/* net/sched/sch_hhf.c Heavy-Hitter Filter (HHF)
*
* Copyright (C) 2013 Terry Lam <vtlam@google.com>
* Copyright (C) 2013 Nandita Dukkipati <nanditad@google.com>
*/
#include <linux/jhash.h>
#include <linux/jiffies.h>
#include <linux/module.h>
#include <linux/skbuff.h>
#include <linux/vmalloc.h>
#include <net/pkt_sched.h>
#include <net/sock.h>
/* Heavy-Hitter Filter (HHF)
*
* Principles :
* Flows are classified into two buckets: non-heavy-hitter and heavy-hitter
* buckets. Initially, a new flow starts as non-heavy-hitter. Once classified
* as heavy-hitter, it is immediately switched to the heavy-hitter bucket.
* The buckets are dequeued by a Weighted Deficit Round Robin (WDRR) scheduler,
* in which the heavy-hitter bucket is served with less weight.
* In other words, non-heavy-hitters (e.g., short bursts of critical traffic)
* are isolated from heavy-hitters (e.g., persistent bulk traffic) and also have
* higher share of bandwidth.
*
* To capture heavy-hitters, we use the "multi-stage filter" algorithm in the
* following paper:
* [EV02] C. Estan and G. Varghese, "New Directions in Traffic Measurement and
* Accounting", in ACM SIGCOMM, 2002.
*
* Conceptually, a multi-stage filter comprises k independent hash functions
* and k counter arrays. Packets are indexed into k counter arrays by k hash
* functions, respectively. The counters are then increased by the packet sizes.
* Therefore,
* - For a heavy-hitter flow: *all* of its k array counters must be large.
* - For a non-heavy-hitter flow: some of its k array counters can be large
* due to hash collision with other small flows; however, with high
* probability, not *all* k counters are large.
*
* By the design of the multi-stage filter algorithm, the false negative rate
* (heavy-hitters getting away uncaptured) is zero. However, the algorithm is
* susceptible to false positives (non-heavy-hitters mistakenly classified as
* heavy-hitters).
* Therefore, we also implement the following optimizations to reduce false
* positives by avoiding unnecessary increment of the counter values:
* - Optimization O1: once a heavy-hitter is identified, its bytes are not
* accounted in the array counters. This technique is called "shielding"
* in Section 3.3.1 of [EV02].
* - Optimization O2: conservative update of counters
* (Section 3.3.2 of [EV02]),
* New counter value = max {old counter value,
* smallest counter value + packet bytes}
*
* Finally, we refresh the counters periodically since otherwise the counter
* values will keep accumulating.
*
* Once a flow is classified as heavy-hitter, we also save its per-flow state
* in an exact-matching flow table so that its subsequent packets can be
* dispatched to the heavy-hitter bucket accordingly.
*
*
* At a high level, this qdisc works as follows:
* Given a packet p:
* - If the flow-id of p (e.g., TCP 5-tuple) is already in the exact-matching
* heavy-hitter flow table, denoted table T, then send p to the heavy-hitter
* bucket.
* - Otherwise, forward p to the multi-stage filter, denoted filter F
* + If F decides that p belongs to a non-heavy-hitter flow, then send p
* to the non-heavy-hitter bucket.
* + Otherwise, if F decides that p belongs to a new heavy-hitter flow,
* then set up a new flow entry for the flow-id of p in the table T and
* send p to the heavy-hitter bucket.
*
* In this implementation:
* - T is a fixed-size hash-table with 1024 entries. Hash collision is
* resolved by linked-list chaining.
* - F has four counter arrays, each array containing 1024 32-bit counters.
* That means 4 * 1024 * 32 bits = 16KB of memory.
* - Since each array in F contains 1024 counters, 10 bits are sufficient to
* index into each array.
* Hence, instead of having four hash functions, we chop the 32-bit
* skb-hash into three 10-bit chunks, and the remaining 10-bit chunk is
* computed as XOR sum of those three chunks.
* - We need to clear the counter arrays periodically; however, directly
* memsetting 16KB of memory can lead to cache eviction and unwanted delay.
* So by representing each counter by a valid bit, we only need to reset
* 4K of 1 bit (i.e. 512 bytes) instead of 16KB of memory.
* - The Deficit Round Robin engine is taken from fq_codel implementation
* (net/sched/sch_fq_codel.c). Note that wdrr_bucket corresponds to
* fq_codel_flow in fq_codel implementation.
*
*/
/* Non-configurable parameters */
#define HH_FLOWS_CNT 1024 /* number of entries in exact-matching table T */
#define HHF_ARRAYS_CNT 4 /* number of arrays in multi-stage filter F */
#define HHF_ARRAYS_LEN 1024 /* number of counters in each array of F */
#define HHF_BIT_MASK_LEN 10 /* masking 10 bits */
#define HHF_BIT_MASK 0x3FF /* bitmask of 10 bits */
#define WDRR_BUCKET_CNT 2 /* two buckets for Weighted DRR */
enum wdrr_bucket_idx {
WDRR_BUCKET_FOR_HH = 0, /* bucket id for heavy-hitters */
WDRR_BUCKET_FOR_NON_HH = 1 /* bucket id for non-heavy-hitters */
};
#define hhf_time_before(a, b) \
(typecheck(u32, a) && typecheck(u32, b) && ((s32)((a) - (b)) < 0))
/* Heavy-hitter per-flow state */
struct hh_flow_state {
u32 hash_id; /* hash of flow-id (e.g. TCP 5-tuple) */
u32 hit_timestamp; /* last time heavy-hitter was seen */
struct list_head flowchain; /* chaining under hash collision */
};
/* Weighted Deficit Round Robin (WDRR) scheduler */
struct wdrr_bucket {
struct sk_buff *head;
struct sk_buff *tail;
struct list_head bucketchain;
int deficit;
};
struct hhf_sched_data {
struct wdrr_bucket buckets[WDRR_BUCKET_CNT];
u32 perturbation; /* hash perturbation */
u32 quantum; /* psched_mtu(qdisc_dev(sch)); */
u32 drop_overlimit; /* number of times max qdisc packet
* limit was hit
*/
struct list_head *hh_flows; /* table T (currently active HHs) */
u32 hh_flows_limit; /* max active HH allocs */
u32 hh_flows_overlimit; /* num of disallowed HH allocs */
u32 hh_flows_total_cnt; /* total admitted HHs */
u32 hh_flows_current_cnt; /* total current HHs */
u32 *hhf_arrays[HHF_ARRAYS_CNT]; /* HH filter F */
u32 hhf_arrays_reset_timestamp; /* last time hhf_arrays
* was reset
*/
unsigned long *hhf_valid_bits[HHF_ARRAYS_CNT]; /* shadow valid bits
* of hhf_arrays
*/
/* Similar to the "new_flows" vs. "old_flows" concept in fq_codel DRR */
struct list_head new_buckets; /* list of new buckets */
struct list_head old_buckets; /* list of old buckets */
/* Configurable HHF parameters */
u32 hhf_reset_timeout; /* interval to reset counter
* arrays in filter F
* (default 40ms)
*/
u32 hhf_admit_bytes; /* counter thresh to classify as
* HH (default 128KB).
* With these default values,
* 128KB / 40ms = 25 Mbps
* i.e., we expect to capture HHs
* sending > 25 Mbps.
*/
u32 hhf_evict_timeout; /* aging threshold to evict idle
* HHs out of table T. This should
* be large enough to avoid
* reordering during HH eviction.
* (default 1s)
*/
u32 hhf_non_hh_weight; /* WDRR weight for non-HHs
* (default 2,
* i.e., non-HH : HH = 2 : 1)
*/
};
static u32 hhf_time_stamp(void)
{
return jiffies;
}
/* Looks up a heavy-hitter flow in a chaining list of table T. */
static struct hh_flow_state *seek_list(const u32 hash,
struct list_head *head,
struct hhf_sched_data *q)
{
struct hh_flow_state *flow, *next;
u32 now = hhf_time_stamp();
if (list_empty(head))
return NULL;
list_for_each_entry_safe(flow, next, head, flowchain) {
u32 prev = flow->hit_timestamp + q->hhf_evict_timeout;
if (hhf_time_before(prev, now)) {
/* Delete expired heavy-hitters, but preserve one entry
* to avoid kzalloc() when next time this slot is hit.
*/
if (list_is_last(&flow->flowchain, head))
return NULL;
list_del(&flow->flowchain);
kfree(flow);
q->hh_flows_current_cnt--;
} else if (flow->hash_id == hash) {
return flow;
}
}
return NULL;
}
/* Returns a flow state entry for a new heavy-hitter. Either reuses an expired
* entry or dynamically alloc a new entry.
*/
static struct hh_flow_state *alloc_new_hh(struct list_head *head,
struct hhf_sched_data *q)
{
struct hh_flow_state *flow;
u32 now = hhf_time_stamp();
if (!list_empty(head)) {
/* Find an expired heavy-hitter flow entry. */
list_for_each_entry(flow, head, flowchain) {
u32 prev = flow->hit_timestamp + q->hhf_evict_timeout;
if (hhf_time_before(prev, now))
return flow;
}
}
if (q->hh_flows_current_cnt >= q->hh_flows_limit) {
q->hh_flows_overlimit++;
return NULL;
}
/* Create new entry. */
flow = kzalloc(sizeof(struct hh_flow_state), GFP_ATOMIC);
if (!flow)
return NULL;
q->hh_flows_current_cnt++;
INIT_LIST_HEAD(&flow->flowchain);
list_add_tail(&flow->flowchain, head);
return flow;
}
/* Assigns packets to WDRR buckets. Implements a multi-stage filter to
* classify heavy-hitters.
*/
static enum wdrr_bucket_idx hhf_classify(struct sk_buff *skb, struct Qdisc *sch)
{
struct hhf_sched_data *q = qdisc_priv(sch);
u32 tmp_hash, hash;
u32 xorsum, filter_pos[HHF_ARRAYS_CNT], flow_pos;
struct hh_flow_state *flow;
u32 pkt_len, min_hhf_val;
int i;
u32 prev;
u32 now = hhf_time_stamp();
/* Reset the HHF counter arrays if this is the right time. */
prev = q->hhf_arrays_reset_timestamp + q->hhf_reset_timeout;
if (hhf_time_before(prev, now)) {
for (i = 0; i < HHF_ARRAYS_CNT; i++)
bitmap_zero(q->hhf_valid_bits[i], HHF_ARRAYS_LEN);
q->hhf_arrays_reset_timestamp = now;
}
/* Get hashed flow-id of the skb. */
hash = skb_get_hash_perturb(skb, q->perturbation);
/* Check if this packet belongs to an already established HH flow. */
flow_pos = hash & HHF_BIT_MASK;
flow = seek_list(hash, &q->hh_flows[flow_pos], q);
if (flow) { /* found its HH flow */
flow->hit_timestamp = now;
return WDRR_BUCKET_FOR_HH;
}
/* Now pass the packet through the multi-stage filter. */
tmp_hash = hash;
xorsum = 0;
for (i = 0; i < HHF_ARRAYS_CNT - 1; i++) {
/* Split the skb_hash into three 10-bit chunks. */
filter_pos[i] = tmp_hash & HHF_BIT_MASK;
xorsum ^= filter_pos[i];
tmp_hash >>= HHF_BIT_MASK_LEN;
}
/* The last chunk is computed as XOR sum of other chunks. */
filter_pos[HHF_ARRAYS_CNT - 1] = xorsum ^ tmp_hash;
pkt_len = qdisc_pkt_len(skb);
min_hhf_val = ~0U;
for (i = 0; i < HHF_ARRAYS_CNT; i++) {
u32 val;
if (!test_bit(filter_pos[i], q->hhf_valid_bits[i])) {
q->hhf_arrays[i][filter_pos[i]] = 0;
__set_bit(filter_pos[i], q->hhf_valid_bits[i]);
}
val = q->hhf_arrays[i][filter_pos[i]] + pkt_len;
if (min_hhf_val > val)
min_hhf_val = val;
}
/* Found a new HH iff all counter values > HH admit threshold. */
if (min_hhf_val > q->hhf_admit_bytes) {
/* Just captured a new heavy-hitter. */
flow = alloc_new_hh(&q->hh_flows[flow_pos], q);
if (!flow) /* memory alloc problem */
return WDRR_BUCKET_FOR_NON_HH;
flow->hash_id = hash;
flow->hit_timestamp = now;
q->hh_flows_total_cnt++;
/* By returning without updating counters in q->hhf_arrays,
* we implicitly implement "shielding" (see Optimization O1).
*/
return WDRR_BUCKET_FOR_HH;
}
/* Conservative update of HHF arrays (see Optimization O2). */
for (i = 0; i < HHF_ARRAYS_CNT; i++) {
if (q->hhf_arrays[i][filter_pos[i]] < min_hhf_val)
q->hhf_arrays[i][filter_pos[i]] = min_hhf_val;
}
return WDRR_BUCKET_FOR_NON_HH;
}
/* Removes one skb from head of bucket. */
static struct sk_buff *dequeue_head(struct wdrr_bucket *bucket)
{
struct sk_buff *skb = bucket->head;
bucket->head = skb->next;
skb->next = NULL;
return skb;
}
/* Tail-adds skb to bucket. */
static void bucket_add(struct wdrr_bucket *bucket, struct sk_buff *skb)
{
if (bucket->head == NULL)
bucket->head = skb;
else
bucket->tail->next = skb;
bucket->tail = skb;
skb->next = NULL;
}
static unsigned int hhf_drop(struct Qdisc *sch)
{
struct hhf_sched_data *q = qdisc_priv(sch);
struct wdrr_bucket *bucket;
/* Always try to drop from heavy-hitters first. */
bucket = &q->buckets[WDRR_BUCKET_FOR_HH];
if (!bucket->head)
bucket = &q->buckets[WDRR_BUCKET_FOR_NON_HH];
if (bucket->head) {
struct sk_buff *skb = dequeue_head(bucket);
sch->q.qlen--;
qdisc_qstats_drop(sch);
qdisc_qstats_backlog_dec(sch, skb);
kfree_skb(skb);
}
/* Return id of the bucket from which the packet was dropped. */
return bucket - q->buckets;
}
static unsigned int hhf_qdisc_drop(struct Qdisc *sch)
{
unsigned int prev_backlog;
prev_backlog = sch->qstats.backlog;
hhf_drop(sch);
return prev_backlog - sch->qstats.backlog;
}
static int hhf_enqueue(struct sk_buff *skb, struct Qdisc *sch)
{
struct hhf_sched_data *q = qdisc_priv(sch);
enum wdrr_bucket_idx idx;
struct wdrr_bucket *bucket;
idx = hhf_classify(skb, sch);
bucket = &q->buckets[idx];
bucket_add(bucket, skb);
qdisc_qstats_backlog_inc(sch, skb);
if (list_empty(&bucket->bucketchain)) {
unsigned int weight;
/* The logic of new_buckets vs. old_buckets is the same as
* new_flows vs. old_flows in the implementation of fq_codel,
* i.e., short bursts of non-HHs should have strict priority.
*/
if (idx == WDRR_BUCKET_FOR_HH) {
/* Always move heavy-hitters to old bucket. */
weight = 1;
list_add_tail(&bucket->bucketchain, &q->old_buckets);
} else {
weight = q->hhf_non_hh_weight;
list_add_tail(&bucket->bucketchain, &q->new_buckets);
}
bucket->deficit = weight * q->quantum;
}
if (++sch->q.qlen <= sch->limit)
return NET_XMIT_SUCCESS;
q->drop_overlimit++;
/* Return Congestion Notification only if we dropped a packet from this
* bucket.
*/
if (hhf_drop(sch) == idx)
return NET_XMIT_CN;
/* As we dropped a packet, better let upper stack know this. */
qdisc_tree_decrease_qlen(sch, 1);
return NET_XMIT_SUCCESS;
}
static struct sk_buff *hhf_dequeue(struct Qdisc *sch)
{
struct hhf_sched_data *q = qdisc_priv(sch);
struct sk_buff *skb = NULL;
struct wdrr_bucket *bucket;
struct list_head *head;
begin:
head = &q->new_buckets;
if (list_empty(head)) {
head = &q->old_buckets;
if (list_empty(head))
return NULL;
}
bucket = list_first_entry(head, struct wdrr_bucket, bucketchain);
if (bucket->deficit <= 0) {
int weight = (bucket - q->buckets == WDRR_BUCKET_FOR_HH) ?
1 : q->hhf_non_hh_weight;
bucket->deficit += weight * q->quantum;
list_move_tail(&bucket->bucketchain, &q->old_buckets);
goto begin;
}
if (bucket->head) {
skb = dequeue_head(bucket);
sch->q.qlen--;
qdisc_qstats_backlog_dec(sch, skb);
}
if (!skb) {
/* Force a pass through old_buckets to prevent starvation. */
if ((head == &q->new_buckets) && !list_empty(&q->old_buckets))
list_move_tail(&bucket->bucketchain, &q->old_buckets);
else
list_del_init(&bucket->bucketchain);
goto begin;
}
qdisc_bstats_update(sch, skb);
bucket->deficit -= qdisc_pkt_len(skb);
return skb;
}
static void hhf_reset(struct Qdisc *sch)
{
struct sk_buff *skb;
while ((skb = hhf_dequeue(sch)) != NULL)
kfree_skb(skb);
}
static void *hhf_zalloc(size_t sz)
{
void *ptr = kzalloc(sz, GFP_KERNEL | __GFP_NOWARN);
if (!ptr)
ptr = vzalloc(sz);
return ptr;
}
static void hhf_free(void *addr)
{
kvfree(addr);
}
static void hhf_destroy(struct Qdisc *sch)
{
int i;
struct hhf_sched_data *q = qdisc_priv(sch);
for (i = 0; i < HHF_ARRAYS_CNT; i++) {
hhf_free(q->hhf_arrays[i]);
hhf_free(q->hhf_valid_bits[i]);
}
for (i = 0; i < HH_FLOWS_CNT; i++) {
struct hh_flow_state *flow, *next;
struct list_head *head = &q->hh_flows[i];
if (list_empty(head))
continue;
list_for_each_entry_safe(flow, next, head, flowchain) {
list_del(&flow->flowchain);
kfree(flow);
}
}
hhf_free(q->hh_flows);
}
static const struct nla_policy hhf_policy[TCA_HHF_MAX + 1] = {
[TCA_HHF_BACKLOG_LIMIT] = { .type = NLA_U32 },
[TCA_HHF_QUANTUM] = { .type = NLA_U32 },
[TCA_HHF_HH_FLOWS_LIMIT] = { .type = NLA_U32 },
[TCA_HHF_RESET_TIMEOUT] = { .type = NLA_U32 },
[TCA_HHF_ADMIT_BYTES] = { .type = NLA_U32 },
[TCA_HHF_EVICT_TIMEOUT] = { .type = NLA_U32 },
[TCA_HHF_NON_HH_WEIGHT] = { .type = NLA_U32 },
};
static int hhf_change(struct Qdisc *sch, struct nlattr *opt)
{
struct hhf_sched_data *q = qdisc_priv(sch);
struct nlattr *tb[TCA_HHF_MAX + 1];
unsigned int qlen;
int err;
u64 non_hh_quantum;
u32 new_quantum = q->quantum;
u32 new_hhf_non_hh_weight = q->hhf_non_hh_weight;
if (!opt)
return -EINVAL;
err = nla_parse_nested(tb, TCA_HHF_MAX, opt, hhf_policy);
if (err < 0)
return err;
if (tb[TCA_HHF_QUANTUM])
new_quantum = nla_get_u32(tb[TCA_HHF_QUANTUM]);
if (tb[TCA_HHF_NON_HH_WEIGHT])
new_hhf_non_hh_weight = nla_get_u32(tb[TCA_HHF_NON_HH_WEIGHT]);
non_hh_quantum = (u64)new_quantum * new_hhf_non_hh_weight;
if (non_hh_quantum > INT_MAX)
return -EINVAL;
sch_tree_lock(sch);
if (tb[TCA_HHF_BACKLOG_LIMIT])
sch->limit = nla_get_u32(tb[TCA_HHF_BACKLOG_LIMIT]);
q->quantum = new_quantum;
q->hhf_non_hh_weight = new_hhf_non_hh_weight;
if (tb[TCA_HHF_HH_FLOWS_LIMIT])
q->hh_flows_limit = nla_get_u32(tb[TCA_HHF_HH_FLOWS_LIMIT]);
if (tb[TCA_HHF_RESET_TIMEOUT]) {
u32 us = nla_get_u32(tb[TCA_HHF_RESET_TIMEOUT]);
q->hhf_reset_timeout = usecs_to_jiffies(us);
}
if (tb[TCA_HHF_ADMIT_BYTES])
q->hhf_admit_bytes = nla_get_u32(tb[TCA_HHF_ADMIT_BYTES]);
if (tb[TCA_HHF_EVICT_TIMEOUT]) {
u32 us = nla_get_u32(tb[TCA_HHF_EVICT_TIMEOUT]);
q->hhf_evict_timeout = usecs_to_jiffies(us);
}
qlen = sch->q.qlen;
while (sch->q.qlen > sch->limit) {
struct sk_buff *skb = hhf_dequeue(sch);
kfree_skb(skb);
}
qdisc_tree_decrease_qlen(sch, qlen - sch->q.qlen);
sch_tree_unlock(sch);
return 0;
}
static int hhf_init(struct Qdisc *sch, struct nlattr *opt)
{
struct hhf_sched_data *q = qdisc_priv(sch);
int i;
sch->limit = 1000;
q->quantum = psched_mtu(qdisc_dev(sch));
q->perturbation = prandom_u32();
INIT_LIST_HEAD(&q->new_buckets);
INIT_LIST_HEAD(&q->old_buckets);
/* Configurable HHF parameters */
q->hhf_reset_timeout = HZ / 25; /* 40 ms */
q->hhf_admit_bytes = 131072; /* 128 KB */
q->hhf_evict_timeout = HZ; /* 1 sec */
q->hhf_non_hh_weight = 2;
if (opt) {
int err = hhf_change(sch, opt);
if (err)
return err;
}
if (!q->hh_flows) {
/* Initialize heavy-hitter flow table. */
q->hh_flows = hhf_zalloc(HH_FLOWS_CNT *
sizeof(struct list_head));
if (!q->hh_flows)
return -ENOMEM;
for (i = 0; i < HH_FLOWS_CNT; i++)
INIT_LIST_HEAD(&q->hh_flows[i]);
/* Cap max active HHs at twice len of hh_flows table. */
q->hh_flows_limit = 2 * HH_FLOWS_CNT;
q->hh_flows_overlimit = 0;
q->hh_flows_total_cnt = 0;
q->hh_flows_current_cnt = 0;
/* Initialize heavy-hitter filter arrays. */
for (i = 0; i < HHF_ARRAYS_CNT; i++) {
q->hhf_arrays[i] = hhf_zalloc(HHF_ARRAYS_LEN *
sizeof(u32));
if (!q->hhf_arrays[i]) {
hhf_destroy(sch);
return -ENOMEM;
}
}
q->hhf_arrays_reset_timestamp = hhf_time_stamp();
/* Initialize valid bits of heavy-hitter filter arrays. */
for (i = 0; i < HHF_ARRAYS_CNT; i++) {
q->hhf_valid_bits[i] = hhf_zalloc(HHF_ARRAYS_LEN /
BITS_PER_BYTE);
if (!q->hhf_valid_bits[i]) {
hhf_destroy(sch);
return -ENOMEM;
}
}
/* Initialize Weighted DRR buckets. */
for (i = 0; i < WDRR_BUCKET_CNT; i++) {
struct wdrr_bucket *bucket = q->buckets + i;
INIT_LIST_HEAD(&bucket->bucketchain);
}
}
return 0;
}
static int hhf_dump(struct Qdisc *sch, struct sk_buff *skb)
{
struct hhf_sched_data *q = qdisc_priv(sch);
struct nlattr *opts;
opts = nla_nest_start(skb, TCA_OPTIONS);
if (opts == NULL)
goto nla_put_failure;
if (nla_put_u32(skb, TCA_HHF_BACKLOG_LIMIT, sch->limit) ||
nla_put_u32(skb, TCA_HHF_QUANTUM, q->quantum) ||
nla_put_u32(skb, TCA_HHF_HH_FLOWS_LIMIT, q->hh_flows_limit) ||
nla_put_u32(skb, TCA_HHF_RESET_TIMEOUT,
jiffies_to_usecs(q->hhf_reset_timeout)) ||
nla_put_u32(skb, TCA_HHF_ADMIT_BYTES, q->hhf_admit_bytes) ||
nla_put_u32(skb, TCA_HHF_EVICT_TIMEOUT,
jiffies_to_usecs(q->hhf_evict_timeout)) ||
nla_put_u32(skb, TCA_HHF_NON_HH_WEIGHT, q->hhf_non_hh_weight))
goto nla_put_failure;
return nla_nest_end(skb, opts);
nla_put_failure:
return -1;
}
static int hhf_dump_stats(struct Qdisc *sch, struct gnet_dump *d)
{
struct hhf_sched_data *q = qdisc_priv(sch);
struct tc_hhf_xstats st = {
.drop_overlimit = q->drop_overlimit,
.hh_overlimit = q->hh_flows_overlimit,
.hh_tot_count = q->hh_flows_total_cnt,
.hh_cur_count = q->hh_flows_current_cnt,
};
return gnet_stats_copy_app(d, &st, sizeof(st));
}
static struct Qdisc_ops hhf_qdisc_ops __read_mostly = {
.id = "hhf",
.priv_size = sizeof(struct hhf_sched_data),
.enqueue = hhf_enqueue,
.dequeue = hhf_dequeue,
.peek = qdisc_peek_dequeued,
.drop = hhf_qdisc_drop,
.init = hhf_init,
.reset = hhf_reset,
.destroy = hhf_destroy,
.change = hhf_change,
.dump = hhf_dump,
.dump_stats = hhf_dump_stats,
.owner = THIS_MODULE,
};
static int __init hhf_module_init(void)
{
return register_qdisc(&hhf_qdisc_ops);
}
static void __exit hhf_module_exit(void)
{
unregister_qdisc(&hhf_qdisc_ops);
}
module_init(hhf_module_init)
module_exit(hhf_module_exit)
MODULE_AUTHOR("Terry Lam");
MODULE_AUTHOR("Nandita Dukkipati");
MODULE_LICENSE("GPL");