2 * Copyright (c) 2010 Riccardo Panicucci, Luigi Rizzo, Universita` di Pisa
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28 * The API to write a packet scheduling algorithm for dummynet.
36 #define DN_MULTIQUEUE 0x01
38 * Descriptor for a scheduling algorithm.
39 * Contains all function pointers for a given scheduler
40 * This is typically created when a module is loaded, and stored
41 * in a global list of schedulers.
44 uint32_t type; /* the scheduler type */
45 const char *name; /* scheduler name */
46 uint32_t flags; /* DN_MULTIQUEUE if supports multiple queues */
49 * The following define the size of 3 optional data structures
50 * that may need to be allocated at runtime, and are appended
51 * to each of the base data structures: scheduler, sched.inst,
52 * and queue. We don't have a per-flowset structure.
54 /* + parameters attached to the template, e.g.
55 * default queue sizes, weights, quantum size, and so on;
59 /* + per-instance parameters, such as timestamps,
60 * containers for queues, etc;
64 size_t q_datalen; /* per-queue parameters (e.g. S,F) */
67 * Methods implemented by the scheduler:
68 * enqueue enqueue packet 'm' on scheduler 's', queue 'q'.
69 * q is NULL for !MULTIQUEUE.
70 * Return 0 on success, 1 on drop (packet consumed anyways).
71 * Note that q should be interpreted only as a hint
72 * on the flow that the mbuf belongs to: while a
73 * scheduler will normally enqueue m into q, it is ok
74 * to leave q alone and put the mbuf elsewhere.
75 * This function is called in two cases:
76 * - when a new packet arrives to the scheduler;
77 * - when a scheduler is reconfigured. In this case the
78 * call is issued by the new_queue callback, with a
79 * non empty queue (q) and m pointing to the first
80 * mbuf in the queue. For this reason, the function
81 * should internally check for (m != q->mq.head)
82 * before calling dn_enqueue().
84 * dequeue Called when scheduler instance 's' can
85 * dequeue a packet. Return NULL if none are available.
86 * XXX what about non work-conserving ?
88 * config called on 'sched X config ...', normally writes
89 * in the area of size sch_arg
91 * destroy called on 'sched delete', frees everything
92 * in sch_arg (other parts are handled by more specific
95 * new_sched called when a new instance is created, e.g.
96 * to create the local queue for !MULTIQUEUE, set V or
97 * copy parameters for WFQ, and so on.
99 * free_sched called when deleting an instance, cleans
100 * extra data in the per-instance area.
102 * new_fsk called when a flowset is linked to a scheduler,
103 * e.g. to validate parameters such as weights etc.
104 * free_fsk when a flowset is unlinked from a scheduler.
105 * (probably unnecessary)
107 * new_queue called to set the per-queue parameters,
108 * e.g. S and F, adjust sum of weights in the parent, etc.
110 * The new_queue callback is normally called from when
111 * creating a new queue. In some cases (such as a
112 * scheduler change or reconfiguration) it can be called
113 * with a non empty queue. In this case, the queue
114 * In case of non empty queue, the new_queue callback could
115 * need to call the enqueue function. In this case,
116 * the callback should eventually call enqueue() passing
117 * as m the first element in the queue.
119 * free_queue actions related to a queue removal, e.g. undo
120 * all the above. If the queue has data in it, also remove
121 * from the scheduler. This can e.g. happen during a reconfigure.
123 int (*enqueue)(struct dn_sch_inst *, struct dn_queue *,
125 struct mbuf * (*dequeue)(struct dn_sch_inst *);
127 int (*config)(struct dn_schk *);
128 int (*destroy)(struct dn_schk*);
129 int (*new_sched)(struct dn_sch_inst *);
130 int (*free_sched)(struct dn_sch_inst *);
131 int (*new_fsk)(struct dn_fsk *f);
132 int (*free_fsk)(struct dn_fsk *f);
133 int (*new_queue)(struct dn_queue *q);
134 int (*free_queue)(struct dn_queue *q);
136 /* run-time fields */
137 int ref_count; /* XXX number of instances in the system */
138 SLIST_ENTRY(dn_alg) next; /* Next scheduler in the list */
141 /* MSVC does not support initializers so we need this ugly macro */
149 * Additionally, dummynet exports some functions and macros
150 * to be used by schedulers:
153 void dn_free_pkts(struct mbuf *mnext);
154 int dn_enqueue(struct dn_queue *q, struct mbuf* m, int drop);
155 /* bound a variable between min and max */
156 int ipdn_bound_var(int *v, int dflt, int lo, int hi, const char *msg);
159 * Extract the head of a queue, update stats. Must be the very last
160 * thing done on a dequeue as the queue itself may go away.
162 static __inline struct mbuf*
163 dn_dequeue(struct dn_queue *q)
165 struct mbuf *m = q->mq.head;
168 q->mq.head = m->m_nextpkt;
170 /* Update stats for the queue */
172 q->ni.len_bytes -= m->m_pkthdr.len;
175 q->_si->ni.len_bytes -= m->m_pkthdr.len;
177 if (q->ni.length == 0) /* queue is now idle */
178 q->q_time = dn_cfg.curr_time;
182 int dn_sched_modevent(module_t mod, int cmd, void *arg);
184 #define DECLARE_DNSCHED_MODULE(name, dnsched) \
185 static moduledata_t name##_mod = { \
186 #name, dn_sched_modevent, dnsched \
188 DECLARE_MODULE(name, name##_mod, \
189 SI_SUB_PROTO_IFATTACHDOMAIN, SI_ORDER_ANY); \
190 MODULE_DEPEND(name, dummynet, 3, 3, 3);
191 #endif /* _DN_SCHED_H */