xref: /freebsd/sys/netpfil/ipfw/dn_sched_fq_pie.c (revision 3c5ba95ad12285ad37c182a4bfc1b240ec6d18a7)
1 /*
2  * FQ_PIE - The FlowQueue-PIE scheduler/AQM
3  *
4  * $FreeBSD$
5  *
6  * Copyright (C) 2016 Centre for Advanced Internet Architectures,
7  *  Swinburne University of Technology, Melbourne, Australia.
8  * Portions of this code were made possible in part by a gift from
9  *  The Comcast Innovation Fund.
10  * Implemented by Rasool Al-Saadi <ralsaadi@swin.edu.au>
11  *
12  * Redistribution and use in source and binary forms, with or without
13  * modification, are permitted provided that the following conditions
14  * are met:
15  * 1. Redistributions of source code must retain the above copyright
16  *    notice, this list of conditions and the following disclaimer.
17  * 2. Redistributions in binary form must reproduce the above copyright
18  *    notice, this list of conditions and the following disclaimer in the
19  *    documentation and/or other materials provided with the distribution.
20  *
21  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
22  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
23  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
24  * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
25  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
26  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
27  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
28  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
29  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
30  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
31  * SUCH DAMAGE.
32  */
33 
34 /* Important note:
35  * As there is no an office document for FQ-PIE specification, we used
36  * FQ-CoDel algorithm with some modifications to implement FQ-PIE.
37  * This FQ-PIE implementation is a beta version and have not been tested
38  * extensively. Our FQ-PIE uses stand-alone PIE AQM per sub-queue. By
39  * default, timestamp is used to calculate queue delay instead of departure
40  * rate estimation method. Although departure rate estimation is available
41  * as testing option, the results could be incorrect. Moreover, turning PIE on
42  * and off option is available but it does not work properly in this version.
43  */
44 
45 
46 #ifdef _KERNEL
47 #include <sys/malloc.h>
48 #include <sys/socket.h>
49 #include <sys/kernel.h>
50 #include <sys/mbuf.h>
51 #include <sys/lock.h>
52 #include <sys/module.h>
53 #include <sys/mutex.h>
54 #include <net/if.h>	/* IFNAMSIZ */
55 #include <netinet/in.h>
56 #include <netinet/ip_var.h>		/* ipfw_rule_ref */
57 #include <netinet/ip_fw.h>	/* flow_id */
58 #include <netinet/ip_dummynet.h>
59 
60 #include <sys/proc.h>
61 #include <sys/rwlock.h>
62 
63 #include <netpfil/ipfw/ip_fw_private.h>
64 #include <sys/sysctl.h>
65 #include <netinet/ip.h>
66 #include <netinet/ip6.h>
67 #include <netinet/ip_icmp.h>
68 #include <netinet/tcp.h>
69 #include <netinet/udp.h>
70 #include <sys/queue.h>
71 #include <sys/hash.h>
72 
73 #include <netpfil/ipfw/dn_heap.h>
74 #include <netpfil/ipfw/ip_dn_private.h>
75 
76 #include <netpfil/ipfw/dn_aqm.h>
77 #include <netpfil/ipfw/dn_aqm_pie.h>
78 #include <netpfil/ipfw/dn_sched.h>
79 
80 #else
81 #include <dn_test.h>
82 #endif
83 
84 #define DN_SCHED_FQ_PIE 7
85 
86 /* list of queues */
87 STAILQ_HEAD(fq_pie_list, fq_pie_flow) ;
88 
89 /* FQ_PIE parameters including PIE */
90 struct dn_sch_fq_pie_parms {
91 	struct dn_aqm_pie_parms	pcfg;	/* PIE configuration Parameters */
92 	/* FQ_PIE Parameters */
93 	uint32_t flows_cnt;	/* number of flows */
94 	uint32_t limit;	/* hard limit of FQ_PIE queue size*/
95 	uint32_t quantum;
96 };
97 
98 /* flow (sub-queue) stats */
99 struct flow_stats {
100 	uint64_t tot_pkts;	/* statistics counters  */
101 	uint64_t tot_bytes;
102 	uint32_t length;		/* Queue length, in packets */
103 	uint32_t len_bytes;	/* Queue length, in bytes */
104 	uint32_t drops;
105 };
106 
107 /* A flow of packets (sub-queue)*/
108 struct fq_pie_flow {
109 	struct mq	mq;	/* list of packets */
110 	struct flow_stats stats;	/* statistics */
111 	int deficit;
112 	int active;		/* 1: flow is active (in a list) */
113 	struct pie_status pst;	/* pie status variables */
114 	struct fq_pie_si_extra *psi_extra;
115 	STAILQ_ENTRY(fq_pie_flow) flowchain;
116 };
117 
118 /* extra fq_pie scheduler configurations */
119 struct fq_pie_schk {
120 	struct dn_sch_fq_pie_parms cfg;
121 };
122 
123 
124 /* fq_pie scheduler instance extra state vars.
125  * The purpose of separation this structure is to preserve number of active
126  * sub-queues and the flows array pointer even after the scheduler instance
127  * is destroyed.
128  * Preserving these varaiables allows freeing the allocated memory by
129  * fqpie_callout_cleanup() independently from fq_pie_free_sched().
130  */
131 struct fq_pie_si_extra {
132 	uint32_t nr_active_q;	/* number of active queues */
133 	struct fq_pie_flow *flows;	/* array of flows (queues) */
134 	};
135 
136 /* fq_pie scheduler instance */
137 struct fq_pie_si {
138 	struct dn_sch_inst _si;	/* standard scheduler instance. SHOULD BE FIRST */
139 	struct dn_queue main_q; /* main queue is after si directly */
140 	uint32_t perturbation; 	/* random value */
141 	struct fq_pie_list newflows;	/* list of new queues */
142 	struct fq_pie_list oldflows;	/* list of old queues */
143 	struct fq_pie_si_extra *si_extra; /* extra state vars*/
144 };
145 
146 
147 static struct dn_alg fq_pie_desc;
148 
149 /*  Default FQ-PIE parameters including PIE */
150 /*  PIE defaults
151  * target=15ms, max_burst=150ms, max_ecnth=0.1,
152  * alpha=0.125, beta=1.25, tupdate=15ms
153  * FQ-
154  * flows=1024, limit=10240, quantum =1514
155  */
156 struct dn_sch_fq_pie_parms
157  fq_pie_sysctl = {{15000 * AQM_TIME_1US, 15000 * AQM_TIME_1US,
158 	150000 * AQM_TIME_1US, PIE_SCALE * 0.1, PIE_SCALE * 0.125,
159 	PIE_SCALE * 1.25,	PIE_CAPDROP_ENABLED | PIE_DERAND_ENABLED},
160 	1024, 10240, 1514};
161 
162 static int
163 fqpie_sysctl_alpha_beta_handler(SYSCTL_HANDLER_ARGS)
164 {
165 	int error;
166 	long  value;
167 
168 	if (!strcmp(oidp->oid_name,"alpha"))
169 		value = fq_pie_sysctl.pcfg.alpha;
170 	else
171 		value = fq_pie_sysctl.pcfg.beta;
172 
173 	value = value * 1000 / PIE_SCALE;
174 	error = sysctl_handle_long(oidp, &value, 0, req);
175 	if (error != 0 || req->newptr == NULL)
176 		return (error);
177 	if (value < 1 || value > 7 * PIE_SCALE)
178 		return (EINVAL);
179 	value = (value * PIE_SCALE) / 1000;
180 	if (!strcmp(oidp->oid_name,"alpha"))
181 			fq_pie_sysctl.pcfg.alpha = value;
182 	else
183 		fq_pie_sysctl.pcfg.beta = value;
184 	return (0);
185 }
186 
187 static int
188 fqpie_sysctl_target_tupdate_maxb_handler(SYSCTL_HANDLER_ARGS)
189 {
190 	int error;
191 	long  value;
192 
193 	if (!strcmp(oidp->oid_name,"target"))
194 		value = fq_pie_sysctl.pcfg.qdelay_ref;
195 	else if (!strcmp(oidp->oid_name,"tupdate"))
196 		value = fq_pie_sysctl.pcfg.tupdate;
197 	else
198 		value = fq_pie_sysctl.pcfg.max_burst;
199 
200 	value = value / AQM_TIME_1US;
201 	error = sysctl_handle_long(oidp, &value, 0, req);
202 	if (error != 0 || req->newptr == NULL)
203 		return (error);
204 	if (value < 1 || value > 10 * AQM_TIME_1S)
205 		return (EINVAL);
206 	value = value * AQM_TIME_1US;
207 
208 	if (!strcmp(oidp->oid_name,"target"))
209 		fq_pie_sysctl.pcfg.qdelay_ref  = value;
210 	else if (!strcmp(oidp->oid_name,"tupdate"))
211 		fq_pie_sysctl.pcfg.tupdate  = value;
212 	else
213 		fq_pie_sysctl.pcfg.max_burst = value;
214 	return (0);
215 }
216 
217 static int
218 fqpie_sysctl_max_ecnth_handler(SYSCTL_HANDLER_ARGS)
219 {
220 	int error;
221 	long  value;
222 
223 	value = fq_pie_sysctl.pcfg.max_ecnth;
224 	value = value * 1000 / PIE_SCALE;
225 	error = sysctl_handle_long(oidp, &value, 0, req);
226 	if (error != 0 || req->newptr == NULL)
227 		return (error);
228 	if (value < 1 || value > PIE_SCALE)
229 		return (EINVAL);
230 	value = (value * PIE_SCALE) / 1000;
231 	fq_pie_sysctl.pcfg.max_ecnth = value;
232 	return (0);
233 }
234 
235 /* define FQ- PIE sysctl variables */
236 SYSBEGIN(f4)
237 SYSCTL_DECL(_net_inet);
238 SYSCTL_DECL(_net_inet_ip);
239 SYSCTL_DECL(_net_inet_ip_dummynet);
240 static SYSCTL_NODE(_net_inet_ip_dummynet, OID_AUTO, fqpie,
241 	CTLFLAG_RW, 0, "FQ_PIE");
242 
243 #ifdef SYSCTL_NODE
244 
245 SYSCTL_PROC(_net_inet_ip_dummynet_fqpie, OID_AUTO, target,
246 	CTLTYPE_LONG | CTLFLAG_RW, NULL, 0,
247 	fqpie_sysctl_target_tupdate_maxb_handler, "L",
248 	"queue target in microsecond");
249 
250 SYSCTL_PROC(_net_inet_ip_dummynet_fqpie, OID_AUTO, tupdate,
251 	CTLTYPE_LONG | CTLFLAG_RW, NULL, 0,
252 	fqpie_sysctl_target_tupdate_maxb_handler, "L",
253 	"the frequency of drop probability calculation in microsecond");
254 
255 SYSCTL_PROC(_net_inet_ip_dummynet_fqpie, OID_AUTO, max_burst,
256 	CTLTYPE_LONG | CTLFLAG_RW, NULL, 0,
257 	fqpie_sysctl_target_tupdate_maxb_handler, "L",
258 	"Burst allowance interval in microsecond");
259 
260 SYSCTL_PROC(_net_inet_ip_dummynet_fqpie, OID_AUTO, max_ecnth,
261 	CTLTYPE_LONG | CTLFLAG_RW, NULL, 0,
262 	fqpie_sysctl_max_ecnth_handler, "L",
263 	"ECN safeguard threshold scaled by 1000");
264 
265 SYSCTL_PROC(_net_inet_ip_dummynet_fqpie, OID_AUTO, alpha,
266 	CTLTYPE_LONG | CTLFLAG_RW, NULL, 0,
267 	fqpie_sysctl_alpha_beta_handler, "L", "PIE alpha scaled by 1000");
268 
269 SYSCTL_PROC(_net_inet_ip_dummynet_fqpie, OID_AUTO, beta,
270 	CTLTYPE_LONG | CTLFLAG_RW, NULL, 0,
271 	fqpie_sysctl_alpha_beta_handler, "L", "beta scaled by 1000");
272 
273 SYSCTL_UINT(_net_inet_ip_dummynet_fqpie, OID_AUTO, quantum,
274 	CTLFLAG_RW, &fq_pie_sysctl.quantum, 1514, "quantum for FQ_PIE");
275 SYSCTL_UINT(_net_inet_ip_dummynet_fqpie, OID_AUTO, flows,
276 	CTLFLAG_RW, &fq_pie_sysctl.flows_cnt, 1024, "Number of queues for FQ_PIE");
277 SYSCTL_UINT(_net_inet_ip_dummynet_fqpie, OID_AUTO, limit,
278 	CTLFLAG_RW, &fq_pie_sysctl.limit, 10240, "limit for FQ_PIE");
279 #endif
280 
281 /* Helper function to update queue&main-queue and scheduler statistics.
282  * negative len & drop -> drop
283  * negative len -> dequeue
284  * positive len -> enqueue
285  * positive len + drop -> drop during enqueue
286  */
287 __inline static void
288 fq_update_stats(struct fq_pie_flow *q, struct fq_pie_si *si, int len,
289 	int drop)
290 {
291 	int inc = 0;
292 
293 	if (len < 0)
294 		inc = -1;
295 	else if (len > 0)
296 		inc = 1;
297 
298 	if (drop) {
299 		si->main_q.ni.drops ++;
300 		q->stats.drops ++;
301 		si->_si.ni.drops ++;
302 		io_pkt_drop ++;
303 	}
304 
305 	if (!drop || (drop && len < 0)) {
306 		/* Update stats for the main queue */
307 		si->main_q.ni.length += inc;
308 		si->main_q.ni.len_bytes += len;
309 
310 		/*update sub-queue stats */
311 		q->stats.length += inc;
312 		q->stats.len_bytes += len;
313 
314 		/*update scheduler instance stats */
315 		si->_si.ni.length += inc;
316 		si->_si.ni.len_bytes += len;
317 	}
318 
319 	if (inc > 0) {
320 		si->main_q.ni.tot_bytes += len;
321 		si->main_q.ni.tot_pkts ++;
322 
323 		q->stats.tot_bytes +=len;
324 		q->stats.tot_pkts++;
325 
326 		si->_si.ni.tot_bytes +=len;
327 		si->_si.ni.tot_pkts ++;
328 	}
329 
330 }
331 
332 /*
333  * Extract a packet from the head of sub-queue 'q'
334  * Return a packet or NULL if the queue is empty.
335  * If getts is set, also extract packet's timestamp from mtag.
336  */
337 __inline static struct mbuf *
338 fq_pie_extract_head(struct fq_pie_flow *q, aqm_time_t *pkt_ts,
339 	struct fq_pie_si *si, int getts)
340 {
341 	struct mbuf *m = q->mq.head;
342 
343 	if (m == NULL)
344 		return m;
345 	q->mq.head = m->m_nextpkt;
346 
347 	fq_update_stats(q, si, -m->m_pkthdr.len, 0);
348 
349 	if (si->main_q.ni.length == 0) /* queue is now idle */
350 			si->main_q.q_time = dn_cfg.curr_time;
351 
352 	if (getts) {
353 		/* extract packet timestamp*/
354 		struct m_tag *mtag;
355 		mtag = m_tag_locate(m, MTAG_ABI_COMPAT, DN_AQM_MTAG_TS, NULL);
356 		if (mtag == NULL){
357 			D("PIE timestamp mtag not found!");
358 			*pkt_ts = 0;
359 		} else {
360 			*pkt_ts = *(aqm_time_t *)(mtag + 1);
361 			m_tag_delete(m,mtag);
362 		}
363 	}
364 	return m;
365 }
366 
367 /*
368  * Callout function for drop probability calculation
369  * This function is called over tupdate ms and takes pointer of FQ-PIE
370  * flow as an argument
371   */
372 static void
373 fq_calculate_drop_prob(void *x)
374 {
375 	struct fq_pie_flow *q = (struct fq_pie_flow *) x;
376 	struct pie_status *pst = &q->pst;
377 	struct dn_aqm_pie_parms *pprms;
378 	int64_t p, prob, oldprob;
379 	aqm_time_t now;
380 	int p_isneg;
381 
382 	now = AQM_UNOW;
383 	pprms = pst->parms;
384 	prob = pst->drop_prob;
385 
386 	/* calculate current qdelay using DRE method.
387 	 * If TS is used and no data in the queue, reset current_qdelay
388 	 * as it stays at last value during dequeue process.
389 	*/
390 	if (pprms->flags & PIE_DEPRATEEST_ENABLED)
391 		pst->current_qdelay = ((uint64_t)q->stats.len_bytes  * pst->avg_dq_time)
392 			>> PIE_DQ_THRESHOLD_BITS;
393 	else
394 		if (!q->stats.len_bytes)
395 			pst->current_qdelay = 0;
396 
397 	/* calculate drop probability */
398 	p = (int64_t)pprms->alpha *
399 		((int64_t)pst->current_qdelay - (int64_t)pprms->qdelay_ref);
400 	p +=(int64_t) pprms->beta *
401 		((int64_t)pst->current_qdelay - (int64_t)pst->qdelay_old);
402 
403 	/* take absolute value so right shift result is well defined */
404 	p_isneg = p < 0;
405 	if (p_isneg) {
406 		p = -p;
407 	}
408 
409 	/* We PIE_MAX_PROB shift by 12-bits to increase the division precision  */
410 	p *= (PIE_MAX_PROB << 12) / AQM_TIME_1S;
411 
412 	/* auto-tune drop probability */
413 	if (prob < (PIE_MAX_PROB / 1000000)) /* 0.000001 */
414 		p >>= 11 + PIE_FIX_POINT_BITS + 12;
415 	else if (prob < (PIE_MAX_PROB / 100000)) /* 0.00001 */
416 		p >>= 9 + PIE_FIX_POINT_BITS + 12;
417 	else if (prob < (PIE_MAX_PROB / 10000)) /* 0.0001 */
418 		p >>= 7 + PIE_FIX_POINT_BITS + 12;
419 	else if (prob < (PIE_MAX_PROB / 1000)) /* 0.001 */
420 		p >>= 5 + PIE_FIX_POINT_BITS + 12;
421 	else if (prob < (PIE_MAX_PROB / 100)) /* 0.01 */
422 		p >>= 3 + PIE_FIX_POINT_BITS + 12;
423 	else if (prob < (PIE_MAX_PROB / 10)) /* 0.1 */
424 		p >>= 1 + PIE_FIX_POINT_BITS + 12;
425 	else
426 		p >>= PIE_FIX_POINT_BITS + 12;
427 
428 	oldprob = prob;
429 
430 	if (p_isneg) {
431 		prob = prob - p;
432 
433 		/* check for multiplication underflow */
434 		if (prob > oldprob) {
435 			prob= 0;
436 			D("underflow");
437 		}
438 	} else {
439 		/* Cap Drop adjustment */
440 		if ((pprms->flags & PIE_CAPDROP_ENABLED) &&
441 		    prob >= PIE_MAX_PROB / 10 &&
442 		    p > PIE_MAX_PROB / 50 ) {
443 			p = PIE_MAX_PROB / 50;
444 		}
445 
446 		prob = prob + p;
447 
448 		/* check for multiplication overflow */
449 		if (prob<oldprob) {
450 			D("overflow");
451 			prob= PIE_MAX_PROB;
452 		}
453 	}
454 
455 	/*
456 	 * decay the drop probability exponentially
457 	 * and restrict it to range 0 to PIE_MAX_PROB
458 	 */
459 	if (prob < 0) {
460 		prob = 0;
461 	} else {
462 		if (pst->current_qdelay == 0 && pst->qdelay_old == 0) {
463 			/* 0.98 ~= 1- 1/64 */
464 			prob = prob - (prob >> 6);
465 		}
466 
467 		if (prob > PIE_MAX_PROB) {
468 			prob = PIE_MAX_PROB;
469 		}
470 	}
471 
472 	pst->drop_prob = prob;
473 
474 	/* store current delay value */
475 	pst->qdelay_old = pst->current_qdelay;
476 
477 	/* update burst allowance */
478 	if ((pst->sflags & PIE_ACTIVE) && pst->burst_allowance) {
479 		if (pst->burst_allowance > pprms->tupdate)
480 			pst->burst_allowance -= pprms->tupdate;
481 		else
482 			pst->burst_allowance = 0;
483 	}
484 
485 	if (pst->sflags & PIE_ACTIVE)
486 	callout_reset_sbt(&pst->aqm_pie_callout,
487 		(uint64_t)pprms->tupdate * SBT_1US,
488 		0, fq_calculate_drop_prob, q, 0);
489 
490 	mtx_unlock(&pst->lock_mtx);
491 }
492 
493 /*
494  * Reset PIE variables & activate the queue
495  */
496 __inline static void
497 fq_activate_pie(struct fq_pie_flow *q)
498 {
499 	struct pie_status *pst = &q->pst;
500 	struct dn_aqm_pie_parms *pprms;
501 
502 	mtx_lock(&pst->lock_mtx);
503 	pprms = pst->parms;
504 
505 	pprms = pst->parms;
506 	pst->drop_prob = 0;
507 	pst->qdelay_old = 0;
508 	pst->burst_allowance = pprms->max_burst;
509 	pst->accu_prob = 0;
510 	pst->dq_count = 0;
511 	pst->avg_dq_time = 0;
512 	pst->sflags = PIE_INMEASUREMENT | PIE_ACTIVE;
513 	pst->measurement_start = AQM_UNOW;
514 
515 	callout_reset_sbt(&pst->aqm_pie_callout,
516 		(uint64_t)pprms->tupdate * SBT_1US,
517 		0, fq_calculate_drop_prob, q, 0);
518 
519 	mtx_unlock(&pst->lock_mtx);
520 }
521 
522 
523  /*
524   * Deactivate PIE and stop probe update callout
525   */
526 __inline static void
527 fq_deactivate_pie(struct pie_status *pst)
528 {
529 	mtx_lock(&pst->lock_mtx);
530 	pst->sflags &= ~(PIE_ACTIVE | PIE_INMEASUREMENT);
531 	callout_stop(&pst->aqm_pie_callout);
532 	//D("PIE Deactivated");
533 	mtx_unlock(&pst->lock_mtx);
534 }
535 
536  /*
537   * Initialize PIE for sub-queue 'q'
538   */
539 static int
540 pie_init(struct fq_pie_flow *q, struct fq_pie_schk *fqpie_schk)
541 {
542 	struct pie_status *pst=&q->pst;
543 	struct dn_aqm_pie_parms *pprms = pst->parms;
544 
545 	int err = 0;
546 	if (!pprms){
547 		D("AQM_PIE is not configured");
548 		err = EINVAL;
549 	} else {
550 		q->psi_extra->nr_active_q++;
551 
552 		/* For speed optimization, we caculate 1/3 queue size once here */
553 		// XXX limit divided by number of queues divided by 3 ???
554 		pst->one_third_q_size = (fqpie_schk->cfg.limit /
555 			fqpie_schk->cfg.flows_cnt) / 3;
556 
557 		mtx_init(&pst->lock_mtx, "mtx_pie", NULL, MTX_DEF);
558 		callout_init_mtx(&pst->aqm_pie_callout, &pst->lock_mtx,
559 			CALLOUT_RETURNUNLOCKED);
560 	}
561 
562 	return err;
563 }
564 
565 /*
566  * callout function to destroy PIE lock, and free fq_pie flows and fq_pie si
567  * extra memory when number of active sub-queues reaches zero.
568  * 'x' is a fq_pie_flow to be destroyed
569  */
570 static void
571 fqpie_callout_cleanup(void *x)
572 {
573 	struct fq_pie_flow *q = x;
574 	struct pie_status *pst = &q->pst;
575 	struct fq_pie_si_extra *psi_extra;
576 
577 	mtx_unlock(&pst->lock_mtx);
578 	mtx_destroy(&pst->lock_mtx);
579 	psi_extra = q->psi_extra;
580 
581 	DN_BH_WLOCK();
582 	psi_extra->nr_active_q--;
583 
584 	/* when all sub-queues are destroyed, free flows fq_pie extra vars memory */
585 	if (!psi_extra->nr_active_q) {
586 		free(psi_extra->flows, M_DUMMYNET);
587 		free(psi_extra, M_DUMMYNET);
588 		fq_pie_desc.ref_count--;
589 	}
590 	DN_BH_WUNLOCK();
591 }
592 
593 /*
594  * Clean up PIE status for sub-queue 'q'
595  * Stop callout timer and destroy mtx using fqpie_callout_cleanup() callout.
596  */
597 static int
598 pie_cleanup(struct fq_pie_flow *q)
599 {
600 	struct pie_status *pst  = &q->pst;
601 
602 	mtx_lock(&pst->lock_mtx);
603 	callout_reset_sbt(&pst->aqm_pie_callout,
604 		SBT_1US, 0, fqpie_callout_cleanup, q, 0);
605 	mtx_unlock(&pst->lock_mtx);
606 	return 0;
607 }
608 
609 /*
610  * Dequeue and return a pcaket from sub-queue 'q' or NULL if 'q' is empty.
611  * Also, caculate depature time or queue delay using timestamp
612  */
613  static struct mbuf *
614 pie_dequeue(struct fq_pie_flow *q, struct fq_pie_si *si)
615 {
616 	struct mbuf *m;
617 	struct dn_aqm_pie_parms *pprms;
618 	struct pie_status *pst;
619 	aqm_time_t now;
620 	aqm_time_t pkt_ts, dq_time;
621 	int32_t w;
622 
623 	pst  = &q->pst;
624 	pprms = q->pst.parms;
625 
626 	/*we extarct packet ts only when Departure Rate Estimation dis not used*/
627 	m = fq_pie_extract_head(q, &pkt_ts, si,
628 		!(pprms->flags & PIE_DEPRATEEST_ENABLED));
629 
630 	if (!m || !(pst->sflags & PIE_ACTIVE))
631 		return m;
632 
633 	now = AQM_UNOW;
634 	if (pprms->flags & PIE_DEPRATEEST_ENABLED) {
635 		/* calculate average depature time */
636 		if(pst->sflags & PIE_INMEASUREMENT) {
637 			pst->dq_count += m->m_pkthdr.len;
638 
639 			if (pst->dq_count >= PIE_DQ_THRESHOLD) {
640 				dq_time = now - pst->measurement_start;
641 
642 				/*
643 				 * if we don't have old avg dq_time i.e PIE is (re)initialized,
644 				 * don't use weight to calculate new avg_dq_time
645 				 */
646 				if(pst->avg_dq_time == 0)
647 					pst->avg_dq_time = dq_time;
648 				else {
649 					/*
650 					 * weight = PIE_DQ_THRESHOLD/2^6, but we scaled
651 					 * weight by 2^8. Thus, scaled
652 					 * weight = PIE_DQ_THRESHOLD /2^8
653 					 * */
654 					w = PIE_DQ_THRESHOLD >> 8;
655 					pst->avg_dq_time = (dq_time* w
656 						+ (pst->avg_dq_time * ((1L << 8) - w))) >> 8;
657 					pst->sflags &= ~PIE_INMEASUREMENT;
658 				}
659 			}
660 		}
661 
662 		/*
663 		 * Start new measurment cycle when the queue has
664 		 *  PIE_DQ_THRESHOLD worth of bytes.
665 		 */
666 		if(!(pst->sflags & PIE_INMEASUREMENT) &&
667 			q->stats.len_bytes >= PIE_DQ_THRESHOLD) {
668 			pst->sflags |= PIE_INMEASUREMENT;
669 			pst->measurement_start = now;
670 			pst->dq_count = 0;
671 		}
672 	}
673 	/* Optionally, use packet timestamp to estimate queue delay */
674 	else
675 		pst->current_qdelay = now - pkt_ts;
676 
677 	return m;
678 }
679 
680 
681  /*
682  * Enqueue a packet in q, subject to space and FQ-PIE queue management policy
683  * (whose parameters are in q->fs).
684  * Update stats for the queue and the scheduler.
685  * Return 0 on success, 1 on drop. The packet is consumed anyways.
686  */
687 static int
688 pie_enqueue(struct fq_pie_flow *q, struct mbuf* m, struct fq_pie_si *si)
689 {
690 	uint64_t len;
691 	struct pie_status *pst;
692 	struct dn_aqm_pie_parms *pprms;
693 	int t;
694 
695 	len = m->m_pkthdr.len;
696 	pst  = &q->pst;
697 	pprms = pst->parms;
698 	t = ENQUE;
699 
700 	/* drop/mark the packet when PIE is active and burst time elapsed */
701 	if (pst->sflags & PIE_ACTIVE && pst->burst_allowance == 0
702 		&& drop_early(pst, q->stats.len_bytes) == DROP) {
703 			/*
704 			 * if drop_prob over ECN threshold, drop the packet
705 			 * otherwise mark and enqueue it.
706 			 */
707 			if (pprms->flags & PIE_ECN_ENABLED && pst->drop_prob <
708 				(pprms->max_ecnth << (PIE_PROB_BITS - PIE_FIX_POINT_BITS))
709 				&& ecn_mark(m))
710 				t = ENQUE;
711 			else
712 				t = DROP;
713 		}
714 
715 	/* Turn PIE on when 1/3 of the queue is full */
716 	if (!(pst->sflags & PIE_ACTIVE) && q->stats.len_bytes >=
717 		pst->one_third_q_size) {
718 		fq_activate_pie(q);
719 	}
720 
721 	/*  reset burst tolerance and optinally turn PIE off*/
722 	if (pst->drop_prob == 0 && pst->current_qdelay < (pprms->qdelay_ref >> 1)
723 		&& pst->qdelay_old < (pprms->qdelay_ref >> 1)) {
724 
725 			pst->burst_allowance = pprms->max_burst;
726 		if (pprms->flags & PIE_ON_OFF_MODE_ENABLED && q->stats.len_bytes<=0)
727 			fq_deactivate_pie(pst);
728 	}
729 
730 	/* Use timestamp if Departure Rate Estimation mode is disabled */
731 	if (t != DROP && !(pprms->flags & PIE_DEPRATEEST_ENABLED)) {
732 		/* Add TS to mbuf as a TAG */
733 		struct m_tag *mtag;
734 		mtag = m_tag_locate(m, MTAG_ABI_COMPAT, DN_AQM_MTAG_TS, NULL);
735 		if (mtag == NULL)
736 			mtag = m_tag_alloc(MTAG_ABI_COMPAT, DN_AQM_MTAG_TS,
737 				sizeof(aqm_time_t), M_NOWAIT);
738 		if (mtag == NULL) {
739 			m_freem(m);
740 			t = DROP;
741 		}
742 		*(aqm_time_t *)(mtag + 1) = AQM_UNOW;
743 		m_tag_prepend(m, mtag);
744 	}
745 
746 	if (t != DROP) {
747 		mq_append(&q->mq, m);
748 		fq_update_stats(q, si, len, 0);
749 		return 0;
750 	} else {
751 		fq_update_stats(q, si, len, 1);
752 		pst->accu_prob = 0;
753 		FREE_PKT(m);
754 		return 1;
755 	}
756 
757 	return 0;
758 }
759 
760 /* Drop a packet form the head of FQ-PIE sub-queue */
761 static void
762 pie_drop_head(struct fq_pie_flow *q, struct fq_pie_si *si)
763 {
764 	struct mbuf *m = q->mq.head;
765 
766 	if (m == NULL)
767 		return;
768 	q->mq.head = m->m_nextpkt;
769 
770 	fq_update_stats(q, si, -m->m_pkthdr.len, 1);
771 
772 	if (si->main_q.ni.length == 0) /* queue is now idle */
773 			si->main_q.q_time = dn_cfg.curr_time;
774 	/* reset accu_prob after packet drop */
775 	q->pst.accu_prob = 0;
776 
777 	FREE_PKT(m);
778 }
779 
780 /*
781  * Classify a packet to queue number using Jenkins hash function.
782  * Return: queue number
783  * the input of the hash are protocol no, perturbation, src IP, dst IP,
784  * src port, dst port,
785  */
786 static inline int
787 fq_pie_classify_flow(struct mbuf *m, uint16_t fcount, struct fq_pie_si *si)
788 {
789 	struct ip *ip;
790 	struct tcphdr *th;
791 	struct udphdr *uh;
792 	uint8_t tuple[41];
793 	uint16_t hash=0;
794 
795 	ip = (struct ip *)mtodo(m, dn_tag_get(m)->iphdr_off);
796 //#ifdef INET6
797 	struct ip6_hdr *ip6;
798 	int isip6;
799 	isip6 = (ip->ip_v == 6);
800 
801 	if(isip6) {
802 		ip6 = (struct ip6_hdr *)ip;
803 		*((uint8_t *) &tuple[0]) = ip6->ip6_nxt;
804 		*((uint32_t *) &tuple[1]) = si->perturbation;
805 		memcpy(&tuple[5], ip6->ip6_src.s6_addr, 16);
806 		memcpy(&tuple[21], ip6->ip6_dst.s6_addr, 16);
807 
808 		switch (ip6->ip6_nxt) {
809 		case IPPROTO_TCP:
810 			th = (struct tcphdr *)(ip6 + 1);
811 			*((uint16_t *) &tuple[37]) = th->th_dport;
812 			*((uint16_t *) &tuple[39]) = th->th_sport;
813 			break;
814 
815 		case IPPROTO_UDP:
816 			uh = (struct udphdr *)(ip6 + 1);
817 			*((uint16_t *) &tuple[37]) = uh->uh_dport;
818 			*((uint16_t *) &tuple[39]) = uh->uh_sport;
819 			break;
820 		default:
821 			memset(&tuple[37], 0, 4);
822 		}
823 
824 		hash = jenkins_hash(tuple, 41, HASHINIT) %  fcount;
825 		return hash;
826 	}
827 //#endif
828 
829 	/* IPv4 */
830 	*((uint8_t *) &tuple[0]) = ip->ip_p;
831 	*((uint32_t *) &tuple[1]) = si->perturbation;
832 	*((uint32_t *) &tuple[5]) = ip->ip_src.s_addr;
833 	*((uint32_t *) &tuple[9]) = ip->ip_dst.s_addr;
834 
835 	switch (ip->ip_p) {
836 		case IPPROTO_TCP:
837 			th = (struct tcphdr *)(ip + 1);
838 			*((uint16_t *) &tuple[13]) = th->th_dport;
839 			*((uint16_t *) &tuple[15]) = th->th_sport;
840 			break;
841 
842 		case IPPROTO_UDP:
843 			uh = (struct udphdr *)(ip + 1);
844 			*((uint16_t *) &tuple[13]) = uh->uh_dport;
845 			*((uint16_t *) &tuple[15]) = uh->uh_sport;
846 			break;
847 		default:
848 			memset(&tuple[13], 0, 4);
849 	}
850 	hash = jenkins_hash(tuple, 17, HASHINIT) % fcount;
851 
852 	return hash;
853 }
854 
855 /*
856  * Enqueue a packet into an appropriate queue according to
857  * FQ-CoDe; algorithm.
858  */
859 static int
860 fq_pie_enqueue(struct dn_sch_inst *_si, struct dn_queue *_q,
861 	struct mbuf *m)
862 {
863 	struct fq_pie_si *si;
864 	struct fq_pie_schk *schk;
865 	struct dn_sch_fq_pie_parms *param;
866 	struct dn_queue *mainq;
867 	struct fq_pie_flow *flows;
868 	int idx, drop, i, maxidx;
869 
870 	mainq = (struct dn_queue *)(_si + 1);
871 	si = (struct fq_pie_si *)_si;
872 	flows = si->si_extra->flows;
873 	schk = (struct fq_pie_schk *)(si->_si.sched+1);
874 	param = &schk->cfg;
875 
876 	 /* classify a packet to queue number*/
877 	idx = fq_pie_classify_flow(m, param->flows_cnt, si);
878 
879 	/* enqueue packet into appropriate queue using PIE AQM.
880 	 * Note: 'pie_enqueue' function returns 1 only when it unable to
881 	 * add timestamp to packet (no limit check)*/
882 	drop = pie_enqueue(&flows[idx], m, si);
883 
884 	/* pie unable to timestamp a packet */
885 	if (drop)
886 		return 1;
887 
888 	/* If the flow (sub-queue) is not active ,then add it to tail of
889 	 * new flows list, initialize and activate it.
890 	 */
891 	if (!flows[idx].active) {
892 		STAILQ_INSERT_TAIL(&si->newflows, &flows[idx], flowchain);
893 		flows[idx].deficit = param->quantum;
894 		fq_activate_pie(&flows[idx]);
895 		flows[idx].active = 1;
896 	}
897 
898 	/* check the limit for all queues and remove a packet from the
899 	 * largest one
900 	 */
901 	if (mainq->ni.length > schk->cfg.limit) {
902 		/* find first active flow */
903 		for (maxidx = 0; maxidx < schk->cfg.flows_cnt; maxidx++)
904 			if (flows[maxidx].active)
905 				break;
906 		if (maxidx < schk->cfg.flows_cnt) {
907 			/* find the largest sub- queue */
908 			for (i = maxidx + 1; i < schk->cfg.flows_cnt; i++)
909 				if (flows[i].active && flows[i].stats.length >
910 					flows[maxidx].stats.length)
911 					maxidx = i;
912 			pie_drop_head(&flows[maxidx], si);
913 			drop = 1;
914 		}
915 	}
916 
917 	return drop;
918 }
919 
920 /*
921  * Dequeue a packet from an appropriate queue according to
922  * FQ-CoDel algorithm.
923  */
924 static struct mbuf *
925 fq_pie_dequeue(struct dn_sch_inst *_si)
926 {
927 	struct fq_pie_si *si;
928 	struct fq_pie_schk *schk;
929 	struct dn_sch_fq_pie_parms *param;
930 	struct fq_pie_flow *f;
931 	struct mbuf *mbuf;
932 	struct fq_pie_list *fq_pie_flowlist;
933 
934 	si = (struct fq_pie_si *)_si;
935 	schk = (struct fq_pie_schk *)(si->_si.sched+1);
936 	param = &schk->cfg;
937 
938 	do {
939 		/* select a list to start with */
940 		if (STAILQ_EMPTY(&si->newflows))
941 			fq_pie_flowlist = &si->oldflows;
942 		else
943 			fq_pie_flowlist = &si->newflows;
944 
945 		/* Both new and old queue lists are empty, return NULL */
946 		if (STAILQ_EMPTY(fq_pie_flowlist))
947 			return NULL;
948 
949 		f = STAILQ_FIRST(fq_pie_flowlist);
950 		while (f != NULL)	{
951 			/* if there is no flow(sub-queue) deficit, increase deficit
952 			 * by quantum, move the flow to the tail of old flows list
953 			 * and try another flow.
954 			 * Otherwise, the flow will be used for dequeue.
955 			 */
956 			if (f->deficit < 0) {
957 				 f->deficit += param->quantum;
958 				 STAILQ_REMOVE_HEAD(fq_pie_flowlist, flowchain);
959 				 STAILQ_INSERT_TAIL(&si->oldflows, f, flowchain);
960 			 } else
961 				 break;
962 
963 			f = STAILQ_FIRST(fq_pie_flowlist);
964 		}
965 
966 		/* the new flows list is empty, try old flows list */
967 		if (STAILQ_EMPTY(fq_pie_flowlist))
968 			continue;
969 
970 		/* Dequeue a packet from the selected flow */
971 		mbuf = pie_dequeue(f, si);
972 
973 		/* pie did not return a packet */
974 		if (!mbuf) {
975 			/* If the selected flow belongs to new flows list, then move
976 			 * it to the tail of old flows list. Otherwise, deactivate it and
977 			 * remove it from the old list and
978 			 */
979 			if (fq_pie_flowlist == &si->newflows) {
980 				STAILQ_REMOVE_HEAD(fq_pie_flowlist, flowchain);
981 				STAILQ_INSERT_TAIL(&si->oldflows, f, flowchain);
982 			}	else {
983 				f->active = 0;
984 				fq_deactivate_pie(&f->pst);
985 				STAILQ_REMOVE_HEAD(fq_pie_flowlist, flowchain);
986 			}
987 			/* start again */
988 			continue;
989 		}
990 
991 		/* we have a packet to return,
992 		 * update flow deficit and return the packet*/
993 		f->deficit -= mbuf->m_pkthdr.len;
994 		return mbuf;
995 
996 	} while (1);
997 
998 	/* unreachable point */
999 	return NULL;
1000 }
1001 
1002 /*
1003  * Initialize fq_pie scheduler instance.
1004  * also, allocate memory for flows array.
1005  */
1006 static int
1007 fq_pie_new_sched(struct dn_sch_inst *_si)
1008 {
1009 	struct fq_pie_si *si;
1010 	struct dn_queue *q;
1011 	struct fq_pie_schk *schk;
1012 	struct fq_pie_flow *flows;
1013 	int i;
1014 
1015 	si = (struct fq_pie_si *)_si;
1016 	schk = (struct fq_pie_schk *)(_si->sched+1);
1017 
1018 	if(si->si_extra) {
1019 		D("si already configured!");
1020 		return 0;
1021 	}
1022 
1023 	/* init the main queue */
1024 	q = &si->main_q;
1025 	set_oid(&q->ni.oid, DN_QUEUE, sizeof(*q));
1026 	q->_si = _si;
1027 	q->fs = _si->sched->fs;
1028 
1029 	/* allocate memory for scheduler instance extra vars */
1030 	si->si_extra = malloc(sizeof(struct fq_pie_si_extra),
1031 		 M_DUMMYNET, M_NOWAIT | M_ZERO);
1032 	if (si->si_extra == NULL) {
1033 		D("cannot allocate memory for fq_pie si extra vars");
1034 		return ENOMEM ;
1035 	}
1036 	/* allocate memory for flows array */
1037 	si->si_extra->flows = mallocarray(schk->cfg.flows_cnt,
1038 	    sizeof(struct fq_pie_flow), M_DUMMYNET, M_NOWAIT | M_ZERO);
1039 	flows = si->si_extra->flows;
1040 	if (flows == NULL) {
1041 		free(si->si_extra, M_DUMMYNET);
1042 		si->si_extra = NULL;
1043 		D("cannot allocate memory for fq_pie flows");
1044 		return ENOMEM ;
1045 	}
1046 
1047 	/* init perturbation for this si */
1048 	si->perturbation = random();
1049 	si->si_extra->nr_active_q = 0;
1050 
1051 	/* init the old and new flows lists */
1052 	STAILQ_INIT(&si->newflows);
1053 	STAILQ_INIT(&si->oldflows);
1054 
1055 	/* init the flows (sub-queues) */
1056 	for (i = 0; i < schk->cfg.flows_cnt; i++) {
1057 		flows[i].pst.parms = &schk->cfg.pcfg;
1058 		flows[i].psi_extra = si->si_extra;
1059 		pie_init(&flows[i], schk);
1060 	}
1061 
1062 	fq_pie_desc.ref_count++;
1063 
1064 	return 0;
1065 }
1066 
1067 
1068 /*
1069  * Free fq_pie scheduler instance.
1070  */
1071 static int
1072 fq_pie_free_sched(struct dn_sch_inst *_si)
1073 {
1074 	struct fq_pie_si *si;
1075 	struct fq_pie_schk *schk;
1076 	struct fq_pie_flow *flows;
1077 	int i;
1078 
1079 	si = (struct fq_pie_si *)_si;
1080 	schk = (struct fq_pie_schk *)(_si->sched+1);
1081 	flows = si->si_extra->flows;
1082 	for (i = 0; i < schk->cfg.flows_cnt; i++) {
1083 		pie_cleanup(&flows[i]);
1084 	}
1085 	si->si_extra = NULL;
1086 	return 0;
1087 }
1088 
1089 /*
1090  * Configure FQ-PIE scheduler.
1091  * the configurations for the scheduler is passed fromipfw  userland.
1092  */
1093 static int
1094 fq_pie_config(struct dn_schk *_schk)
1095 {
1096 	struct fq_pie_schk *schk;
1097 	struct dn_extra_parms *ep;
1098 	struct dn_sch_fq_pie_parms *fqp_cfg;
1099 
1100 	schk = (struct fq_pie_schk *)(_schk+1);
1101 	ep = (struct dn_extra_parms *) _schk->cfg;
1102 
1103 	/* par array contains fq_pie configuration as follow
1104 	 * PIE: 0- qdelay_ref,1- tupdate, 2- max_burst
1105 	 * 3- max_ecnth, 4- alpha, 5- beta, 6- flags
1106 	 * FQ_PIE: 7- quantum, 8- limit, 9- flows
1107 	 */
1108 	if (ep && ep->oid.len ==sizeof(*ep) &&
1109 		ep->oid.subtype == DN_SCH_PARAMS) {
1110 
1111 		fqp_cfg = &schk->cfg;
1112 		if (ep->par[0] < 0)
1113 			fqp_cfg->pcfg.qdelay_ref = fq_pie_sysctl.pcfg.qdelay_ref;
1114 		else
1115 			fqp_cfg->pcfg.qdelay_ref = ep->par[0];
1116 		if (ep->par[1] < 0)
1117 			fqp_cfg->pcfg.tupdate = fq_pie_sysctl.pcfg.tupdate;
1118 		else
1119 			fqp_cfg->pcfg.tupdate = ep->par[1];
1120 		if (ep->par[2] < 0)
1121 			fqp_cfg->pcfg.max_burst = fq_pie_sysctl.pcfg.max_burst;
1122 		else
1123 			fqp_cfg->pcfg.max_burst = ep->par[2];
1124 		if (ep->par[3] < 0)
1125 			fqp_cfg->pcfg.max_ecnth = fq_pie_sysctl.pcfg.max_ecnth;
1126 		else
1127 			fqp_cfg->pcfg.max_ecnth = ep->par[3];
1128 		if (ep->par[4] < 0)
1129 			fqp_cfg->pcfg.alpha = fq_pie_sysctl.pcfg.alpha;
1130 		else
1131 			fqp_cfg->pcfg.alpha = ep->par[4];
1132 		if (ep->par[5] < 0)
1133 			fqp_cfg->pcfg.beta = fq_pie_sysctl.pcfg.beta;
1134 		else
1135 			fqp_cfg->pcfg.beta = ep->par[5];
1136 		if (ep->par[6] < 0)
1137 			fqp_cfg->pcfg.flags = 0;
1138 		else
1139 			fqp_cfg->pcfg.flags = ep->par[6];
1140 
1141 		/* FQ configurations */
1142 		if (ep->par[7] < 0)
1143 			fqp_cfg->quantum = fq_pie_sysctl.quantum;
1144 		else
1145 			fqp_cfg->quantum = ep->par[7];
1146 		if (ep->par[8] < 0)
1147 			fqp_cfg->limit = fq_pie_sysctl.limit;
1148 		else
1149 			fqp_cfg->limit = ep->par[8];
1150 		if (ep->par[9] < 0)
1151 			fqp_cfg->flows_cnt = fq_pie_sysctl.flows_cnt;
1152 		else
1153 			fqp_cfg->flows_cnt = ep->par[9];
1154 
1155 		/* Bound the configurations */
1156 		fqp_cfg->pcfg.qdelay_ref = BOUND_VAR(fqp_cfg->pcfg.qdelay_ref,
1157 			1, 5 * AQM_TIME_1S);
1158 		fqp_cfg->pcfg.tupdate = BOUND_VAR(fqp_cfg->pcfg.tupdate,
1159 			1, 5 * AQM_TIME_1S);
1160 		fqp_cfg->pcfg.max_burst = BOUND_VAR(fqp_cfg->pcfg.max_burst,
1161 			0, 5 * AQM_TIME_1S);
1162 		fqp_cfg->pcfg.max_ecnth = BOUND_VAR(fqp_cfg->pcfg.max_ecnth,
1163 			0, PIE_SCALE);
1164 		fqp_cfg->pcfg.alpha = BOUND_VAR(fqp_cfg->pcfg.alpha, 0, 7 * PIE_SCALE);
1165 		fqp_cfg->pcfg.beta = BOUND_VAR(fqp_cfg->pcfg.beta, 0, 7 * PIE_SCALE);
1166 
1167 		fqp_cfg->quantum = BOUND_VAR(fqp_cfg->quantum,1,9000);
1168 		fqp_cfg->limit= BOUND_VAR(fqp_cfg->limit,1,20480);
1169 		fqp_cfg->flows_cnt= BOUND_VAR(fqp_cfg->flows_cnt,1,65536);
1170 	}
1171 	else {
1172 		D("Wrong parameters for fq_pie scheduler");
1173 		return 1;
1174 	}
1175 
1176 	return 0;
1177 }
1178 
1179 /*
1180  * Return FQ-PIE scheduler configurations
1181  * the configurations for the scheduler is passed to userland.
1182  */
1183 static int
1184 fq_pie_getconfig (struct dn_schk *_schk, struct dn_extra_parms *ep) {
1185 
1186 	struct fq_pie_schk *schk = (struct fq_pie_schk *)(_schk+1);
1187 	struct dn_sch_fq_pie_parms *fqp_cfg;
1188 
1189 	fqp_cfg = &schk->cfg;
1190 
1191 	strcpy(ep->name, fq_pie_desc.name);
1192 	ep->par[0] = fqp_cfg->pcfg.qdelay_ref;
1193 	ep->par[1] = fqp_cfg->pcfg.tupdate;
1194 	ep->par[2] = fqp_cfg->pcfg.max_burst;
1195 	ep->par[3] = fqp_cfg->pcfg.max_ecnth;
1196 	ep->par[4] = fqp_cfg->pcfg.alpha;
1197 	ep->par[5] = fqp_cfg->pcfg.beta;
1198 	ep->par[6] = fqp_cfg->pcfg.flags;
1199 
1200 	ep->par[7] = fqp_cfg->quantum;
1201 	ep->par[8] = fqp_cfg->limit;
1202 	ep->par[9] = fqp_cfg->flows_cnt;
1203 
1204 	return 0;
1205 }
1206 
1207 /*
1208  *  FQ-PIE scheduler descriptor
1209  * contains the type of the scheduler, the name, the size of extra
1210  * data structures, and function pointers.
1211  */
1212 static struct dn_alg fq_pie_desc = {
1213 	_SI( .type = )  DN_SCHED_FQ_PIE,
1214 	_SI( .name = ) "FQ_PIE",
1215 	_SI( .flags = ) 0,
1216 
1217 	_SI( .schk_datalen = ) sizeof(struct fq_pie_schk),
1218 	_SI( .si_datalen = ) sizeof(struct fq_pie_si) - sizeof(struct dn_sch_inst),
1219 	_SI( .q_datalen = ) 0,
1220 
1221 	_SI( .enqueue = ) fq_pie_enqueue,
1222 	_SI( .dequeue = ) fq_pie_dequeue,
1223 	_SI( .config = ) fq_pie_config, /* new sched i.e. sched X config ...*/
1224 	_SI( .destroy = ) NULL,  /*sched x delete */
1225 	_SI( .new_sched = ) fq_pie_new_sched, /* new schd instance */
1226 	_SI( .free_sched = ) fq_pie_free_sched,	/* delete schd instance */
1227 	_SI( .new_fsk = ) NULL,
1228 	_SI( .free_fsk = ) NULL,
1229 	_SI( .new_queue = ) NULL,
1230 	_SI( .free_queue = ) NULL,
1231 	_SI( .getconfig = )  fq_pie_getconfig,
1232 	_SI( .ref_count = ) 0
1233 };
1234 
1235 DECLARE_DNSCHED_MODULE(dn_fq_pie, &fq_pie_desc);
1236