1 // SPDX-License-Identifier: GPL-2.0-only
2 /* net/sched/sch_hhf.c Heavy-Hitter Filter (HHF)
3 *
4 * Copyright (C) 2013 Terry Lam <vtlam@google.com>
5 * Copyright (C) 2013 Nandita Dukkipati <nanditad@google.com>
6 */
7
8 #include <linux/jiffies.h>
9 #include <linux/module.h>
10 #include <linux/skbuff.h>
11 #include <linux/vmalloc.h>
12 #include <linux/siphash.h>
13 #include <net/pkt_sched.h>
14 #include <net/sock.h>
15
16 /* Heavy-Hitter Filter (HHF)
17 *
18 * Principles :
19 * Flows are classified into two buckets: non-heavy-hitter and heavy-hitter
20 * buckets. Initially, a new flow starts as non-heavy-hitter. Once classified
21 * as heavy-hitter, it is immediately switched to the heavy-hitter bucket.
22 * The buckets are dequeued by a Weighted Deficit Round Robin (WDRR) scheduler,
23 * in which the heavy-hitter bucket is served with less weight.
24 * In other words, non-heavy-hitters (e.g., short bursts of critical traffic)
25 * are isolated from heavy-hitters (e.g., persistent bulk traffic) and also have
26 * higher share of bandwidth.
27 *
28 * To capture heavy-hitters, we use the "multi-stage filter" algorithm in the
29 * following paper:
30 * [EV02] C. Estan and G. Varghese, "New Directions in Traffic Measurement and
31 * Accounting", in ACM SIGCOMM, 2002.
32 *
33 * Conceptually, a multi-stage filter comprises k independent hash functions
34 * and k counter arrays. Packets are indexed into k counter arrays by k hash
35 * functions, respectively. The counters are then increased by the packet sizes.
36 * Therefore,
37 * - For a heavy-hitter flow: *all* of its k array counters must be large.
38 * - For a non-heavy-hitter flow: some of its k array counters can be large
39 * due to hash collision with other small flows; however, with high
40 * probability, not *all* k counters are large.
41 *
42 * By the design of the multi-stage filter algorithm, the false negative rate
43 * (heavy-hitters getting away uncaptured) is zero. However, the algorithm is
44 * susceptible to false positives (non-heavy-hitters mistakenly classified as
45 * heavy-hitters).
46 * Therefore, we also implement the following optimizations to reduce false
47 * positives by avoiding unnecessary increment of the counter values:
48 * - Optimization O1: once a heavy-hitter is identified, its bytes are not
49 * accounted in the array counters. This technique is called "shielding"
50 * in Section 3.3.1 of [EV02].
51 * - Optimization O2: conservative update of counters
52 * (Section 3.3.2 of [EV02]),
53 * New counter value = max {old counter value,
54 * smallest counter value + packet bytes}
55 *
56 * Finally, we refresh the counters periodically since otherwise the counter
57 * values will keep accumulating.
58 *
59 * Once a flow is classified as heavy-hitter, we also save its per-flow state
60 * in an exact-matching flow table so that its subsequent packets can be
61 * dispatched to the heavy-hitter bucket accordingly.
62 *
63 *
64 * At a high level, this qdisc works as follows:
65 * Given a packet p:
66 * - If the flow-id of p (e.g., TCP 5-tuple) is already in the exact-matching
67 * heavy-hitter flow table, denoted table T, then send p to the heavy-hitter
68 * bucket.
69 * - Otherwise, forward p to the multi-stage filter, denoted filter F
70 * + If F decides that p belongs to a non-heavy-hitter flow, then send p
71 * to the non-heavy-hitter bucket.
72 * + Otherwise, if F decides that p belongs to a new heavy-hitter flow,
73 * then set up a new flow entry for the flow-id of p in the table T and
74 * send p to the heavy-hitter bucket.
75 *
76 * In this implementation:
77 * - T is a fixed-size hash-table with 1024 entries. Hash collision is
78 * resolved by linked-list chaining.
79 * - F has four counter arrays, each array containing 1024 32-bit counters.
80 * That means 4 * 1024 * 32 bits = 16KB of memory.
81 * - Since each array in F contains 1024 counters, 10 bits are sufficient to
82 * index into each array.
83 * Hence, instead of having four hash functions, we chop the 32-bit
84 * skb-hash into three 10-bit chunks, and the remaining 10-bit chunk is
85 * computed as XOR sum of those three chunks.
86 * - We need to clear the counter arrays periodically; however, directly
87 * memsetting 16KB of memory can lead to cache eviction and unwanted delay.
88 * So by representing each counter by a valid bit, we only need to reset
89 * 4K of 1 bit (i.e. 512 bytes) instead of 16KB of memory.
90 * - The Deficit Round Robin engine is taken from fq_codel implementation
91 * (net/sched/sch_fq_codel.c). Note that wdrr_bucket corresponds to
92 * fq_codel_flow in fq_codel implementation.
93 *
94 */
95
96 /* Non-configurable parameters */
97 #define HH_FLOWS_CNT 1024 /* number of entries in exact-matching table T */
98 #define HHF_ARRAYS_CNT 4 /* number of arrays in multi-stage filter F */
99 #define HHF_ARRAYS_LEN 1024 /* number of counters in each array of F */
100 #define HHF_BIT_MASK_LEN 10 /* masking 10 bits */
101 #define HHF_BIT_MASK 0x3FF /* bitmask of 10 bits */
102
103 #define WDRR_BUCKET_CNT 2 /* two buckets for Weighted DRR */
104 enum wdrr_bucket_idx {
105 WDRR_BUCKET_FOR_HH = 0, /* bucket id for heavy-hitters */
106 WDRR_BUCKET_FOR_NON_HH = 1 /* bucket id for non-heavy-hitters */
107 };
108
109 #define hhf_time_before(a, b) \
110 (typecheck(u32, a) && typecheck(u32, b) && ((s32)((a) - (b)) < 0))
111
112 /* Heavy-hitter per-flow state */
113 struct hh_flow_state {
114 u32 hash_id; /* hash of flow-id (e.g. TCP 5-tuple) */
115 u32 hit_timestamp; /* last time heavy-hitter was seen */
116 struct list_head flowchain; /* chaining under hash collision */
117 };
118
119 /* Weighted Deficit Round Robin (WDRR) scheduler */
120 struct wdrr_bucket {
121 struct sk_buff *head;
122 struct sk_buff *tail;
123 struct list_head bucketchain;
124 int deficit;
125 };
126
127 struct hhf_sched_data {
128 struct wdrr_bucket buckets[WDRR_BUCKET_CNT];
129 siphash_key_t perturbation; /* hash perturbation */
130 u32 quantum; /* psched_mtu(qdisc_dev(sch)); */
131 u32 drop_overlimit; /* number of times max qdisc packet
132 * limit was hit
133 */
134 struct list_head *hh_flows; /* table T (currently active HHs) */
135 u32 hh_flows_limit; /* max active HH allocs */
136 u32 hh_flows_overlimit; /* num of disallowed HH allocs */
137 u32 hh_flows_total_cnt; /* total admitted HHs */
138 u32 hh_flows_current_cnt; /* total current HHs */
139 u32 *hhf_arrays[HHF_ARRAYS_CNT]; /* HH filter F */
140 u32 hhf_arrays_reset_timestamp; /* last time hhf_arrays
141 * was reset
142 */
143 unsigned long *hhf_valid_bits[HHF_ARRAYS_CNT]; /* shadow valid bits
144 * of hhf_arrays
145 */
146 /* Similar to the "new_flows" vs. "old_flows" concept in fq_codel DRR */
147 struct list_head new_buckets; /* list of new buckets */
148 struct list_head old_buckets; /* list of old buckets */
149
150 /* Configurable HHF parameters */
151 u32 hhf_reset_timeout; /* interval to reset counter
152 * arrays in filter F
153 * (default 40ms)
154 */
155 u32 hhf_admit_bytes; /* counter thresh to classify as
156 * HH (default 128KB).
157 * With these default values,
158 * 128KB / 40ms = 25 Mbps
159 * i.e., we expect to capture HHs
160 * sending > 25 Mbps.
161 */
162 u32 hhf_evict_timeout; /* aging threshold to evict idle
163 * HHs out of table T. This should
164 * be large enough to avoid
165 * reordering during HH eviction.
166 * (default 1s)
167 */
168 u32 hhf_non_hh_weight; /* WDRR weight for non-HHs
169 * (default 2,
170 * i.e., non-HH : HH = 2 : 1)
171 */
172 };
173
174 static u32 hhf_time_stamp(void)
175 {
176 return jiffies;
177 }
178
179 /* Looks up a heavy-hitter flow in a chaining list of table T. */
180 static struct hh_flow_state *seek_list(const u32 hash,
181 struct list_head *head,
182 struct hhf_sched_data *q)
183 {
184 struct hh_flow_state *flow, *next;
185 u32 now = hhf_time_stamp();
186
187 if (list_empty(head))
188 return NULL;
189
190 list_for_each_entry_safe(flow, next, head, flowchain) {
191 u32 prev = flow->hit_timestamp + q->hhf_evict_timeout;
192
193 if (hhf_time_before(prev, now)) {
194 /* Delete expired heavy-hitters, but preserve one entry
195 * to avoid kzalloc() when next time this slot is hit.
196 */
197 if (list_is_last(&flow->flowchain, head))
198 return NULL;
199 list_del(&flow->flowchain);
200 kfree(flow);
201 q->hh_flows_current_cnt--;
202 } else if (flow->hash_id == hash) {
203 return flow;
204 }
205 }
206 return NULL;
207 }
208
209 /* Returns a flow state entry for a new heavy-hitter. Either reuses an expired
210 * entry or dynamically alloc a new entry.
211 */
212 static struct hh_flow_state *alloc_new_hh(struct list_head *head,
213 struct hhf_sched_data *q)
214 {
215 struct hh_flow_state *flow;
216 u32 now = hhf_time_stamp();
217
218 if (!list_empty(head)) {
219 /* Find an expired heavy-hitter flow entry. */
220 list_for_each_entry(flow, head, flowchain) {
221 u32 prev = flow->hit_timestamp + q->hhf_evict_timeout;
222
223 if (hhf_time_before(prev, now))
224 return flow;
225 }
226 }
227
228 if (q->hh_flows_current_cnt >= q->hh_flows_limit) {
229 q->hh_flows_overlimit++;
230 return NULL;
231 }
232 /* Create new entry. */
233 flow = kzalloc(sizeof(struct hh_flow_state), GFP_ATOMIC);
234 if (!flow)
235 return NULL;
236
237 q->hh_flows_current_cnt++;
238 INIT_LIST_HEAD(&flow->flowchain);
239 list_add_tail(&flow->flowchain, head);
240
241 return flow;
242 }
243
244 /* Assigns packets to WDRR buckets. Implements a multi-stage filter to
245 * classify heavy-hitters.
246 */
247 static enum wdrr_bucket_idx hhf_classify(struct sk_buff *skb, struct Qdisc *sch)
248 {
249 struct hhf_sched_data *q = qdisc_priv(sch);
250 u32 tmp_hash, hash;
251 u32 xorsum, filter_pos[HHF_ARRAYS_CNT], flow_pos;
252 struct hh_flow_state *flow;
253 u32 pkt_len, min_hhf_val;
254 int i;
255 u32 prev;
256 u32 now = hhf_time_stamp();
257
258 /* Reset the HHF counter arrays if this is the right time. */
259 prev = q->hhf_arrays_reset_timestamp + q->hhf_reset_timeout;
260 if (hhf_time_before(prev, now)) {
261 for (i = 0; i < HHF_ARRAYS_CNT; i++)
262 bitmap_zero(q->hhf_valid_bits[i], HHF_ARRAYS_LEN);
263 q->hhf_arrays_reset_timestamp = now;
264 }
265
266 /* Get hashed flow-id of the skb. */
267 hash = skb_get_hash_perturb(skb, &q->perturbation);
268
269 /* Check if this packet belongs to an already established HH flow. */
270 flow_pos = hash & HHF_BIT_MASK;
271 flow = seek_list(hash, &q->hh_flows[flow_pos], q);
272 if (flow) { /* found its HH flow */
273 flow->hit_timestamp = now;
274 return WDRR_BUCKET_FOR_HH;
275 }
276
277 /* Now pass the packet through the multi-stage filter. */
278 tmp_hash = hash;
279 xorsum = 0;
280 for (i = 0; i < HHF_ARRAYS_CNT - 1; i++) {
281 /* Split the skb_hash into three 10-bit chunks. */
282 filter_pos[i] = tmp_hash & HHF_BIT_MASK;
283 xorsum ^= filter_pos[i];
284 tmp_hash >>= HHF_BIT_MASK_LEN;
285 }
286 /* The last chunk is computed as XOR sum of other chunks. */
287 filter_pos[HHF_ARRAYS_CNT - 1] = xorsum ^ tmp_hash;
288
289 pkt_len = qdisc_pkt_len(skb);
290 min_hhf_val = ~0U;
291 for (i = 0; i < HHF_ARRAYS_CNT; i++) {
292 u32 val;
293
294 if (!test_bit(filter_pos[i], q->hhf_valid_bits[i])) {
295 q->hhf_arrays[i][filter_pos[i]] = 0;
296 __set_bit(filter_pos[i], q->hhf_valid_bits[i]);
297 }
298
299 val = q->hhf_arrays[i][filter_pos[i]] + pkt_len;
300 if (min_hhf_val > val)
301 min_hhf_val = val;
302 }
303
304 /* Found a new HH iff all counter values > HH admit threshold. */
305 if (min_hhf_val > q->hhf_admit_bytes) {
306 /* Just captured a new heavy-hitter. */
307 flow = alloc_new_hh(&q->hh_flows[flow_pos], q);
308 if (!flow) /* memory alloc problem */
309 return WDRR_BUCKET_FOR_NON_HH;
310 flow->hash_id = hash;
311 flow->hit_timestamp = now;
312 q->hh_flows_total_cnt++;
313
314 /* By returning without updating counters in q->hhf_arrays,
315 * we implicitly implement "shielding" (see Optimization O1).
316 */
317 return WDRR_BUCKET_FOR_HH;
318 }
319
320 /* Conservative update of HHF arrays (see Optimization O2). */
321 for (i = 0; i < HHF_ARRAYS_CNT; i++) {
322 if (q->hhf_arrays[i][filter_pos[i]] < min_hhf_val)
323 q->hhf_arrays[i][filter_pos[i]] = min_hhf_val;
324 }
325 return WDRR_BUCKET_FOR_NON_HH;
326 }
327
328 /* Removes one skb from head of bucket. */
329 static struct sk_buff *dequeue_head(struct wdrr_bucket *bucket)
330 {
331 struct sk_buff *skb = bucket->head;
332
333 bucket->head = skb->next;
334 skb_mark_not_on_list(skb);
335 return skb;
336 }
337
338 /* Tail-adds skb to bucket. */
339 static void bucket_add(struct wdrr_bucket *bucket, struct sk_buff *skb)
340 {
341 if (bucket->head == NULL)
342 bucket->head = skb;
343 else
344 bucket->tail->next = skb;
345 bucket->tail = skb;
346 skb->next = NULL;
347 }
348
349 static unsigned int hhf_drop(struct Qdisc *sch, struct sk_buff **to_free)
350 {
351 struct hhf_sched_data *q = qdisc_priv(sch);
352 struct wdrr_bucket *bucket;
353
354 /* Always try to drop from heavy-hitters first. */
355 bucket = &q->buckets[WDRR_BUCKET_FOR_HH];
356 if (!bucket->head)
357 bucket = &q->buckets[WDRR_BUCKET_FOR_NON_HH];
358
359 if (bucket->head) {
360 struct sk_buff *skb = dequeue_head(bucket);
361
362 sch->q.qlen--;
363 qdisc_qstats_backlog_dec(sch, skb);
364 qdisc_drop(skb, sch, to_free);
365 }
366
367 /* Return id of the bucket from which the packet was dropped. */
368 return bucket - q->buckets;
369 }
370
371 static int hhf_enqueue(struct sk_buff *skb, struct Qdisc *sch,
372 struct sk_buff **to_free)
373 {
374 struct hhf_sched_data *q = qdisc_priv(sch);
375 enum wdrr_bucket_idx idx;
376 struct wdrr_bucket *bucket;
377 unsigned int prev_backlog;
378
379 idx = hhf_classify(skb, sch);
380
381 bucket = &q->buckets[idx];
382 bucket_add(bucket, skb);
383 qdisc_qstats_backlog_inc(sch, skb);
384
385 if (list_empty(&bucket->bucketchain)) {
386 unsigned int weight;
387
388 /* The logic of new_buckets vs. old_buckets is the same as
389 * new_flows vs. old_flows in the implementation of fq_codel,
390 * i.e., short bursts of non-HHs should have strict priority.
391 */
392 if (idx == WDRR_BUCKET_FOR_HH) {
393 /* Always move heavy-hitters to old bucket. */
394 weight = 1;
395 list_add_tail(&bucket->bucketchain, &q->old_buckets);
396 } else {
397 weight = q->hhf_non_hh_weight;
398 list_add_tail(&bucket->bucketchain, &q->new_buckets);
399 }
400 bucket->deficit = weight * q->quantum;
401 }
402 if (++sch->q.qlen <= sch->limit)
403 return NET_XMIT_SUCCESS;
404
405 prev_backlog = sch->qstats.backlog;
406 q->drop_overlimit++;
407 /* Return Congestion Notification only if we dropped a packet from this
408 * bucket.
409 */
410 if (hhf_drop(sch, to_free) == idx)
411 return NET_XMIT_CN;
412
413 /* As we dropped a packet, better let upper stack know this. */
414 qdisc_tree_reduce_backlog(sch, 1, prev_backlog - sch->qstats.backlog);
415 return NET_XMIT_SUCCESS;
416 }
417
418 static struct sk_buff *hhf_dequeue(struct Qdisc *sch)
419 {
420 struct hhf_sched_data *q = qdisc_priv(sch);
421 struct sk_buff *skb = NULL;
422 struct wdrr_bucket *bucket;
423 struct list_head *head;
424
425 begin:
426 head = &q->new_buckets;
427 if (list_empty(head)) {
428 head = &q->old_buckets;
429 if (list_empty(head))
430 return NULL;
431 }
432 bucket = list_first_entry(head, struct wdrr_bucket, bucketchain);
433
434 if (bucket->deficit <= 0) {
435 int weight = (bucket - q->buckets == WDRR_BUCKET_FOR_HH) ?
436 1 : q->hhf_non_hh_weight;
437
438 bucket->deficit += weight * q->quantum;
439 list_move_tail(&bucket->bucketchain, &q->old_buckets);
440 goto begin;
441 }
442
443 if (bucket->head) {
444 skb = dequeue_head(bucket);
445 sch->q.qlen--;
446 qdisc_qstats_backlog_dec(sch, skb);
447 }
448
449 if (!skb) {
450 /* Force a pass through old_buckets to prevent starvation. */
451 if ((head == &q->new_buckets) && !list_empty(&q->old_buckets))
452 list_move_tail(&bucket->bucketchain, &q->old_buckets);
453 else
454 list_del_init(&bucket->bucketchain);
455 goto begin;
456 }
457 qdisc_bstats_update(sch, skb);
458 bucket->deficit -= qdisc_pkt_len(skb);
459
460 return skb;
461 }
462
463 static void hhf_reset(struct Qdisc *sch)
464 {
465 struct sk_buff *skb;
466
467 while ((skb = hhf_dequeue(sch)) != NULL)
468 rtnl_kfree_skbs(skb, skb);
469 }
470
471 static void hhf_destroy(struct Qdisc *sch)
472 {
473 int i;
474 struct hhf_sched_data *q = qdisc_priv(sch);
475
476 for (i = 0; i < HHF_ARRAYS_CNT; i++) {
477 kvfree(q->hhf_arrays[i]);
478 kvfree(q->hhf_valid_bits[i]);
479 }
480
481 if (!q->hh_flows)
482 return;
483
484 for (i = 0; i < HH_FLOWS_CNT; i++) {
485 struct hh_flow_state *flow, *next;
486 struct list_head *head = &q->hh_flows[i];
487
488 if (list_empty(head))
489 continue;
490 list_for_each_entry_safe(flow, next, head, flowchain) {
491 list_del(&flow->flowchain);
492 kfree(flow);
493 }
494 }
495 kvfree(q->hh_flows);
496 }
497
498 static const struct nla_policy hhf_policy[TCA_HHF_MAX + 1] = {
499 [TCA_HHF_BACKLOG_LIMIT] = { .type = NLA_U32 },
500 [TCA_HHF_QUANTUM] = { .type = NLA_U32 },
501 [TCA_HHF_HH_FLOWS_LIMIT] = { .type = NLA_U32 },
502 [TCA_HHF_RESET_TIMEOUT] = { .type = NLA_U32 },
503 [TCA_HHF_ADMIT_BYTES] = { .type = NLA_U32 },
504 [TCA_HHF_EVICT_TIMEOUT] = { .type = NLA_U32 },
505 [TCA_HHF_NON_HH_WEIGHT] = { .type = NLA_U32 },
506 };
507
508 static int hhf_change(struct Qdisc *sch, struct nlattr *opt,
509 struct netlink_ext_ack *extack)
510 {
511 struct hhf_sched_data *q = qdisc_priv(sch);
512 struct nlattr *tb[TCA_HHF_MAX + 1];
513 unsigned int qlen, prev_backlog;
514 int err;
515 u64 non_hh_quantum;
516 u32 new_quantum = q->quantum;
517 u32 new_hhf_non_hh_weight = q->hhf_non_hh_weight;
518
519 if (!opt)
520 return -EINVAL;
521
522 err = nla_parse_nested_deprecated(tb, TCA_HHF_MAX, opt, hhf_policy,
523 NULL);
524 if (err < 0)
525 return err;
526
527 if (tb[TCA_HHF_QUANTUM])
528 new_quantum = nla_get_u32(tb[TCA_HHF_QUANTUM]);
529
530 if (tb[TCA_HHF_NON_HH_WEIGHT])
531 new_hhf_non_hh_weight = nla_get_u32(tb[TCA_HHF_NON_HH_WEIGHT]);
532
533 non_hh_quantum = (u64)new_quantum * new_hhf_non_hh_weight;
534 if (non_hh_quantum == 0 || non_hh_quantum > INT_MAX)
535 return -EINVAL;
536
537 sch_tree_lock(sch);
538
539 if (tb[TCA_HHF_BACKLOG_LIMIT])
540 sch->limit = nla_get_u32(tb[TCA_HHF_BACKLOG_LIMIT]);
541
542 q->quantum = new_quantum;
543 q->hhf_non_hh_weight = new_hhf_non_hh_weight;
544
545 if (tb[TCA_HHF_HH_FLOWS_LIMIT])
546 q->hh_flows_limit = nla_get_u32(tb[TCA_HHF_HH_FLOWS_LIMIT]);
547
548 if (tb[TCA_HHF_RESET_TIMEOUT]) {
549 u32 us = nla_get_u32(tb[TCA_HHF_RESET_TIMEOUT]);
550
551 q->hhf_reset_timeout = usecs_to_jiffies(us);
552 }
553
554 if (tb[TCA_HHF_ADMIT_BYTES])
555 q->hhf_admit_bytes = nla_get_u32(tb[TCA_HHF_ADMIT_BYTES]);
556
557 if (tb[TCA_HHF_EVICT_TIMEOUT]) {
558 u32 us = nla_get_u32(tb[TCA_HHF_EVICT_TIMEOUT]);
559
560 q->hhf_evict_timeout = usecs_to_jiffies(us);
561 }
562
563 qlen = sch->q.qlen;
564 prev_backlog = sch->qstats.backlog;
565 while (sch->q.qlen > sch->limit) {
566 struct sk_buff *skb = hhf_dequeue(sch);
567
568 rtnl_kfree_skbs(skb, skb);
569 }
570 qdisc_tree_reduce_backlog(sch, qlen - sch->q.qlen,
571 prev_backlog - sch->qstats.backlog);
572
573 sch_tree_unlock(sch);
574 return 0;
575 }
576
577 static int hhf_init(struct Qdisc *sch, struct nlattr *opt,
578 struct netlink_ext_ack *extack)
579 {
580 struct hhf_sched_data *q = qdisc_priv(sch);
581 int i;
582
583 sch->limit = 1000;
584 q->quantum = psched_mtu(qdisc_dev(sch));
585 get_random_bytes(&q->perturbation, sizeof(q->perturbation));
586 INIT_LIST_HEAD(&q->new_buckets);
587 INIT_LIST_HEAD(&q->old_buckets);
588
589 /* Configurable HHF parameters */
590 q->hhf_reset_timeout = HZ / 25; /* 40 ms */
591 q->hhf_admit_bytes = 131072; /* 128 KB */
592 q->hhf_evict_timeout = HZ; /* 1 sec */
593 q->hhf_non_hh_weight = 2;
594
595 if (opt) {
596 int err = hhf_change(sch, opt, extack);
597
598 if (err)
599 return err;
600 }
601
602 if (!q->hh_flows) {
603 /* Initialize heavy-hitter flow table. */
604 q->hh_flows = kvcalloc(HH_FLOWS_CNT, sizeof(struct list_head),
605 GFP_KERNEL);
606 if (!q->hh_flows)
607 return -ENOMEM;
608 for (i = 0; i < HH_FLOWS_CNT; i++)
609 INIT_LIST_HEAD(&q->hh_flows[i]);
610
611 /* Cap max active HHs at twice len of hh_flows table. */
612 q->hh_flows_limit = 2 * HH_FLOWS_CNT;
613 q->hh_flows_overlimit = 0;
614 q->hh_flows_total_cnt = 0;
615 q->hh_flows_current_cnt = 0;
616
617 /* Initialize heavy-hitter filter arrays. */
618 for (i = 0; i < HHF_ARRAYS_CNT; i++) {
619 q->hhf_arrays[i] = kvcalloc(HHF_ARRAYS_LEN,
620 sizeof(u32),
621 GFP_KERNEL);
622 if (!q->hhf_arrays[i]) {
623 /* Note: hhf_destroy() will be called
624 * by our caller.
625 */
626 return -ENOMEM;
627 }
628 }
629 q->hhf_arrays_reset_timestamp = hhf_time_stamp();
630
631 /* Initialize valid bits of heavy-hitter filter arrays. */
632 for (i = 0; i < HHF_ARRAYS_CNT; i++) {
633 q->hhf_valid_bits[i] = kvzalloc(HHF_ARRAYS_LEN /
634 BITS_PER_BYTE, GFP_KERNEL);
635 if (!q->hhf_valid_bits[i]) {
636 /* Note: hhf_destroy() will be called
637 * by our caller.
638 */
639 return -ENOMEM;
640 }
641 }
642
643 /* Initialize Weighted DRR buckets. */
644 for (i = 0; i < WDRR_BUCKET_CNT; i++) {
645 struct wdrr_bucket *bucket = q->buckets + i;
646
647 INIT_LIST_HEAD(&bucket->bucketchain);
648 }
649 }
650
651 return 0;
652 }
653
654 static int hhf_dump(struct Qdisc *sch, struct sk_buff *skb)
655 {
656 struct hhf_sched_data *q = qdisc_priv(sch);
657 struct nlattr *opts;
658
659 opts = nla_nest_start_noflag(skb, TCA_OPTIONS);
660 if (opts == NULL)
661 goto nla_put_failure;
662
663 if (nla_put_u32(skb, TCA_HHF_BACKLOG_LIMIT, sch->limit) ||
664 nla_put_u32(skb, TCA_HHF_QUANTUM, q->quantum) ||
665 nla_put_u32(skb, TCA_HHF_HH_FLOWS_LIMIT, q->hh_flows_limit) ||
666 nla_put_u32(skb, TCA_HHF_RESET_TIMEOUT,
667 jiffies_to_usecs(q->hhf_reset_timeout)) ||
668 nla_put_u32(skb, TCA_HHF_ADMIT_BYTES, q->hhf_admit_bytes) ||
669 nla_put_u32(skb, TCA_HHF_EVICT_TIMEOUT,
670 jiffies_to_usecs(q->hhf_evict_timeout)) ||
671 nla_put_u32(skb, TCA_HHF_NON_HH_WEIGHT, q->hhf_non_hh_weight))
672 goto nla_put_failure;
673
674 return nla_nest_end(skb, opts);
675
676 nla_put_failure:
677 return -1;
678 }
679
680 static int hhf_dump_stats(struct Qdisc *sch, struct gnet_dump *d)
681 {
682 struct hhf_sched_data *q = qdisc_priv(sch);
683 struct tc_hhf_xstats st = {
684 .drop_overlimit = q->drop_overlimit,
685 .hh_overlimit = q->hh_flows_overlimit,
686 .hh_tot_count = q->hh_flows_total_cnt,
687 .hh_cur_count = q->hh_flows_current_cnt,
688 };
689
690 return gnet_stats_copy_app(d, &st, sizeof(st));
691 }
692
693 static struct Qdisc_ops hhf_qdisc_ops __read_mostly = {
694 .id = "hhf",
695 .priv_size = sizeof(struct hhf_sched_data),
696
697 .enqueue = hhf_enqueue,
698 .dequeue = hhf_dequeue,
699 .peek = qdisc_peek_dequeued,
700 .init = hhf_init,
701 .reset = hhf_reset,
702 .destroy = hhf_destroy,
703 .change = hhf_change,
704 .dump = hhf_dump,
705 .dump_stats = hhf_dump_stats,
706 .owner = THIS_MODULE,
707 };
708
709 static int __init hhf_module_init(void)
710 {
711 return register_qdisc(&hhf_qdisc_ops);
712 }
713
714 static void __exit hhf_module_exit(void)
715 {
716 unregister_qdisc(&hhf_qdisc_ops);
717 }
718
719 module_init(hhf_module_init)
720 module_exit(hhf_module_exit)
721 MODULE_AUTHOR("Terry Lam");
722 MODULE_AUTHOR("Nandita Dukkipati");
723 MODULE_LICENSE("GPL");