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Terry Lam10239ed2013-12-15 00:30:21 -08001/* net/sched/sch_hhf.c Heavy-Hitter Filter (HHF)
2 *
3 * Copyright (C) 2013 Terry Lam <vtlam@google.com>
4 * Copyright (C) 2013 Nandita Dukkipati <nanditad@google.com>
5 */
6
7#include <linux/jhash.h>
8#include <linux/jiffies.h>
9#include <linux/module.h>
10#include <linux/skbuff.h>
11#include <linux/vmalloc.h>
12#include <net/flow_keys.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 */
104enum 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 */
113struct 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 */
120struct wdrr_bucket {
121 struct sk_buff *head;
122 struct sk_buff *tail;
123 struct list_head bucketchain;
124 int deficit;
125};
126
127struct hhf_sched_data {
128 struct wdrr_bucket buckets[WDRR_BUCKET_CNT];
129 u32 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
174static u32 hhf_time_stamp(void)
175{
176 return jiffies;
177}
178
179static unsigned int skb_hash(const struct hhf_sched_data *q,
180 const struct sk_buff *skb)
181{
182 struct flow_keys keys;
183 unsigned int hash;
184
185 if (skb->sk && skb->sk->sk_hash)
186 return skb->sk->sk_hash;
187
188 skb_flow_dissect(skb, &keys);
189 hash = jhash_3words((__force u32)keys.dst,
190 (__force u32)keys.src ^ keys.ip_proto,
191 (__force u32)keys.ports, q->perturbation);
192 return hash;
193}
194
195/* Looks up a heavy-hitter flow in a chaining list of table T. */
196static struct hh_flow_state *seek_list(const u32 hash,
197 struct list_head *head,
198 struct hhf_sched_data *q)
199{
200 struct hh_flow_state *flow, *next;
201 u32 now = hhf_time_stamp();
202
203 if (list_empty(head))
204 return NULL;
205
206 list_for_each_entry_safe(flow, next, head, flowchain) {
207 u32 prev = flow->hit_timestamp + q->hhf_evict_timeout;
208
209 if (hhf_time_before(prev, now)) {
210 /* Delete expired heavy-hitters, but preserve one entry
211 * to avoid kzalloc() when next time this slot is hit.
212 */
213 if (list_is_last(&flow->flowchain, head))
214 return NULL;
215 list_del(&flow->flowchain);
216 kfree(flow);
217 q->hh_flows_current_cnt--;
218 } else if (flow->hash_id == hash) {
219 return flow;
220 }
221 }
222 return NULL;
223}
224
225/* Returns a flow state entry for a new heavy-hitter. Either reuses an expired
226 * entry or dynamically alloc a new entry.
227 */
228static struct hh_flow_state *alloc_new_hh(struct list_head *head,
229 struct hhf_sched_data *q)
230{
231 struct hh_flow_state *flow;
232 u32 now = hhf_time_stamp();
233
234 if (!list_empty(head)) {
235 /* Find an expired heavy-hitter flow entry. */
236 list_for_each_entry(flow, head, flowchain) {
237 u32 prev = flow->hit_timestamp + q->hhf_evict_timeout;
238
239 if (hhf_time_before(prev, now))
240 return flow;
241 }
242 }
243
244 if (q->hh_flows_current_cnt >= q->hh_flows_limit) {
245 q->hh_flows_overlimit++;
246 return NULL;
247 }
248 /* Create new entry. */
249 flow = kzalloc(sizeof(struct hh_flow_state), GFP_ATOMIC);
250 if (!flow)
251 return NULL;
252
253 q->hh_flows_current_cnt++;
254 INIT_LIST_HEAD(&flow->flowchain);
255 list_add_tail(&flow->flowchain, head);
256
257 return flow;
258}
259
260/* Assigns packets to WDRR buckets. Implements a multi-stage filter to
261 * classify heavy-hitters.
262 */
263static enum wdrr_bucket_idx hhf_classify(struct sk_buff *skb, struct Qdisc *sch)
264{
265 struct hhf_sched_data *q = qdisc_priv(sch);
266 u32 tmp_hash, hash;
267 u32 xorsum, filter_pos[HHF_ARRAYS_CNT], flow_pos;
268 struct hh_flow_state *flow;
269 u32 pkt_len, min_hhf_val;
270 int i;
271 u32 prev;
272 u32 now = hhf_time_stamp();
273
274 /* Reset the HHF counter arrays if this is the right time. */
275 prev = q->hhf_arrays_reset_timestamp + q->hhf_reset_timeout;
276 if (hhf_time_before(prev, now)) {
277 for (i = 0; i < HHF_ARRAYS_CNT; i++)
278 bitmap_zero(q->hhf_valid_bits[i], HHF_ARRAYS_LEN);
279 q->hhf_arrays_reset_timestamp = now;
280 }
281
282 /* Get hashed flow-id of the skb. */
283 hash = skb_hash(q, skb);
284
285 /* Check if this packet belongs to an already established HH flow. */
286 flow_pos = hash & HHF_BIT_MASK;
287 flow = seek_list(hash, &q->hh_flows[flow_pos], q);
288 if (flow) { /* found its HH flow */
289 flow->hit_timestamp = now;
290 return WDRR_BUCKET_FOR_HH;
291 }
292
293 /* Now pass the packet through the multi-stage filter. */
294 tmp_hash = hash;
295 xorsum = 0;
296 for (i = 0; i < HHF_ARRAYS_CNT - 1; i++) {
297 /* Split the skb_hash into three 10-bit chunks. */
298 filter_pos[i] = tmp_hash & HHF_BIT_MASK;
299 xorsum ^= filter_pos[i];
300 tmp_hash >>= HHF_BIT_MASK_LEN;
301 }
302 /* The last chunk is computed as XOR sum of other chunks. */
303 filter_pos[HHF_ARRAYS_CNT - 1] = xorsum ^ tmp_hash;
304
305 pkt_len = qdisc_pkt_len(skb);
306 min_hhf_val = ~0U;
307 for (i = 0; i < HHF_ARRAYS_CNT; i++) {
308 u32 val;
309
310 if (!test_bit(filter_pos[i], q->hhf_valid_bits[i])) {
311 q->hhf_arrays[i][filter_pos[i]] = 0;
312 __set_bit(filter_pos[i], q->hhf_valid_bits[i]);
313 }
314
315 val = q->hhf_arrays[i][filter_pos[i]] + pkt_len;
316 if (min_hhf_val > val)
317 min_hhf_val = val;
318 }
319
320 /* Found a new HH iff all counter values > HH admit threshold. */
321 if (min_hhf_val > q->hhf_admit_bytes) {
322 /* Just captured a new heavy-hitter. */
323 flow = alloc_new_hh(&q->hh_flows[flow_pos], q);
324 if (!flow) /* memory alloc problem */
325 return WDRR_BUCKET_FOR_NON_HH;
326 flow->hash_id = hash;
327 flow->hit_timestamp = now;
328 q->hh_flows_total_cnt++;
329
330 /* By returning without updating counters in q->hhf_arrays,
331 * we implicitly implement "shielding" (see Optimization O1).
332 */
333 return WDRR_BUCKET_FOR_HH;
334 }
335
336 /* Conservative update of HHF arrays (see Optimization O2). */
337 for (i = 0; i < HHF_ARRAYS_CNT; i++) {
338 if (q->hhf_arrays[i][filter_pos[i]] < min_hhf_val)
339 q->hhf_arrays[i][filter_pos[i]] = min_hhf_val;
340 }
341 return WDRR_BUCKET_FOR_NON_HH;
342}
343
344/* Removes one skb from head of bucket. */
345static struct sk_buff *dequeue_head(struct wdrr_bucket *bucket)
346{
347 struct sk_buff *skb = bucket->head;
348
349 bucket->head = skb->next;
350 skb->next = NULL;
351 return skb;
352}
353
354/* Tail-adds skb to bucket. */
355static void bucket_add(struct wdrr_bucket *bucket, struct sk_buff *skb)
356{
357 if (bucket->head == NULL)
358 bucket->head = skb;
359 else
360 bucket->tail->next = skb;
361 bucket->tail = skb;
362 skb->next = NULL;
363}
364
365static unsigned int hhf_drop(struct Qdisc *sch)
366{
367 struct hhf_sched_data *q = qdisc_priv(sch);
368 struct wdrr_bucket *bucket;
369
370 /* Always try to drop from heavy-hitters first. */
371 bucket = &q->buckets[WDRR_BUCKET_FOR_HH];
372 if (!bucket->head)
373 bucket = &q->buckets[WDRR_BUCKET_FOR_NON_HH];
374
375 if (bucket->head) {
376 struct sk_buff *skb = dequeue_head(bucket);
377
378 sch->q.qlen--;
379 sch->qstats.drops++;
380 sch->qstats.backlog -= qdisc_pkt_len(skb);
381 kfree_skb(skb);
382 }
383
384 /* Return id of the bucket from which the packet was dropped. */
385 return bucket - q->buckets;
386}
387
388static int hhf_enqueue(struct sk_buff *skb, struct Qdisc *sch)
389{
390 struct hhf_sched_data *q = qdisc_priv(sch);
391 enum wdrr_bucket_idx idx;
392 struct wdrr_bucket *bucket;
393
394 idx = hhf_classify(skb, sch);
395
396 bucket = &q->buckets[idx];
397 bucket_add(bucket, skb);
398 sch->qstats.backlog += qdisc_pkt_len(skb);
399
400 if (list_empty(&bucket->bucketchain)) {
401 unsigned int weight;
402
403 /* The logic of new_buckets vs. old_buckets is the same as
404 * new_flows vs. old_flows in the implementation of fq_codel,
405 * i.e., short bursts of non-HHs should have strict priority.
406 */
407 if (idx == WDRR_BUCKET_FOR_HH) {
408 /* Always move heavy-hitters to old bucket. */
409 weight = 1;
410 list_add_tail(&bucket->bucketchain, &q->old_buckets);
411 } else {
412 weight = q->hhf_non_hh_weight;
413 list_add_tail(&bucket->bucketchain, &q->new_buckets);
414 }
415 bucket->deficit = weight * q->quantum;
416 }
Yang Yingliangb2ce49e72014-05-09 16:49:05 +0800417 if (++sch->q.qlen <= sch->limit)
Terry Lam10239ed2013-12-15 00:30:21 -0800418 return NET_XMIT_SUCCESS;
419
420 q->drop_overlimit++;
421 /* Return Congestion Notification only if we dropped a packet from this
422 * bucket.
423 */
424 if (hhf_drop(sch) == idx)
425 return NET_XMIT_CN;
426
427 /* As we dropped a packet, better let upper stack know this. */
428 qdisc_tree_decrease_qlen(sch, 1);
429 return NET_XMIT_SUCCESS;
430}
431
432static struct sk_buff *hhf_dequeue(struct Qdisc *sch)
433{
434 struct hhf_sched_data *q = qdisc_priv(sch);
435 struct sk_buff *skb = NULL;
436 struct wdrr_bucket *bucket;
437 struct list_head *head;
438
439begin:
440 head = &q->new_buckets;
441 if (list_empty(head)) {
442 head = &q->old_buckets;
443 if (list_empty(head))
444 return NULL;
445 }
446 bucket = list_first_entry(head, struct wdrr_bucket, bucketchain);
447
448 if (bucket->deficit <= 0) {
449 int weight = (bucket - q->buckets == WDRR_BUCKET_FOR_HH) ?
450 1 : q->hhf_non_hh_weight;
451
452 bucket->deficit += weight * q->quantum;
453 list_move_tail(&bucket->bucketchain, &q->old_buckets);
454 goto begin;
455 }
456
457 if (bucket->head) {
458 skb = dequeue_head(bucket);
459 sch->q.qlen--;
460 sch->qstats.backlog -= qdisc_pkt_len(skb);
461 }
462
463 if (!skb) {
464 /* Force a pass through old_buckets to prevent starvation. */
465 if ((head == &q->new_buckets) && !list_empty(&q->old_buckets))
466 list_move_tail(&bucket->bucketchain, &q->old_buckets);
467 else
468 list_del_init(&bucket->bucketchain);
469 goto begin;
470 }
471 qdisc_bstats_update(sch, skb);
472 bucket->deficit -= qdisc_pkt_len(skb);
473
474 return skb;
475}
476
477static void hhf_reset(struct Qdisc *sch)
478{
479 struct sk_buff *skb;
480
481 while ((skb = hhf_dequeue(sch)) != NULL)
482 kfree_skb(skb);
483}
484
485static void *hhf_zalloc(size_t sz)
486{
487 void *ptr = kzalloc(sz, GFP_KERNEL | __GFP_NOWARN);
488
489 if (!ptr)
490 ptr = vzalloc(sz);
491
492 return ptr;
493}
494
495static void hhf_free(void *addr)
496{
WANG Cong4cb28972014-06-02 15:55:22 -0700497 kvfree(addr);
Terry Lam10239ed2013-12-15 00:30:21 -0800498}
499
500static void hhf_destroy(struct Qdisc *sch)
501{
502 int i;
503 struct hhf_sched_data *q = qdisc_priv(sch);
504
505 for (i = 0; i < HHF_ARRAYS_CNT; i++) {
506 hhf_free(q->hhf_arrays[i]);
507 hhf_free(q->hhf_valid_bits[i]);
508 }
509
510 for (i = 0; i < HH_FLOWS_CNT; i++) {
511 struct hh_flow_state *flow, *next;
512 struct list_head *head = &q->hh_flows[i];
513
514 if (list_empty(head))
515 continue;
516 list_for_each_entry_safe(flow, next, head, flowchain) {
517 list_del(&flow->flowchain);
518 kfree(flow);
519 }
520 }
521 hhf_free(q->hh_flows);
522}
523
524static const struct nla_policy hhf_policy[TCA_HHF_MAX + 1] = {
525 [TCA_HHF_BACKLOG_LIMIT] = { .type = NLA_U32 },
526 [TCA_HHF_QUANTUM] = { .type = NLA_U32 },
527 [TCA_HHF_HH_FLOWS_LIMIT] = { .type = NLA_U32 },
528 [TCA_HHF_RESET_TIMEOUT] = { .type = NLA_U32 },
529 [TCA_HHF_ADMIT_BYTES] = { .type = NLA_U32 },
530 [TCA_HHF_EVICT_TIMEOUT] = { .type = NLA_U32 },
531 [TCA_HHF_NON_HH_WEIGHT] = { .type = NLA_U32 },
532};
533
534static int hhf_change(struct Qdisc *sch, struct nlattr *opt)
535{
536 struct hhf_sched_data *q = qdisc_priv(sch);
537 struct nlattr *tb[TCA_HHF_MAX + 1];
538 unsigned int qlen;
539 int err;
540 u64 non_hh_quantum;
541 u32 new_quantum = q->quantum;
542 u32 new_hhf_non_hh_weight = q->hhf_non_hh_weight;
543
544 if (!opt)
545 return -EINVAL;
546
547 err = nla_parse_nested(tb, TCA_HHF_MAX, opt, hhf_policy);
548 if (err < 0)
549 return err;
550
Terry Lam10239ed2013-12-15 00:30:21 -0800551 if (tb[TCA_HHF_QUANTUM])
552 new_quantum = nla_get_u32(tb[TCA_HHF_QUANTUM]);
553
554 if (tb[TCA_HHF_NON_HH_WEIGHT])
555 new_hhf_non_hh_weight = nla_get_u32(tb[TCA_HHF_NON_HH_WEIGHT]);
556
557 non_hh_quantum = (u64)new_quantum * new_hhf_non_hh_weight;
558 if (non_hh_quantum > INT_MAX)
559 return -EINVAL;
John Fastabendf6a082f2014-05-01 09:23:06 -0700560
561 sch_tree_lock(sch);
562
563 if (tb[TCA_HHF_BACKLOG_LIMIT])
564 sch->limit = nla_get_u32(tb[TCA_HHF_BACKLOG_LIMIT]);
565
Terry Lam10239ed2013-12-15 00:30:21 -0800566 q->quantum = new_quantum;
567 q->hhf_non_hh_weight = new_hhf_non_hh_weight;
568
569 if (tb[TCA_HHF_HH_FLOWS_LIMIT])
570 q->hh_flows_limit = nla_get_u32(tb[TCA_HHF_HH_FLOWS_LIMIT]);
571
572 if (tb[TCA_HHF_RESET_TIMEOUT]) {
Terry Lam6c76a072014-01-09 00:40:00 -0800573 u32 us = nla_get_u32(tb[TCA_HHF_RESET_TIMEOUT]);
Terry Lam10239ed2013-12-15 00:30:21 -0800574
Terry Lam6c76a072014-01-09 00:40:00 -0800575 q->hhf_reset_timeout = usecs_to_jiffies(us);
Terry Lam10239ed2013-12-15 00:30:21 -0800576 }
577
578 if (tb[TCA_HHF_ADMIT_BYTES])
579 q->hhf_admit_bytes = nla_get_u32(tb[TCA_HHF_ADMIT_BYTES]);
580
581 if (tb[TCA_HHF_EVICT_TIMEOUT]) {
Terry Lam6c76a072014-01-09 00:40:00 -0800582 u32 us = nla_get_u32(tb[TCA_HHF_EVICT_TIMEOUT]);
Terry Lam10239ed2013-12-15 00:30:21 -0800583
Terry Lam6c76a072014-01-09 00:40:00 -0800584 q->hhf_evict_timeout = usecs_to_jiffies(us);
Terry Lam10239ed2013-12-15 00:30:21 -0800585 }
586
587 qlen = sch->q.qlen;
588 while (sch->q.qlen > sch->limit) {
589 struct sk_buff *skb = hhf_dequeue(sch);
590
591 kfree_skb(skb);
592 }
593 qdisc_tree_decrease_qlen(sch, qlen - sch->q.qlen);
594
595 sch_tree_unlock(sch);
596 return 0;
597}
598
599static int hhf_init(struct Qdisc *sch, struct nlattr *opt)
600{
601 struct hhf_sched_data *q = qdisc_priv(sch);
602 int i;
603
604 sch->limit = 1000;
605 q->quantum = psched_mtu(qdisc_dev(sch));
Aruna-Hewapathirane63862b52014-01-11 07:15:59 -0500606 q->perturbation = prandom_u32();
Terry Lam10239ed2013-12-15 00:30:21 -0800607 INIT_LIST_HEAD(&q->new_buckets);
608 INIT_LIST_HEAD(&q->old_buckets);
609
610 /* Configurable HHF parameters */
611 q->hhf_reset_timeout = HZ / 25; /* 40 ms */
612 q->hhf_admit_bytes = 131072; /* 128 KB */
613 q->hhf_evict_timeout = HZ; /* 1 sec */
614 q->hhf_non_hh_weight = 2;
615
616 if (opt) {
617 int err = hhf_change(sch, opt);
618
619 if (err)
620 return err;
621 }
622
623 if (!q->hh_flows) {
624 /* Initialize heavy-hitter flow table. */
625 q->hh_flows = hhf_zalloc(HH_FLOWS_CNT *
626 sizeof(struct list_head));
627 if (!q->hh_flows)
628 return -ENOMEM;
629 for (i = 0; i < HH_FLOWS_CNT; i++)
630 INIT_LIST_HEAD(&q->hh_flows[i]);
631
632 /* Cap max active HHs at twice len of hh_flows table. */
633 q->hh_flows_limit = 2 * HH_FLOWS_CNT;
634 q->hh_flows_overlimit = 0;
635 q->hh_flows_total_cnt = 0;
636 q->hh_flows_current_cnt = 0;
637
638 /* Initialize heavy-hitter filter arrays. */
639 for (i = 0; i < HHF_ARRAYS_CNT; i++) {
640 q->hhf_arrays[i] = hhf_zalloc(HHF_ARRAYS_LEN *
641 sizeof(u32));
642 if (!q->hhf_arrays[i]) {
643 hhf_destroy(sch);
644 return -ENOMEM;
645 }
646 }
647 q->hhf_arrays_reset_timestamp = hhf_time_stamp();
648
649 /* Initialize valid bits of heavy-hitter filter arrays. */
650 for (i = 0; i < HHF_ARRAYS_CNT; i++) {
651 q->hhf_valid_bits[i] = hhf_zalloc(HHF_ARRAYS_LEN /
652 BITS_PER_BYTE);
653 if (!q->hhf_valid_bits[i]) {
654 hhf_destroy(sch);
655 return -ENOMEM;
656 }
657 }
658
659 /* Initialize Weighted DRR buckets. */
660 for (i = 0; i < WDRR_BUCKET_CNT; i++) {
661 struct wdrr_bucket *bucket = q->buckets + i;
662
663 INIT_LIST_HEAD(&bucket->bucketchain);
664 }
665 }
666
667 return 0;
668}
669
670static int hhf_dump(struct Qdisc *sch, struct sk_buff *skb)
671{
672 struct hhf_sched_data *q = qdisc_priv(sch);
673 struct nlattr *opts;
674
675 opts = nla_nest_start(skb, TCA_OPTIONS);
676 if (opts == NULL)
677 goto nla_put_failure;
678
679 if (nla_put_u32(skb, TCA_HHF_BACKLOG_LIMIT, sch->limit) ||
680 nla_put_u32(skb, TCA_HHF_QUANTUM, q->quantum) ||
681 nla_put_u32(skb, TCA_HHF_HH_FLOWS_LIMIT, q->hh_flows_limit) ||
682 nla_put_u32(skb, TCA_HHF_RESET_TIMEOUT,
Terry Lam6c76a072014-01-09 00:40:00 -0800683 jiffies_to_usecs(q->hhf_reset_timeout)) ||
Terry Lam10239ed2013-12-15 00:30:21 -0800684 nla_put_u32(skb, TCA_HHF_ADMIT_BYTES, q->hhf_admit_bytes) ||
685 nla_put_u32(skb, TCA_HHF_EVICT_TIMEOUT,
Terry Lam6c76a072014-01-09 00:40:00 -0800686 jiffies_to_usecs(q->hhf_evict_timeout)) ||
Terry Lam10239ed2013-12-15 00:30:21 -0800687 nla_put_u32(skb, TCA_HHF_NON_HH_WEIGHT, q->hhf_non_hh_weight))
688 goto nla_put_failure;
689
Yang Yingliangd59b7d82014-03-12 10:20:32 +0800690 return nla_nest_end(skb, opts);
Terry Lam10239ed2013-12-15 00:30:21 -0800691
692nla_put_failure:
693 return -1;
694}
695
696static int hhf_dump_stats(struct Qdisc *sch, struct gnet_dump *d)
697{
698 struct hhf_sched_data *q = qdisc_priv(sch);
699 struct tc_hhf_xstats st = {
700 .drop_overlimit = q->drop_overlimit,
701 .hh_overlimit = q->hh_flows_overlimit,
702 .hh_tot_count = q->hh_flows_total_cnt,
703 .hh_cur_count = q->hh_flows_current_cnt,
704 };
705
706 return gnet_stats_copy_app(d, &st, sizeof(st));
707}
708
stephen hemmingerc49fa252013-12-26 10:09:05 -0800709static struct Qdisc_ops hhf_qdisc_ops __read_mostly = {
Terry Lam10239ed2013-12-15 00:30:21 -0800710 .id = "hhf",
711 .priv_size = sizeof(struct hhf_sched_data),
712
713 .enqueue = hhf_enqueue,
714 .dequeue = hhf_dequeue,
715 .peek = qdisc_peek_dequeued,
716 .drop = hhf_drop,
717 .init = hhf_init,
718 .reset = hhf_reset,
719 .destroy = hhf_destroy,
720 .change = hhf_change,
721 .dump = hhf_dump,
722 .dump_stats = hhf_dump_stats,
723 .owner = THIS_MODULE,
724};
Terry Lam10239ed2013-12-15 00:30:21 -0800725
726static int __init hhf_module_init(void)
727{
728 return register_qdisc(&hhf_qdisc_ops);
729}
730
731static void __exit hhf_module_exit(void)
732{
733 unregister_qdisc(&hhf_qdisc_ops);
734}
735
736module_init(hhf_module_init)
737module_exit(hhf_module_exit)
738MODULE_AUTHOR("Terry Lam");
739MODULE_AUTHOR("Nandita Dukkipati");
740MODULE_LICENSE("GPL");