05 21:14:03 +0100 | [diff] [blame] | 189 | p->qth_min = qth_min << Wlog; |
| 190 | p->qth_max = qth_max << Wlog; |
| 191 | p->Wlog = Wlog; |
| 192 | p->Plog = Plog; |
Nogah Frankel | 5c47220 | 2017-12-04 13:31:10 +0200 | [diff] [blame] | 193 | if (delta <= 0) |
Eric Dumazet | 8af2a21 | 2011-12-08 06:06:03 +0000 | [diff] [blame] | 194 | delta = 1; |
| 195 | p->qth_delta = delta; |
Eric Dumazet | a73ed26 | 2011-12-09 02:46:45 +0000 | [diff] [blame] | 196 | if (!max_P) { |
| 197 | max_P = red_maxp(Plog); |
| 198 | max_P *= delta; /* max_P = (qth_max - qth_min)/2^Plog */ |
| 199 | } |
| 200 | p->max_P = max_P; |
| 201 | max_p_delta = max_P / delta; |
| 202 | max_p_delta = max(max_p_delta, 1U); |
| 203 | p->max_P_reciprocal = reciprocal_value(max_p_delta); |
Eric Dumazet | 8af2a21 | 2011-12-08 06:06:03 +0000 | [diff] [blame] | 204 | |
| 205 | /* RED Adaptative target : |
| 206 | * [min_th + 0.4*(min_th - max_th), |
| 207 | * min_th + 0.6*(min_th - max_th)]. |
| 208 | */ |
| 209 | delta /= 5; |
| 210 | p->target_min = qth_min + 2*delta; |
| 211 | p->target_max = qth_min + 3*delta; |
| 212 | |
Thomas Graf | a783474 | 2005-11-05 21:14:03 +0100 | [diff] [blame] | 213 | p->Scell_log = Scell_log; |
| 214 | p->Scell_max = (255 << Scell_log); |
| 215 | |
Eric Dumazet | ddecf0f | 2012-01-06 06:31:44 +0000 | [diff] [blame] | 216 | if (stab) |
| 217 | memcpy(p->Stab, stab, sizeof(p->Stab)); |
Thomas Graf | a783474 | 2005-11-05 21:14:03 +0100 | [diff] [blame] | 218 | } |
| 219 | |
Eric Dumazet | eeca668 | 2012-01-05 02:25:16 +0000 | [diff] [blame] | 220 | static inline int red_is_idling(const struct red_vars *v) |
Thomas Graf | a783474 | 2005-11-05 21:14:03 +0100 | [diff] [blame] | 221 | { |
Thomas Gleixner | 2456e85 | 2016-12-25 11:38:40 +0100 | [diff] [blame] | 222 | return v->qidlestart != 0; |
Thomas Graf | a783474 | 2005-11-05 21:14:03 +0100 | [diff] [blame] | 223 | } |
| 224 | |
Eric Dumazet | eeca668 | 2012-01-05 02:25:16 +0000 | [diff] [blame] | 225 | static inline void red_start_of_idle_period(struct red_vars *v) |
Thomas Graf | a783474 | 2005-11-05 21:14:03 +0100 | [diff] [blame] | 226 | { |
Eric Dumazet | eeca668 | 2012-01-05 02:25:16 +0000 | [diff] [blame] | 227 | v->qidlestart = ktime_get(); |
Thomas Graf | a783474 | 2005-11-05 21:14:03 +0100 | [diff] [blame] | 228 | } |
| 229 | |
Eric Dumazet | eeca668 | 2012-01-05 02:25:16 +0000 | [diff] [blame] | 230 | static inline void red_end_of_idle_period(struct red_vars *v) |
Thomas Graf | a783474 | 2005-11-05 21:14:03 +0100 | [diff] [blame] | 231 | { |
Thomas Gleixner | 2456e85 | 2016-12-25 11:38:40 +0100 | [diff] [blame] | 232 | v->qidlestart = 0; |
Thomas Graf | a783474 | 2005-11-05 21:14:03 +0100 | [diff] [blame] | 233 | } |
| 234 | |
Eric Dumazet | eeca668 | 2012-01-05 02:25:16 +0000 | [diff] [blame] | 235 | static inline void red_restart(struct red_vars *v) |
Thomas Graf | a783474 | 2005-11-05 21:14:03 +0100 | [diff] [blame] | 236 | { |
Eric Dumazet | eeca668 | 2012-01-05 02:25:16 +0000 | [diff] [blame] | 237 | red_end_of_idle_period(v); |
| 238 | v->qavg = 0; |
| 239 | v->qcount = -1; |
Thomas Graf | a783474 | 2005-11-05 21:14:03 +0100 | [diff] [blame] | 240 | } |
| 241 | |
Eric Dumazet | eeca668 | 2012-01-05 02:25:16 +0000 | [diff] [blame] | 242 | static inline unsigned long red_calc_qavg_from_idle_time(const struct red_parms *p, |
| 243 | const struct red_vars *v) |
Thomas Graf | a783474 | 2005-11-05 21:14:03 +0100 | [diff] [blame] | 244 | { |
Eric Dumazet | eeca668 | 2012-01-05 02:25:16 +0000 | [diff] [blame] | 245 | s64 delta = ktime_us_delta(ktime_get(), v->qidlestart); |
Eric Dumazet | ea6a5d3 | 2011-11-30 12:10:53 +0000 | [diff] [blame] | 246 | long us_idle = min_t(s64, delta, p->Scell_max); |
Thomas Graf | a783474 | 2005-11-05 21:14:03 +0100 | [diff] [blame] | 247 | int shift; |
| 248 | |
Thomas Graf | a783474 | 2005-11-05 21:14:03 +0100 | [diff] [blame] | 249 | /* |
| 250 | * The problem: ideally, average length queue recalcultion should |
| 251 | * be done over constant clock intervals. This is too expensive, so |
| 252 | * that the calculation is driven by outgoing packets. |
| 253 | * When the queue is idle we have to model this clock by hand. |
| 254 | * |
| 255 | * SF+VJ proposed to "generate": |
| 256 | * |
| 257 | * m = idletime / (average_pkt_size / bandwidth) |
| 258 | * |
| 259 | * dummy packets as a burst after idle time, i.e. |
| 260 | * |
David Ward | 4362aaf | 2012-04-16 03:17:22 +0000 | [diff] [blame] | 261 | * v->qavg *= (1-W)^m |
Thomas Graf | a783474 | 2005-11-05 21:14:03 +0100 | [diff] [blame] | 262 | * |
| 263 | * This is an apparently overcomplicated solution (f.e. we have to |
| 264 | * precompute a table to make this calculation in reasonable time) |
| 265 | * I believe that a simpler model may be used here, |
| 266 | * but it is field for experiments. |
| 267 | */ |
| 268 | |
| 269 | shift = p->Stab[(us_idle >> p->Scell_log) & RED_STAB_MASK]; |
| 270 | |
| 271 | if (shift) |
Eric Dumazet | eeca668 | 2012-01-05 02:25:16 +0000 | [diff] [blame] | 272 | return v->qavg >> shift; |
Thomas Graf | a783474 | 2005-11-05 21:14:03 +0100 | [diff] [blame] | 273 | else { |
| 274 | /* Approximate initial part of exponent with linear function: |
| 275 | * |
| 276 | * (1-W)^m ~= 1-mW + ... |
| 277 | * |
| 278 | * Seems, it is the best solution to |
| 279 | * problem of too coarse exponent tabulation. |
| 280 | */ |
Eric Dumazet | eeca668 | 2012-01-05 02:25:16 +0000 | [diff] [blame] | 281 | us_idle = (v->qavg * (u64)us_idle) >> p->Scell_log; |
Thomas Graf | a783474 | 2005-11-05 21:14:03 +0100 | [diff] [blame] | 282 | |
Eric Dumazet | eeca668 | 2012-01-05 02:25:16 +0000 | [diff] [blame] | 283 | if (us_idle < (v->qavg >> 1)) |
| 284 | return v->qavg - us_idle; |
Thomas Graf | a783474 | 2005-11-05 21:14:03 +0100 | [diff] [blame] | 285 | else |
Eric Dumazet | eeca668 | 2012-01-05 02:25:16 +0000 | [diff] [blame] | 286 | return v->qavg >> 1; |
Thomas Graf | a783474 | 2005-11-05 21:14:03 +0100 | [diff] [blame] | 287 | } |
| 288 | } |
| 289 | |
Eric Dumazet | 8af2a21 | 2011-12-08 06:06:03 +0000 | [diff] [blame] | 290 | static inline unsigned long red_calc_qavg_no_idle_time(const struct red_parms *p, |
Eric Dumazet | eeca668 | 2012-01-05 02:25:16 +0000 | [diff] [blame] | 291 | const struct red_vars *v, |
Thomas Graf | a783474 | 2005-11-05 21:14:03 +0100 | [diff] [blame] | 292 | unsigned int backlog) |
| 293 | { |
| 294 | /* |
David Ward | 4362aaf | 2012-04-16 03:17:22 +0000 | [diff] [blame] | 295 | * NOTE: v->qavg is fixed point number with point at Wlog. |
Thomas Graf | a783474 | 2005-11-05 21:14:03 +0100 | [diff] [blame] | 296 | * The formula below is equvalent to floating point |
| 297 | * version: |
| 298 | * |
| 299 | * qavg = qavg*(1-W) + backlog*W; |
| 300 | * |
| 301 | * --ANK (980924) |
| 302 | */ |
Eric Dumazet | eeca668 | 2012-01-05 02:25:16 +0000 | [diff] [blame] | 303 | return v->qavg + (backlog - (v->qavg >> p->Wlog)); |
Thomas Graf | a783474 | 2005-11-05 21:14:03 +0100 | [diff] [blame] | 304 | } |
| 305 | |
Eric Dumazet | 8af2a21 | 2011-12-08 06:06:03 +0000 | [diff] [blame] | 306 | static inline unsigned long red_calc_qavg(const struct red_parms *p, |
Eric Dumazet | eeca668 | 2012-01-05 02:25:16 +0000 | [diff] [blame] | 307 | const struct red_vars *v, |
Thomas Graf | a783474 | 2005-11-05 21:14:03 +0100 | [diff] [blame] | 308 | unsigned int backlog) |
| 309 | { |
Eric Dumazet | eeca668 | 2012-01-05 02:25:16 +0000 | [diff] [blame] | 310 | if (!red_is_idling(v)) |
| 311 | return red_calc_qavg_no_idle_time(p, v, backlog); |
Thomas Graf | a783474 | 2005-11-05 21:14:03 +0100 | [diff] [blame] | 312 | else |
Eric Dumazet | eeca668 | 2012-01-05 02:25:16 +0000 | [diff] [blame] | 313 | return red_calc_qavg_from_idle_time(p, v); |
Thomas Graf | a783474 | 2005-11-05 21:14:03 +0100 | [diff] [blame] | 314 | } |
| 315 | |
Eric Dumazet | 8af2a21 | 2011-12-08 06:06:03 +0000 | [diff] [blame] | 316 | |
| 317 | static inline u32 red_random(const struct red_parms *p) |
Thomas Graf | a783474 | 2005-11-05 21:14:03 +0100 | [diff] [blame] | 318 | { |
Aruna-Hewapathirane | 63862b5 | 2014-01-11 07:15:59 -0500 | [diff] [blame] | 319 | return reciprocal_divide(prandom_u32(), p->max_P_reciprocal); |
Thomas Graf | a783474 | 2005-11-05 21:14:03 +0100 | [diff] [blame] | 320 | } |
| 321 | |
Eric Dumazet | eeca668 | 2012-01-05 02:25:16 +0000 | [diff] [blame] | 322 | static inline int red_mark_probability(const struct red_parms *p, |
| 323 | const struct red_vars *v, |
| 324 | unsigned long qavg) |
Thomas Graf | a783474 | 2005-11-05 21:14:03 +0100 | [diff] [blame] | 325 | { |
| 326 | /* The formula used below causes questions. |
| 327 | |
Eric Dumazet | 8af2a21 | 2011-12-08 06:06:03 +0000 | [diff] [blame] | 328 | OK. qR is random number in the interval |
| 329 | (0..1/max_P)*(qth_max-qth_min) |
Thomas Graf | a783474 | 2005-11-05 21:14:03 +0100 | [diff] [blame] | 330 | i.e. 0..(2^Plog). If we used floating point |
| 331 | arithmetics, it would be: (2^Plog)*rnd_num, |
| 332 | where rnd_num is less 1. |
| 333 | |
| 334 | Taking into account, that qavg have fixed |
Eric Dumazet | 8af2a21 | 2011-12-08 06:06:03 +0000 | [diff] [blame] | 335 | point at Wlog, two lines |
Thomas Graf | a783474 | 2005-11-05 21:14:03 +0100 | [diff] [blame] | 336 | below have the following floating point equivalent: |
| 337 | |
| 338 | max_P*(qavg - qth_min)/(qth_max-qth_min) < rnd/qcount |
| 339 | |
| 340 | Any questions? --ANK (980924) |
| 341 | */ |
Eric Dumazet | eeca668 | 2012-01-05 02:25:16 +0000 | [diff] [blame] | 342 | return !(((qavg - p->qth_min) >> p->Wlog) * v->qcount < v->qR); |
Thomas Graf | a783474 | 2005-11-05 21:14:03 +0100 | [diff] [blame] | 343 | } |
| 344 | |
| 345 | enum { |
| 346 | RED_BELOW_MIN_THRESH, |
| 347 | RED_BETWEEN_TRESH, |
| 348 | RED_ABOVE_MAX_TRESH, |
| 349 | }; |
| 350 | |
Eric Dumazet | eeca668 | 2012-01-05 02:25:16 +0000 | [diff] [blame] | 351 | static inline int red_cmp_thresh(const struct red_parms *p, unsigned long qavg) |
Thomas Graf | a783474 | 2005-11-05 21:14:03 +0100 | [diff] [blame] | 352 | { |
| 353 | if (qavg < p->qth_min) |
| 354 | return RED_BELOW_MIN_THRESH; |
| 355 | else if (qavg >= p->qth_max) |
| 356 | return RED_ABOVE_MAX_TRESH; |
| 357 | else |
| 358 | return RED_BETWEEN_TRESH; |
| 359 | } |
| 360 | |
| 361 | enum { |
| 362 | RED_DONT_MARK, |
| 363 | RED_PROB_MARK, |
| 364 | RED_HARD_MARK, |
| 365 | }; |
| 366 | |
Eric Dumazet | eeca668 | 2012-01-05 02:25:16 +0000 | [diff] [blame] | 367 | static inline int red_action(const struct red_parms *p, |
| 368 | struct red_vars *v, |
| 369 | unsigned long qavg) |
Thomas Graf | a783474 | 2005-11-05 21:14:03 +0100 | [diff] [blame] | 370 | { |
| 371 | switch (red_cmp_thresh(p, qavg)) { |
| 372 | case RED_BELOW_MIN_THRESH: |
Eric Dumazet | eeca668 | 2012-01-05 02:25:16 +0000 | [diff] [blame] | 373 | v->qcount = -1; |
Thomas Graf | a783474 | 2005-11-05 21:14:03 +0100 | [diff] [blame] | 374 | return RED_DONT_MARK; |
| 375 | |
| 376 | case RED_BETWEEN_TRESH: |
Eric Dumazet | eeca668 | 2012-01-05 02:25:16 +0000 | [diff] [blame] | 377 | if (++v->qcount) { |
| 378 | if (red_mark_probability(p, v, qavg)) { |
| 379 | v->qcount = 0; |
| 380 | v->qR = red_random(p); |
Thomas Graf | a783474 | 2005-11-05 21:14:03 +0100 | [diff] [blame] | 381 | return RED_PROB_MARK; |
| 382 | } |
| 383 | } else |
Eric Dumazet | eeca668 | 2012-01-05 02:25:16 +0000 | [diff] [blame] | 384 | v->qR = red_random(p); |
Thomas Graf | a783474 | 2005-11-05 21:14:03 +0100 | [diff] [blame] | 385 | |
| 386 | return RED_DONT_MARK; |
| 387 | |
| 388 | case RED_ABOVE_MAX_TRESH: |
Eric Dumazet | eeca668 | 2012-01-05 02:25:16 +0000 | [diff] [blame] | 389 | v->qcount = -1; |
Thomas Graf | a783474 | 2005-11-05 21:14:03 +0100 | [diff] [blame] | 390 | return RED_HARD_MARK; |
| 391 | } |
| 392 | |
| 393 | BUG(); |
| 394 | return RED_DONT_MARK; |
| 395 | } |
| 396 | |
Eric Dumazet | eeca668 | 2012-01-05 02:25:16 +0000 | [diff] [blame] | 397 | static inline void red_adaptative_algo(struct red_parms *p, struct red_vars *v) |
Eric Dumazet | 8af2a21 | 2011-12-08 06:06:03 +0000 | [diff] [blame] | 398 | { |
| 399 | unsigned long qavg; |
| 400 | u32 max_p_delta; |
| 401 | |
Eric Dumazet | eeca668 | 2012-01-05 02:25:16 +0000 | [diff] [blame] | 402 | qavg = v->qavg; |
| 403 | if (red_is_idling(v)) |
| 404 | qavg = red_calc_qavg_from_idle_time(p, v); |
Eric Dumazet | 8af2a21 | 2011-12-08 06:06:03 +0000 | [diff] [blame] | 405 | |
David Ward | 4362aaf | 2012-04-16 03:17:22 +0000 | [diff] [blame] | 406 | /* v->qavg is fixed point number with point at Wlog */ |
Eric Dumazet | 8af2a21 | 2011-12-08 06:06:03 +0000 | [diff] [blame] | 407 | qavg >>= p->Wlog; |
| 408 | |
| 409 | if (qavg > p->target_max && p->max_P <= MAX_P_MAX) |
| 410 | p->max_P += MAX_P_ALPHA(p->max_P); /* maxp = maxp + alpha */ |
| 411 | else if (qavg < p->target_min && p->max_P >= MAX_P_MIN) |
| 412 | p->max_P = (p->max_P/10)*9; /* maxp = maxp * Beta */ |
| 413 | |
| 414 | max_p_delta = DIV_ROUND_CLOSEST(p->max_P, p->qth_delta); |
Eric Dumazet | a73ed26 | 2011-12-09 02:46:45 +0000 | [diff] [blame] | 415 | max_p_delta = max(max_p_delta, 1U); |
Eric Dumazet | 8af2a21 | 2011-12-08 06:06:03 +0000 | [diff] [blame] | 416 | p->max_P_reciprocal = reciprocal_value(max_p_delta); |
| 417 | } |
Thomas Graf | a783474 | 2005-11-05 21:14:03 +0100 | [diff] [blame] | 418 | #endif |