net/sched/sch

/* [<][>][^][v][top][bottom][index][help] */
This source file includes following definitions.
pie_params_init
pie_vars_init
drop_early
pie_qdisc_enqueue
pie_change
pie_process_dequeue
calculate_probability
pie_timer
pie_init
pie_dump
pie_dump_stats
pie_qdisc_dequeue
pie_reset
pie_destroy
pie_module_init
pie_module_exit
   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /* Copyright (C) 2013 Cisco Systems, Inc, 2013.
   3  *
   4  * Author: Vijay Subramanian <vijaynsu@cisco.com>
   5  * Author: Mythili Prabhu <mysuryan@cisco.com>
   6  *
   7  * ECN support is added by Naeem Khademi <naeemk@ifi.uio.no>
   8  * University of Oslo, Norway.
   9  *
  10  * References:
  11  * RFC 8033: https://tools.ietf.org/html/rfc8033
  12  */
  13 
  14 #include <linux/module.h>
  15 #include <linux/slab.h>
  16 #include <linux/types.h>
  17 #include <linux/kernel.h>
  18 #include <linux/errno.h>
  19 #include <linux/skbuff.h>
  20 #include <net/pkt_sched.h>
  21 #include <net/inet_ecn.h>
  22 
  23 #define QUEUE_THRESHOLD 16384
  24 #define DQCOUNT_INVALID -1
  25 #define MAX_PROB 0xffffffffffffffff
  26 #define PIE_SCALE 8
  27 
  28 /* parameters used */
  29 struct pie_params {
  30         psched_time_t target;   /* user specified target delay in pschedtime */
  31         u32 tupdate;            /* timer frequency (in jiffies) */
  32         u32 limit;              /* number of packets that can be enqueued */
  33         u32 alpha;              /* alpha and beta are between 0 and 32 */
  34         u32 beta;               /* and are used for shift relative to 1 */
  35         bool ecn;               /* true if ecn is enabled */
  36         bool bytemode;          /* to scale drop early prob based on pkt size */
  37 };
  38 
  39 /* variables used */
  40 struct pie_vars {
  41         u64 prob;               /* probability but scaled by u64 limit. */
  42         psched_time_t burst_time;
  43         psched_time_t qdelay;
  44         psched_time_t qdelay_old;
  45         u64 dq_count;           /* measured in bytes */
  46         psched_time_t dq_tstamp;        /* drain rate */
  47         u64 accu_prob;          /* accumulated drop probability */
  48         u32 avg_dq_rate;        /* bytes per pschedtime tick,scaled */
  49         u32 qlen_old;           /* in bytes */
  50         u8 accu_prob_overflows; /* overflows of accu_prob */
  51 };
  52 
  53 /* statistics gathering */
  54 struct pie_stats {
  55         u32 packets_in;         /* total number of packets enqueued */
  56         u32 dropped;            /* packets dropped due to pie_action */
  57         u32 overlimit;          /* dropped due to lack of space in queue */
  58         u32 maxq;               /* maximum queue size */
  59         u32 ecn_mark;           /* packets marked with ECN */
  60 };
  61 
  62 /* private data for the Qdisc */
  63 struct pie_sched_data {
  64         struct pie_params params;
  65         struct pie_vars vars;
  66         struct pie_stats stats;
  67         struct timer_list adapt_timer;
  68         struct Qdisc *sch;
  69 };
  70 
  71 static void pie_params_init(struct pie_params *params)
  72 {
  73         params->alpha = 2;
  74         params->beta = 20;
  75         params->tupdate = usecs_to_jiffies(15 * USEC_PER_MSEC); /* 15 ms */
  76         params->limit = 1000;   /* default of 1000 packets */
  77         params->target = PSCHED_NS2TICKS(15 * NSEC_PER_MSEC);   /* 15 ms */
  78         params->ecn = false;
  79         params->bytemode = false;
  80 }
  81 
  82 static void pie_vars_init(struct pie_vars *vars)
  83 {
  84         vars->dq_count = DQCOUNT_INVALID;
  85         vars->accu_prob = 0;
  86         vars->avg_dq_rate = 0;
  87         /* default of 150 ms in pschedtime */
  88         vars->burst_time = PSCHED_NS2TICKS(150 * NSEC_PER_MSEC);
  89         vars->accu_prob_overflows = 0;
  90 }
  91 
  92 static bool drop_early(struct Qdisc *sch, u32 packet_size)
  93 {
  94         struct pie_sched_data *q = qdisc_priv(sch);
  95         u64 rnd;
  96         u64 local_prob = q->vars.prob;
  97         u32 mtu = psched_mtu(qdisc_dev(sch));
  98 
  99         /* If there is still burst allowance left skip random early drop */
 100         if (q->vars.burst_time > 0)
 101                 return false;
 102 
 103         /* If current delay is less than half of target, and
 104          * if drop prob is low already, disable early_drop
 105          */
 106         if ((q->vars.qdelay < q->params.target / 2) &&
 107             (q->vars.prob < MAX_PROB / 5))
 108                 return false;
 109 
 110         /* If we have fewer than 2 mtu-sized packets, disable drop_early,
 111          * similar to min_th in RED
 112          */
 113         if (sch->qstats.backlog < 2 * mtu)
 114                 return false;
 115 
 116         /* If bytemode is turned on, use packet size to compute new
 117          * probablity. Smaller packets will have lower drop prob in this case
 118          */
 119         if (q->params.bytemode && packet_size <= mtu)
 120                 local_prob = (u64)packet_size * div_u64(local_prob, mtu);
 121         else
 122                 local_prob = q->vars.prob;
 123 
 124         if (local_prob == 0) {
 125                 q->vars.accu_prob = 0;
 126                 q->vars.accu_prob_overflows = 0;
 127         }
 128 
 129         if (local_prob > MAX_PROB - q->vars.accu_prob)
 130                 q->vars.accu_prob_overflows++;
 131 
 132         q->vars.accu_prob += local_prob;
 133 
 134         if (q->vars.accu_prob_overflows == 0 &&
 135             q->vars.accu_prob < (MAX_PROB / 100) * 85)
 136                 return false;
 137         if (q->vars.accu_prob_overflows == 8 &&
 138             q->vars.accu_prob >= MAX_PROB / 2)
 139                 return true;
 140 
 141         prandom_bytes(&rnd, 8);
 142         if (rnd < local_prob) {
 143                 q->vars.accu_prob = 0;
 144                 q->vars.accu_prob_overflows = 0;
 145                 return true;
 146         }
 147 
 148         return false;
 149 }
 150 
 151 static int pie_qdisc_enqueue(struct sk_buff *skb, struct Qdisc *sch,
 152                              struct sk_buff **to_free)
 153 {
 154         struct pie_sched_data *q = qdisc_priv(sch);
 155         bool enqueue = false;
 156 
 157         if (unlikely(qdisc_qlen(sch) >= sch->limit)) {
 158                 q->stats.overlimit++;
 159                 goto out;
 160         }
 161 
 162         if (!drop_early(sch, skb->len)) {
 163                 enqueue = true;
 164         } else if (q->params.ecn && (q->vars.prob <= MAX_PROB / 10) &&
 165                    INET_ECN_set_ce(skb)) {
 166                 /* If packet is ecn capable, mark it if drop probability
 167                  * is lower than 10%, else drop it.
 168                  */
 169                 q->stats.ecn_mark++;
 170                 enqueue = true;
 171         }
 172 
 173         /* we can enqueue the packet */
 174         if (enqueue) {
 175                 q->stats.packets_in++;
 176                 if (qdisc_qlen(sch) > q->stats.maxq)
 177                         q->stats.maxq = qdisc_qlen(sch);
 178 
 179                 return qdisc_enqueue_tail(skb, sch);
 180         }
 181 
 182 out:
 183         q->stats.dropped++;
 184         q->vars.accu_prob = 0;
 185         q->vars.accu_prob_overflows = 0;
 186         return qdisc_drop(skb, sch, to_free);
 187 }
 188 
 189 static const struct nla_policy pie_policy[TCA_PIE_MAX + 1] = {
 190         [TCA_PIE_TARGET] = {.type = NLA_U32},
 191         [TCA_PIE_LIMIT] = {.type = NLA_U32},
 192         [TCA_PIE_TUPDATE] = {.type = NLA_U32},
 193         [TCA_PIE_ALPHA] = {.type = NLA_U32},
 194         [TCA_PIE_BETA] = {.type = NLA_U32},
 195         [TCA_PIE_ECN] = {.type = NLA_U32},
 196         [TCA_PIE_BYTEMODE] = {.type = NLA_U32},
 197 };
 198 
 199 static int pie_change(struct Qdisc *sch, struct nlattr *opt,
 200                       struct netlink_ext_ack *extack)
 201 {
 202         struct pie_sched_data *q = qdisc_priv(sch);
 203         struct nlattr *tb[TCA_PIE_MAX + 1];
 204         unsigned int qlen, dropped = 0;
 205         int err;
 206 
 207         if (!opt)
 208                 return -EINVAL;
 209 
 210         err = nla_parse_nested_deprecated(tb, TCA_PIE_MAX, opt, pie_policy,
 211                                           NULL);
 212         if (err < 0)
 213                 return err;
 214 
 215         sch_tree_lock(sch);
 216 
 217         /* convert from microseconds to pschedtime */
 218         if (tb[TCA_PIE_TARGET]) {
 219                 /* target is in us */
 220                 u32 target = nla_get_u32(tb[TCA_PIE_TARGET]);
 221 
 222                 /* convert to pschedtime */
 223                 q->params.target = PSCHED_NS2TICKS((u64)target * NSEC_PER_USEC);
 224         }
 225 
 226         /* tupdate is in jiffies */
 227         if (tb[TCA_PIE_TUPDATE])
 228                 q->params.tupdate =
 229                         usecs_to_jiffies(nla_get_u32(tb[TCA_PIE_TUPDATE]));
 230 
 231         if (tb[TCA_PIE_LIMIT]) {
 232                 u32 limit = nla_get_u32(tb[TCA_PIE_LIMIT]);
 233 
 234                 q->params.limit = limit;
 235                 sch->limit = limit;
 236         }
 237 
 238         if (tb[TCA_PIE_ALPHA])
 239                 q->params.alpha = nla_get_u32(tb[TCA_PIE_ALPHA]);
 240 
 241         if (tb[TCA_PIE_BETA])
 242                 q->params.beta = nla_get_u32(tb[TCA_PIE_BETA]);
 243 
 244         if (tb[TCA_PIE_ECN])
 245                 q->params.ecn = nla_get_u32(tb[TCA_PIE_ECN]);
 246 
 247         if (tb[TCA_PIE_BYTEMODE])
 248                 q->params.bytemode = nla_get_u32(tb[TCA_PIE_BYTEMODE]);
 249 
 250         /* Drop excess packets if new limit is lower */
 251         qlen = sch->q.qlen;
 252         while (sch->q.qlen > sch->limit) {
 253                 struct sk_buff *skb = __qdisc_dequeue_head(&sch->q);
 254 
 255                 dropped += qdisc_pkt_len(skb);
 256                 qdisc_qstats_backlog_dec(sch, skb);
 257                 rtnl_qdisc_drop(skb, sch);
 258         }
 259         qdisc_tree_reduce_backlog(sch, qlen - sch->q.qlen, dropped);
 260 
 261         sch_tree_unlock(sch);
 262         return 0;
 263 }
 264 
 265 static void pie_process_dequeue(struct Qdisc *sch, struct sk_buff *skb)
 266 {
 267         struct pie_sched_data *q = qdisc_priv(sch);
 268         int qlen = sch->qstats.backlog; /* current queue size in bytes */
 269 
 270         /* If current queue is about 10 packets or more and dq_count is unset
 271          * we have enough packets to calculate the drain rate. Save
 272          * current time as dq_tstamp and start measurement cycle.
 273          */
 274         if (qlen >= QUEUE_THRESHOLD && q->vars.dq_count == DQCOUNT_INVALID) {
 275                 q->vars.dq_tstamp = psched_get_time();
 276                 q->vars.dq_count = 0;
 277         }
 278 
 279         /* Calculate the average drain rate from this value.  If queue length
 280          * has receded to a small value viz., <= QUEUE_THRESHOLD bytes,reset
 281          * the dq_count to -1 as we don't have enough packets to calculate the
 282          * drain rate anymore The following if block is entered only when we
 283          * have a substantial queue built up (QUEUE_THRESHOLD bytes or more)
 284          * and we calculate the drain rate for the threshold here.  dq_count is
 285          * in bytes, time difference in psched_time, hence rate is in
 286          * bytes/psched_time.
 287          */
 288         if (q->vars.dq_count != DQCOUNT_INVALID) {
 289                 q->vars.dq_count += skb->len;
 290 
 291                 if (q->vars.dq_count >= QUEUE_THRESHOLD) {
 292                         psched_time_t now = psched_get_time();
 293                         u32 dtime = now - q->vars.dq_tstamp;
 294                         u32 count = q->vars.dq_count << PIE_SCALE;
 295 
 296                         if (dtime == 0)
 297                                 return;
 298 
 299                         count = count / dtime;
 300 
 301                         if (q->vars.avg_dq_rate == 0)
 302                                 q->vars.avg_dq_rate = count;
 303                         else
 304                                 q->vars.avg_dq_rate =
 305                                     (q->vars.avg_dq_rate -
 306                                      (q->vars.avg_dq_rate >> 3)) + (count >> 3);
 307 
 308                         /* If the queue has receded below the threshold, we hold
 309                          * on to the last drain rate calculated, else we reset
 310                          * dq_count to 0 to re-enter the if block when the next
 311                          * packet is dequeued
 312                          */
 313                         if (qlen < QUEUE_THRESHOLD) {
 314                                 q->vars.dq_count = DQCOUNT_INVALID;
 315                         } else {
 316                                 q->vars.dq_count = 0;
 317                                 q->vars.dq_tstamp = psched_get_time();
 318                         }
 319 
 320                         if (q->vars.burst_time > 0) {
 321                                 if (q->vars.burst_time > dtime)
 322                                         q->vars.burst_time -= dtime;
 323                                 else
 324                                         q->vars.burst_time = 0;
 325                         }
 326                 }
 327         }
 328 }
 329 
 330 static void calculate_probability(struct Qdisc *sch)
 331 {
 332         struct pie_sched_data *q = qdisc_priv(sch);
 333         u32 qlen = sch->qstats.backlog; /* queue size in bytes */
 334         psched_time_t qdelay = 0;       /* in pschedtime */
 335         psched_time_t qdelay_old = q->vars.qdelay;      /* in pschedtime */
 336         s64 delta = 0;          /* determines the change in probability */
 337         u64 oldprob;
 338         u64 alpha, beta;
 339         u32 power;
 340         bool update_prob = true;
 341 
 342         q->vars.qdelay_old = q->vars.qdelay;
 343 
 344         if (q->vars.avg_dq_rate > 0)
 345                 qdelay = (qlen << PIE_SCALE) / q->vars.avg_dq_rate;
 346         else
 347                 qdelay = 0;
 348 
 349         /* If qdelay is zero and qlen is not, it means qlen is very small, less
 350          * than dequeue_rate, so we do not update probabilty in this round
 351          */
 352         if (qdelay == 0 && qlen != 0)
 353                 update_prob = false;
 354 
 355         /* In the algorithm, alpha and beta are between 0 and 2 with typical
 356          * value for alpha as 0.125. In this implementation, we use values 0-32
 357          * passed from user space to represent this. Also, alpha and beta have
 358          * unit of HZ and need to be scaled before they can used to update
 359          * probability. alpha/beta are updated locally below by scaling down
 360          * by 16 to come to 0-2 range.
 361          */
 362         alpha = ((u64)q->params.alpha * (MAX_PROB / PSCHED_TICKS_PER_SEC)) >> 4;
 363         beta = ((u64)q->params.beta * (MAX_PROB / PSCHED_TICKS_PER_SEC)) >> 4;
 364 
 365         /* We scale alpha and beta differently depending on how heavy the
 366          * congestion is. Please see RFC 8033 for details.
 367          */
 368         if (q->vars.prob < MAX_PROB / 10) {
 369                 alpha >>= 1;
 370                 beta >>= 1;
 371 
 372                 power = 100;
 373                 while (q->vars.prob < div_u64(MAX_PROB, power) &&
 374                        power <= 1000000) {
 375                         alpha >>= 2;
 376                         beta >>= 2;
 377                         power *= 10;
 378                 }
 379         }
 380 
 381         /* alpha and beta should be between 0 and 32, in multiples of 1/16 */
 382         delta += alpha * (u64)(qdelay - q->params.target);
 383         delta += beta * (u64)(qdelay - qdelay_old);
 384 
 385         oldprob = q->vars.prob;
 386 
 387         /* to ensure we increase probability in steps of no more than 2% */
 388         if (delta > (s64)(MAX_PROB / (100 / 2)) &&
 389             q->vars.prob >= MAX_PROB / 10)
 390                 delta = (MAX_PROB / 100) * 2;
 391 
 392         /* Non-linear drop:
 393          * Tune drop probability to increase quickly for high delays(>= 250ms)
 394          * 250ms is derived through experiments and provides error protection
 395          */
 396 
 397         if (qdelay > (PSCHED_NS2TICKS(250 * NSEC_PER_MSEC)))
 398                 delta += MAX_PROB / (100 / 2);
 399 
 400         q->vars.prob += delta;
 401 
 402         if (delta > 0) {
 403                 /* prevent overflow */
 404                 if (q->vars.prob < oldprob) {
 405                         q->vars.prob = MAX_PROB;
 406                         /* Prevent normalization error. If probability is at
 407                          * maximum value already, we normalize it here, and
 408                          * skip the check to do a non-linear drop in the next
 409                          * section.
 410                          */
 411                         update_prob = false;
 412                 }
 413         } else {
 414                 /* prevent underflow */
 415                 if (q->vars.prob > oldprob)
 416                         q->vars.prob = 0;
 417         }
 418 
 419         /* Non-linear drop in probability: Reduce drop probability quickly if
 420          * delay is 0 for 2 consecutive Tupdate periods.
 421          */
 422 
 423         if (qdelay == 0 && qdelay_old == 0 && update_prob)
 424                 /* Reduce drop probability to 98.4% */
 425                 q->vars.prob -= q->vars.prob / 64u;
 426 
 427         q->vars.qdelay = qdelay;
 428         q->vars.qlen_old = qlen;
 429 
 430         /* We restart the measurement cycle if the following conditions are met
 431          * 1. If the delay has been low for 2 consecutive Tupdate periods
 432          * 2. Calculated drop probability is zero
 433          * 3. We have atleast one estimate for the avg_dq_rate ie.,
 434          *    is a non-zero value
 435          */
 436         if ((q->vars.qdelay < q->params.target / 2) &&
 437             (q->vars.qdelay_old < q->params.target / 2) &&
 438             q->vars.prob == 0 &&
 439             q->vars.avg_dq_rate > 0)
 440                 pie_vars_init(&q->vars);
 441 }
 442 
 443 static void pie_timer(struct timer_list *t)
 444 {
 445         struct pie_sched_data *q = from_timer(q, t, adapt_timer);
 446         struct Qdisc *sch = q->sch;
 447         spinlock_t *root_lock = qdisc_lock(qdisc_root_sleeping(sch));
 448 
 449         spin_lock(root_lock);
 450         calculate_probability(sch);
 451 
 452         /* reset the timer to fire after 'tupdate'. tupdate is in jiffies. */
 453         if (q->params.tupdate)
 454                 mod_timer(&q->adapt_timer, jiffies + q->params.tupdate);
 455         spin_unlock(root_lock);
 456 }
 457 
 458 static int pie_init(struct Qdisc *sch, struct nlattr *opt,
 459                     struct netlink_ext_ack *extack)
 460 {
 461         struct pie_sched_data *q = qdisc_priv(sch);
 462 
 463         pie_params_init(&q->params);
 464         pie_vars_init(&q->vars);
 465         sch->limit = q->params.limit;
 466 
 467         q->sch = sch;
 468         timer_setup(&q->adapt_timer, pie_timer, 0);
 469 
 470         if (opt) {
 471                 int err = pie_change(sch, opt, extack);
 472 
 473                 if (err)
 474                         return err;
 475         }
 476 
 477         mod_timer(&q->adapt_timer, jiffies + HZ / 2);
 478         return 0;
 479 }
 480 
 481 static int pie_dump(struct Qdisc *sch, struct sk_buff *skb)
 482 {
 483         struct pie_sched_data *q = qdisc_priv(sch);
 484         struct nlattr *opts;
 485 
 486         opts = nla_nest_start_noflag(skb, TCA_OPTIONS);
 487         if (!opts)
 488                 goto nla_put_failure;
 489 
 490         /* convert target from pschedtime to us */
 491         if (nla_put_u32(skb, TCA_PIE_TARGET,
 492                         ((u32)PSCHED_TICKS2NS(q->params.target)) /
 493                         NSEC_PER_USEC) ||
 494             nla_put_u32(skb, TCA_PIE_LIMIT, sch->limit) ||
 495             nla_put_u32(skb, TCA_PIE_TUPDATE,
 496                         jiffies_to_usecs(q->params.tupdate)) ||
 497             nla_put_u32(skb, TCA_PIE_ALPHA, q->params.alpha) ||
 498             nla_put_u32(skb, TCA_PIE_BETA, q->params.beta) ||
 499             nla_put_u32(skb, TCA_PIE_ECN, q->params.ecn) ||
 500             nla_put_u32(skb, TCA_PIE_BYTEMODE, q->params.bytemode))
 501                 goto nla_put_failure;
 502 
 503         return nla_nest_end(skb, opts);
 504 
 505 nla_put_failure:
 506         nla_nest_cancel(skb, opts);
 507         return -1;
 508 }
 509 
 510 static int pie_dump_stats(struct Qdisc *sch, struct gnet_dump *d)
 511 {
 512         struct pie_sched_data *q = qdisc_priv(sch);
 513         struct tc_pie_xstats st = {
 514                 .prob           = q->vars.prob,
 515                 .delay          = ((u32)PSCHED_TICKS2NS(q->vars.qdelay)) /
 516                                    NSEC_PER_USEC,
 517                 /* unscale and return dq_rate in bytes per sec */
 518                 .avg_dq_rate    = q->vars.avg_dq_rate *
 519                                   (PSCHED_TICKS_PER_SEC) >> PIE_SCALE,
 520                 .packets_in     = q->stats.packets_in,
 521                 .overlimit      = q->stats.overlimit,
 522                 .maxq           = q->stats.maxq,
 523                 .dropped        = q->stats.dropped,
 524                 .ecn_mark       = q->stats.ecn_mark,
 525         };
 526 
 527         return gnet_stats_copy_app(d, &st, sizeof(st));
 528 }
 529 
 530 static struct sk_buff *pie_qdisc_dequeue(struct Qdisc *sch)
 531 {
 532         struct sk_buff *skb = qdisc_dequeue_head(sch);
 533 
 534         if (!skb)
 535                 return NULL;
 536 
 537         pie_process_dequeue(sch, skb);
 538         return skb;
 539 }
 540 
 541 static void pie_reset(struct Qdisc *sch)
 542 {
 543         struct pie_sched_data *q = qdisc_priv(sch);
 544 
 545         qdisc_reset_queue(sch);
 546         pie_vars_init(&q->vars);
 547 }
 548 
 549 static void pie_destroy(struct Qdisc *sch)
 550 {
 551         struct pie_sched_data *q = qdisc_priv(sch);
 552 
 553         q->params.tupdate = 0;
 554         del_timer_sync(&q->adapt_timer);
 555 }
 556 
 557 static struct Qdisc_ops pie_qdisc_ops __read_mostly = {
 558         .id = "pie",
 559         .priv_size      = sizeof(struct pie_sched_data),
 560         .enqueue        = pie_qdisc_enqueue,
 561         .dequeue        = pie_qdisc_dequeue,
 562         .peek           = qdisc_peek_dequeued,
 563         .init           = pie_init,
 564         .destroy        = pie_destroy,
 565         .reset          = pie_reset,
 566         .change         = pie_change,
 567         .dump           = pie_dump,
 568         .dump_stats     = pie_dump_stats,
 569         .owner          = THIS_MODULE,
 570 };
 571 
 572 static int __init pie_module_init(void)
 573 {
 574         return register_qdisc(&pie_qdisc_ops);
 575 }
 576 
 577 static void __exit pie_module_exit(void)
 578 {
 579         unregister_qdisc(&pie_qdisc_ops);
 580 }
 581 
 582 module_init(pie_module_init);
 583 module_exit(pie_module_exit);
 584 
 585 MODULE_DESCRIPTION("Proportional Integral controller Enhanced (PIE) scheduler");
 586 MODULE_AUTHOR("Vijay Subramanian");
 587 MODULE_AUTHOR("Mythili Prabhu");
 588 MODULE_LICENSE("GPL");
/* [<][>][^][v][top][bottom][index][help] */
root/net/sched/sch_pie.c

DEFINITIONS
