SFQ is superior for this purpose.
IMPLEMENTATION:
- This implementation limits maximal queue length to 128;
- max mtu to 2^18-1; max 128 flows, number of hash buckets to 1024.
- The only goal of this restrictions was that all data
- fit into one 4K page on 32bit arches.
+ This implementation limits :
+ - maximal queue length per flow to 127 packets.
+ - max mtu to 2^18-1;
+ - max 65408 flows,
+ - number of hash buckets to 65536.
It is easy to increase these values, but not in flight. */
-#define SFQ_DEPTH 128 /* max number of packets per flow */
-#define SFQ_SLOTS 128 /* max number of flows */
-#define SFQ_EMPTY_SLOT 255
+#define SFQ_MAX_DEPTH 127 /* max number of packets per flow */
+#define SFQ_DEFAULT_FLOWS 128
+#define SFQ_MAX_FLOWS (0x10000 - SFQ_MAX_DEPTH - 1) /* max number of flows */
+#define SFQ_EMPTY_SLOT 0xffff
#define SFQ_DEFAULT_HASH_DIVISOR 1024
/* We use 16 bits to store allot, and want to handle packets up to 64K
#define SFQ_ALLOT_SHIFT 3
#define SFQ_ALLOT_SIZE(X) DIV_ROUND_UP(X, 1 << SFQ_ALLOT_SHIFT)
-/* This type should contain at least SFQ_DEPTH + SFQ_SLOTS values */
-typedef unsigned char sfq_index;
+/* This type should contain at least SFQ_MAX_DEPTH + 1 + SFQ_MAX_FLOWS values */
+typedef u16 sfq_index;
/*
* We dont use pointers to save space.
- * Small indexes [0 ... SFQ_SLOTS - 1] are 'pointers' to slots[] array
- * while following values [SFQ_SLOTS ... SFQ_SLOTS + SFQ_DEPTH - 1]
+ * Small indexes [0 ... SFQ_MAX_FLOWS - 1] are 'pointers' to slots[] array
+ * while following values [SFQ_MAX_FLOWS ... SFQ_MAX_FLOWS + SFQ_MAX_DEPTH]
* are 'pointers' to dep[] array
*/
struct sfq_head {
struct sk_buff *skblist_next;
struct sk_buff *skblist_prev;
sfq_index qlen; /* number of skbs in skblist */
- sfq_index next; /* next slot in sfq chain */
+ sfq_index next; /* next slot in sfq RR chain */
struct sfq_head dep; /* anchor in dep[] chains */
unsigned short hash; /* hash value (index in ht[]) */
short allot; /* credit for this slot */
};
struct sfq_sched_data {
-/* Parameters */
- int perturb_period;
- unsigned int quantum; /* Allotment per round: MUST BE >= MTU */
- int limit;
+/* frequently used fields */
+ int limit; /* limit of total number of packets in this qdisc */
unsigned int divisor; /* number of slots in hash table */
-/* Variables */
- struct tcf_proto *filter_list;
- struct timer_list perturb_timer;
+ unsigned int maxflows; /* number of flows in flows array */
+ int headdrop;
+ int maxdepth; /* limit of packets per flow */
+
u32 perturbation;
+ struct tcf_proto *filter_list;
sfq_index cur_depth; /* depth of longest slot */
unsigned short scaled_quantum; /* SFQ_ALLOT_SIZE(quantum) */
struct sfq_slot *tail; /* current slot in round */
- sfq_index *ht; /* Hash table (divisor slots) */
- struct sfq_slot slots[SFQ_SLOTS];
- struct sfq_head dep[SFQ_DEPTH]; /* Linked list of slots, indexed by depth */
+ sfq_index *ht; /* Hash table ('divisor' slots) */
+ struct sfq_slot *slots; /* Flows table ('maxflows' entries) */
+
+ struct sfq_head dep[SFQ_MAX_DEPTH + 1];
+ /* Linked lists of slots, indexed by depth
+ * dep[0] : list of unused flows
+ * dep[1] : list of flows with 1 packet
+ * dep[X] : list of flows with X packets
+ */
+
+ int perturb_period;
+ unsigned int quantum; /* Allotment per round: MUST BE >= MTU */
+ struct timer_list perturb_timer;
};
/*
*/
static inline struct sfq_head *sfq_dep_head(struct sfq_sched_data *q, sfq_index val)
{
- if (val < SFQ_SLOTS)
+ if (val < SFQ_MAX_FLOWS)
return &q->slots[val].dep;
- return &q->dep[val - SFQ_SLOTS];
+ return &q->dep[val - SFQ_MAX_FLOWS];
}
/*
}
/*
- * x : slot number [0 .. SFQ_SLOTS - 1]
+ * x : slot number [0 .. SFQ_MAX_FLOWS - 1]
*/
static inline void sfq_link(struct sfq_sched_data *q, sfq_index x)
{
sfq_index p, n;
- int qlen = q->slots[x].qlen;
+ struct sfq_slot *slot = &q->slots[x];
+ int qlen = slot->qlen;
- p = qlen + SFQ_SLOTS;
+ p = qlen + SFQ_MAX_FLOWS;
n = q->dep[qlen].next;
- q->slots[x].dep.next = n;
- q->slots[x].dep.prev = p;
+ slot->dep.next = n;
+ slot->dep.prev = p;
q->dep[qlen].next = x; /* sfq_dep_head(q, p)->next = x */
sfq_dep_head(q, n)->prev = x;
static inline void slot_queue_init(struct sfq_slot *slot)
{
+ memset(slot, 0, sizeof(*slot));
slot->skblist_prev = slot->skblist_next = (struct sk_buff *)slot;
}
x = q->dep[d].next;
slot = &q->slots[x];
drop:
- skb = slot_dequeue_tail(slot);
+ skb = q->headdrop ? slot_dequeue_head(slot) : slot_dequeue_tail(slot);
len = qdisc_pkt_len(skb);
sfq_dec(q, x);
kfree_skb(skb);
slot = &q->slots[x];
if (x == SFQ_EMPTY_SLOT) {
x = q->dep[0].next; /* get a free slot */
+ if (x >= SFQ_MAX_FLOWS)
+ return qdisc_drop(skb, sch);
q->ht[hash] = x;
slot = &q->slots[x];
slot->hash = hash;
}
- /* If selected queue has length q->limit, do simple tail drop,
- * i.e. drop _this_ packet.
- */
- if (slot->qlen >= q->limit)
- return qdisc_drop(skb, sch);
+ if (slot->qlen >= q->maxdepth) {
+ struct sk_buff *head;
+
+ if (!q->headdrop)
+ return qdisc_drop(skb, sch);
+
+ head = slot_dequeue_head(slot);
+ sch->qstats.backlog -= qdisc_pkt_len(head);
+ qdisc_drop(head, sch);
+
+ sch->qstats.backlog += qdisc_pkt_len(skb);
+ slot_queue_add(slot, skb);
+ return NET_XMIT_CN;
+ }
sch->qstats.backlog += qdisc_pkt_len(skb);
slot_queue_add(slot, skb);
* We dont use sfq_dequeue()/sfq_enqueue() because we dont want to change
* counters.
*/
-static void sfq_rehash(struct sfq_sched_data *q)
+static void sfq_rehash(struct Qdisc *sch)
{
+ struct sfq_sched_data *q = qdisc_priv(sch);
struct sk_buff *skb;
int i;
struct sfq_slot *slot;
struct sk_buff_head list;
+ int dropped = 0;
__skb_queue_head_init(&list);
- for (i = 0; i < SFQ_SLOTS; i++) {
+ for (i = 0; i < q->maxflows; i++) {
slot = &q->slots[i];
if (!slot->qlen)
continue;
slot = &q->slots[x];
if (x == SFQ_EMPTY_SLOT) {
x = q->dep[0].next; /* get a free slot */
+ if (x >= SFQ_MAX_FLOWS) {
+drop: sch->qstats.backlog -= qdisc_pkt_len(skb);
+ kfree_skb(skb);
+ dropped++;
+ continue;
+ }
q->ht[hash] = x;
slot = &q->slots[x];
slot->hash = hash;
}
+ if (slot->qlen >= q->maxdepth)
+ goto drop;
slot_queue_add(slot, skb);
sfq_inc(q, x);
if (slot->qlen == 1) { /* The flow is new */
slot->allot = q->scaled_quantum;
}
}
+ sch->q.qlen -= dropped;
+ qdisc_tree_decrease_qlen(sch, dropped);
}
static void sfq_perturbation(unsigned long arg)
spin_lock(root_lock);
q->perturbation = net_random();
if (!q->filter_list && q->tail)
- sfq_rehash(q);
+ sfq_rehash(sch);
spin_unlock(root_lock);
if (q->perturb_period)
{
struct sfq_sched_data *q = qdisc_priv(sch);
struct tc_sfq_qopt *ctl = nla_data(opt);
+ struct tc_sfq_qopt_v1 *ctl_v1 = NULL;
unsigned int qlen;
if (opt->nla_len < nla_attr_size(sizeof(*ctl)))
return -EINVAL;
-
+ if (opt->nla_len >= nla_attr_size(sizeof(*ctl_v1)))
+ ctl_v1 = nla_data(opt);
if (ctl->divisor &&
(!is_power_of_2(ctl->divisor) || ctl->divisor > 65536))
return -EINVAL;
sch_tree_lock(sch);
- q->quantum = ctl->quantum ? : psched_mtu(qdisc_dev(sch));
- q->scaled_quantum = SFQ_ALLOT_SIZE(q->quantum);
+ if (ctl->quantum) {
+ q->quantum = ctl->quantum;
+ q->scaled_quantum = SFQ_ALLOT_SIZE(q->quantum);
+ }
q->perturb_period = ctl->perturb_period * HZ;
- if (ctl->limit)
- q->limit = min_t(u32, ctl->limit, SFQ_DEPTH - 1);
- if (ctl->divisor)
+ if (ctl->flows)
+ q->maxflows = min_t(u32, ctl->flows, SFQ_MAX_FLOWS);
+ if (ctl->divisor) {
q->divisor = ctl->divisor;
+ q->maxflows = min_t(u32, q->maxflows, q->divisor);
+ }
+ if (ctl_v1) {
+ if (ctl_v1->depth)
+ q->maxdepth = min_t(u32, ctl_v1->depth, SFQ_MAX_DEPTH);
+ q->headdrop = ctl_v1->headdrop;
+ }
+ if (ctl->limit) {
+ q->limit = min_t(u32, ctl->limit, q->maxdepth * q->maxflows);
+ q->maxflows = min_t(u32, q->maxflows, q->limit);
+ }
+
qlen = sch->q.qlen;
while (sch->q.qlen > q->limit)
sfq_drop(sch);
q->perturb_period = 0;
del_timer_sync(&q->perturb_timer);
sfq_free(q->ht);
+ sfq_free(q->slots);
}
static int sfq_init(struct Qdisc *sch, struct nlattr *opt)
q->perturb_timer.data = (unsigned long)sch;
init_timer_deferrable(&q->perturb_timer);
- for (i = 0; i < SFQ_DEPTH; i++) {
- q->dep[i].next = i + SFQ_SLOTS;
- q->dep[i].prev = i + SFQ_SLOTS;
+ for (i = 0; i < SFQ_MAX_DEPTH + 1; i++) {
+ q->dep[i].next = i + SFQ_MAX_FLOWS;
+ q->dep[i].prev = i + SFQ_MAX_FLOWS;
}
- q->limit = SFQ_DEPTH - 1;
+ q->limit = SFQ_MAX_DEPTH;
+ q->maxdepth = SFQ_MAX_DEPTH;
q->cur_depth = 0;
q->tail = NULL;
q->divisor = SFQ_DEFAULT_HASH_DIVISOR;
+ q->maxflows = SFQ_DEFAULT_FLOWS;
q->quantum = psched_mtu(qdisc_dev(sch));
q->scaled_quantum = SFQ_ALLOT_SIZE(q->quantum);
q->perturb_period = 0;
}
q->ht = sfq_alloc(sizeof(q->ht[0]) * q->divisor);
- if (!q->ht) {
+ q->slots = sfq_alloc(sizeof(q->slots[0]) * q->maxflows);
+ if (!q->ht || !q->slots) {
sfq_destroy(sch);
return -ENOMEM;
}
for (i = 0; i < q->divisor; i++)
q->ht[i] = SFQ_EMPTY_SLOT;
- for (i = 0; i < SFQ_SLOTS; i++) {
+ for (i = 0; i < q->maxflows; i++) {
slot_queue_init(&q->slots[i]);
sfq_link(q, i);
}
{
struct sfq_sched_data *q = qdisc_priv(sch);
unsigned char *b = skb_tail_pointer(skb);
- struct tc_sfq_qopt opt;
-
- opt.quantum = q->quantum;
- opt.perturb_period = q->perturb_period / HZ;
-
- opt.limit = q->limit;
- opt.divisor = q->divisor;
- opt.flows = q->limit;
+ struct tc_sfq_qopt_v1 opt;
+
+ memset(&opt, 0, sizeof(opt));
+ opt.v0.quantum = q->quantum;
+ opt.v0.perturb_period = q->perturb_period / HZ;
+ opt.v0.limit = q->limit;
+ opt.v0.divisor = q->divisor;
+ opt.v0.flows = q->maxflows;
+ opt.depth = q->maxdepth;
+ opt.headdrop = q->headdrop;
NLA_PUT(skb, TCA_OPTIONS, sizeof(opt), &opt);
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