2 * Copyright (c) 2010 Riccardo Panicucci, Universita` di Pisa
3 * Copyright (c) 2000-2002 Luigi Rizzo, Universita` di Pisa
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
9 * 1. Redistributions of source code must retain the above copyright
10 * notice, this list of conditions and the following disclaimer.
11 * 2. Redistributions in binary form must reproduce the above copyright
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13 * documentation and/or other materials provided with the distribution.
15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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18 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
19 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
20 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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24 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
29 * $Id: dn_sched_wf2q.c 6338 2010-05-26 15:06:34Z svn_panicucci $
33 #include <sys/malloc.h>
34 #include <sys/socket.h>
35 #include <sys/socketvar.h>
36 #include <sys/kernel.h>
38 #include <sys/module.h>
39 #include <net/if.h> /* IFNAMSIZ */
40 #include <netinet/in.h>
41 #include <netinet/ip_var.h> /* ipfw_rule_ref */
42 #include <netinet/ip_fw.h> /* flow_id */
43 #include <netinet/ip_dummynet.h>
44 #include <netinet/ipfw/dn_heap.h>
45 #include <netinet/ipfw/ip_dn_private.h>
46 #include <netinet/ipfw/dn_sched.h>
52 #define MAX64(x,y) (( (int64_t) ( (y)-(x) )) > 0 ) ? (y) : (x)
56 * timestamps are computed on 64 bit using fixed point arithmetic.
57 * LMAX_BITS, WMAX_BITS are the max number of bits for the packet len
58 * and sum of weights, respectively. FRAC_BITS is the number of
59 * fractional bits. We want FRAC_BITS >> WMAX_BITS to avoid too large
60 * errors when computing the inverse, FRAC_BITS < 32 so we can do 1/w
61 * using an unsigned 32-bit division, and to avoid wraparounds we need
62 * LMAX_BITS + WMAX_BITS + FRAC_BITS << 64
64 * FRAC_BITS = 26, LMAX_BITS=14, WMAX_BITS = 19
67 #define FRAC_BITS 28 /* shift for fixed point arithmetic */
68 #define ONE_FP (1UL << FRAC_BITS)
72 * Private information for the scheduler instance:
73 * sch_heap (key is Finish time) returns the next queue to serve
74 * ne_heap (key is Start time) stores not-eligible queues
75 * idle_heap (key=start/finish time) stores idle flows. It must
76 * support extract-from-middle.
77 * A flow is only in 1 of the three heaps.
78 * XXX todo: use a more efficient data structure, e.g. a tree sorted
79 * by F with min_subtree(S) in each node
82 struct dn_heap sch_heap; /* top extract - key Finish time */
83 struct dn_heap ne_heap; /* top extract - key Start time */
84 struct dn_heap idle_heap; /* random extract - key Start=Finish time */
85 uint64_t V; /* virtual time */
86 uint32_t inv_wsum; /* inverse of sum of weights */
87 uint32_t wsum; /* sum of weights */
92 uint64_t S, F; /* start time, finish time */
93 uint32_t inv_w; /* ONE_FP / weight */
94 int32_t heap_pos; /* position (index) of struct in heap */
98 * This file implements a WF2Q+ scheduler as it has been in dummynet
100 * The scheduler supports per-flow queues and has O(log N) complexity.
102 * WF2Q+ needs to drain entries from the idle heap so that we
103 * can keep the sum of weights up to date. We can do it whenever
104 * we get a chance, or periodically, or following some other
105 * strategy. The function idle_check() drains at most N elements
106 * from the idle heap.
109 idle_check(struct wf2qp_si *si, int n, int force)
111 struct dn_heap *h = &si->idle_heap;
112 while (n-- > 0 && h->elements > 0 &&
113 (force || DN_KEY_LT(HEAP_TOP(h)->key, si->V))) {
114 struct dn_queue *q = HEAP_TOP(h)->object;
115 struct wf2qp_queue *alg_fq = (struct wf2qp_queue *)q;
117 heap_extract(h, NULL);
118 /* XXX to let the flowset delete the queue we should
119 * mark it as 'unused' by the scheduler.
121 alg_fq->S = alg_fq->F + 1; /* Mark timestamp as invalid. */
122 si->wsum -= q->fs->fs.par[0]; /* adjust sum of weights */
124 si->inv_wsum = ONE_FP/si->wsum;
129 wf2qp_enqueue(struct dn_sch_inst *_si, struct dn_queue *q, struct mbuf *m)
131 struct dn_fsk *fs = q->fs;
132 struct wf2qp_si *si = (struct wf2qp_si *)(_si + 1);
133 struct wf2qp_queue *alg_fq;
134 uint64_t len = m->m_pkthdr.len;
136 if (m != q->mq.head) {
137 if (dn_enqueue(q, m, 0)) /* packet was dropped */
139 if (m != q->mq.head) /* queue was already busy */
143 /* If reach this point, queue q was idle */
144 alg_fq = (struct wf2qp_queue *)q;
146 if (DN_KEY_LT(alg_fq->F, alg_fq->S)) {
147 /* F<S means timestamps are invalid ->brand new queue. */
148 alg_fq->S = si->V; /* init start time */
149 si->wsum += fs->fs.par[0]; /* add weight of new queue. */
150 si->inv_wsum = ONE_FP/si->wsum;
151 } else { /* if it was idle then it was in the idle heap */
152 heap_extract(&si->idle_heap, q);
153 alg_fq->S = MAX64(alg_fq->F, si->V); /* compute new S */
155 alg_fq->F = alg_fq->S + len * alg_fq->inv_w;
157 /* if nothing is backlogged, make sure this flow is eligible */
158 if (si->ne_heap.elements == 0 && si->sch_heap.elements == 0)
159 si->V = MAX64(alg_fq->S, si->V);
162 * Look at eligibility. A flow is not eligibile if S>V (when
163 * this happens, it means that there is some other flow already
164 * scheduled for the same pipe, so the sch_heap cannot be
165 * empty). If the flow is not eligible we just store it in the
166 * ne_heap. Otherwise, we store in the sch_heap.
167 * Note that for all flows in sch_heap (SCH), S_i <= V,
168 * and for all flows in ne_heap (NEH), S_i > V.
169 * So when we need to compute max(V, min(S_i)) forall i in
170 * SCH+NEH, we only need to look into NEH.
172 if (DN_KEY_LT(si->V, alg_fq->S)) {
173 /* S>V means flow Not eligible. */
174 if (si->sch_heap.elements == 0)
175 D("++ ouch! not eligible but empty scheduler!");
176 heap_insert(&si->ne_heap, alg_fq->S, q);
178 heap_insert(&si->sch_heap, alg_fq->F, q);
183 /* XXX invariant: sch > 0 || V >= min(S in neh) */
185 wf2qp_dequeue(struct dn_sch_inst *_si)
187 /* Access scheduler instance private data */
188 struct wf2qp_si *si = (struct wf2qp_si *)(_si + 1);
191 struct dn_heap *sch = &si->sch_heap;
192 struct dn_heap *neh = &si->ne_heap;
193 struct wf2qp_queue *alg_fq;
195 if (sch->elements == 0 && neh->elements == 0) {
196 /* we have nothing to do. We could kill the idle heap
197 * altogether and reset V
199 idle_check(si, 0x7fffffff, 1);
201 si->wsum = 0; /* should be set already */
202 return NULL; /* quick return if nothing to do */
204 idle_check(si, 1, 0); /* drain something from the idle heap */
206 /* make sure at least one element is eligible, bumping V
207 * and moving entries that have become eligible.
208 * We need to repeat the first part twice, before and
209 * after extracting the candidate, or enqueue() will
210 * find the data structure in a wrong state.
215 * Compute V = max(V, min(S_i)). Remember that all elements
216 * in sch have by definition S_i <= V so if sch is not empty,
217 * V is surely the max and we must not update it. Conversely,
218 * if sch is empty we only need to look at neh.
219 * We don't need to move the queues, as it will be done at the
222 if (sch->elements == 0 && neh->elements > 0) {
223 si->V = MAX64(si->V, HEAP_TOP(neh)->key);
225 while (neh->elements > 0 &&
226 DN_KEY_LEQ(HEAP_TOP(neh)->key, si->V)) {
227 q = HEAP_TOP(neh)->object;
228 alg_fq = (struct wf2qp_queue *)q;
229 heap_extract(neh, NULL);
230 heap_insert(sch, alg_fq->F, q);
232 if (m) /* pkt found in previous iteration */
234 /* ok we have at least one eligible pkt */
235 q = HEAP_TOP(sch)->object;
236 alg_fq = (struct wf2qp_queue *)q;
238 heap_extract(sch, NULL); /* Remove queue from heap. */
239 si->V += (uint64_t)(m->m_pkthdr.len) * si->inv_wsum;
240 alg_fq->S = alg_fq->F; /* Update start time. */
241 if (q->mq.head == 0) { /* not backlogged any more. */
242 heap_insert(&si->idle_heap, alg_fq->F, q);
243 } else { /* Still backlogged. */
244 /* Update F, store in neh or sch */
245 uint64_t len = q->mq.head->m_pkthdr.len;
246 alg_fq->F += len * alg_fq->inv_w;
247 if (DN_KEY_LEQ(alg_fq->S, si->V)) {
248 heap_insert(sch, alg_fq->F, q);
250 heap_insert(neh, alg_fq->S, q);
258 wf2qp_new_sched(struct dn_sch_inst *_si)
260 struct wf2qp_si *si = (struct wf2qp_si *)(_si + 1);
261 int ofs = offsetof(struct wf2qp_queue, heap_pos);
263 /* all heaps support extract from middle */
264 if (heap_init(&si->idle_heap, 16, ofs) ||
265 heap_init(&si->sch_heap, 16, ofs) ||
266 heap_init(&si->ne_heap, 16, ofs)) {
267 heap_free(&si->ne_heap);
268 heap_free(&si->sch_heap);
269 heap_free(&si->idle_heap);
276 wf2qp_free_sched(struct dn_sch_inst *_si)
278 struct wf2qp_si *si = (struct wf2qp_si *)(_si + 1);
280 heap_free(&si->sch_heap);
281 heap_free(&si->ne_heap);
282 heap_free(&si->idle_heap);
288 wf2qp_new_fsk(struct dn_fsk *fs)
290 ipdn_bound_var(&fs->fs.par[0], 1,
291 1, 100, "WF2Q+ weight");
296 wf2qp_new_queue(struct dn_queue *_q)
298 struct wf2qp_queue *q = (struct wf2qp_queue *)_q;
300 _q->ni.oid.subtype = DN_SCHED_WF2QP;
301 q->F = 0; /* not strictly necessary */
302 q->S = q->F + 1; /* mark timestamp as invalid. */
303 q->inv_w = ONE_FP / _q->fs->fs.par[0];
304 if (_q->mq.head != NULL) {
305 wf2qp_enqueue(_q->_si, _q, _q->mq.head);
311 * Called when the infrastructure removes a queue (e.g. flowset
312 * is reconfigured). Nothing to do if we did not 'own' the queue,
313 * otherwise remove it from the right heap and adjust the sum
317 wf2qp_free_queue(struct dn_queue *q, int safe)
319 struct wf2qp_queue *alg_fq = (struct wf2qp_queue *)q;
320 struct wf2qp_si *si = (struct wf2qp_si *)(q->_si + 1);
322 if (alg_fq->S >= alg_fq->F + 1)
323 return 0; /* nothing to do, not in any heap */
325 /* queue is in a scheduler heap */
326 if (safe) /* do not delete in safe mode */
329 si->wsum -= q->fs->fs.par[0];
331 si->inv_wsum = ONE_FP/si->wsum;
333 /* extract from the heap. XXX TODO we may need to adjust V
334 * to make sure the invariants hold.
336 if (q->mq.head == NULL) {
337 heap_extract(&si->idle_heap, q);
338 } else if (DN_KEY_LT(si->V, alg_fq->S)) {
339 heap_extract(&si->ne_heap, q);
341 heap_extract(&si->sch_heap, q);
347 * WF2Q+ scheduler descriptor
348 * contains the type of the scheduler, the name, the size of the
349 * structures and function pointers.
351 static struct dn_alg wf2qp_desc = {
352 _SI( .type = ) DN_SCHED_WF2QP,
353 _SI( .name = ) "WF2Q+",
354 _SI( .flags = ) DN_MULTIQUEUE,
356 /* we need extra space in the si and the queue */
357 _SI( .schk_datalen = ) 0,
358 _SI( .si_datalen = ) sizeof(struct wf2qp_si),
359 _SI( .q_datalen = ) sizeof(struct wf2qp_queue) -
360 sizeof(struct dn_queue),
362 _SI( .enqueue = ) wf2qp_enqueue,
363 _SI( .dequeue = ) wf2qp_dequeue,
365 _SI( .config = ) NULL,
366 _SI( .destroy = ) NULL,
367 _SI( .new_sched = ) wf2qp_new_sched,
368 _SI( .free_sched = ) wf2qp_free_sched,
370 _SI( .new_fsk = ) wf2qp_new_fsk,
371 _SI( .free_fsk = ) NULL,
373 _SI( .new_queue = ) wf2qp_new_queue,
374 _SI( .free_queue = ) wf2qp_free_queue,
378 DECLARE_DNSCHED_MODULE(dn_wf2qp, &wf2qp_desc);