2 * net/sched/sch_qfq.c Quick Fair Queueing Scheduler.
4 * Copyright (c) 2009 Fabio Checconi, Luigi Rizzo, and Paolo Valente.
6 * This program is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU General Public License
8 * version 2 as published by the Free Software Foundation.
11 #include <linux/module.h>
12 #include <linux/init.h>
13 #include <linux/bitops.h>
14 #include <linux/errno.h>
15 #include <linux/netdevice.h>
16 #include <linux/pkt_sched.h>
17 #include <net/sch_generic.h>
18 #include <net/pkt_sched.h>
19 #include <net/pkt_cls.h>
22 /* Quick Fair Queueing
27 Fabio Checconi, Luigi Rizzo, and Paolo Valente: "QFQ: Efficient
28 Packet Scheduling with Tight Bandwidth Distribution Guarantees."
31 http://retis.sssup.it/~fabio/linux/qfq/
36 Virtual time computations.
38 S, F and V are all computed in fixed point arithmetic with
39 FRAC_BITS decimal bits.
41 QFQ_MAX_INDEX is the maximum index allowed for a group. We need
43 QFQ_MAX_WSHIFT is the maximum power of two supported as a weight.
45 The layout of the bits is as below:
47 [ MTU_SHIFT ][ FRAC_BITS ]
48 [ MAX_INDEX ][ MIN_SLOT_SHIFT ]
52 where MIN_SLOT_SHIFT is derived by difference from the others.
54 The max group index corresponds to Lmax/w_min, where
55 Lmax=1<<MTU_SHIFT, w_min = 1 .
56 From this, and knowing how many groups (MAX_INDEX) we want,
57 we can derive the shift corresponding to each group.
59 Because we often need to compute
60 F = S + len/w_i and V = V + len/wsum
61 instead of storing w_i store the value
62 inv_w = (1<<FRAC_BITS)/w_i
63 so we can do F = S + len * inv_w * wsum.
64 We use W_TOT in the formulas so we can easily move between
65 static and adaptive weight sum.
67 The per-scheduler-instance data contain all the data structures
68 for the scheduler: bitmaps and bucket lists.
73 * Maximum number of consecutive slots occupied by backlogged classes
76 #define QFQ_MAX_SLOTS 32
79 * Shifts used for class<->group mapping. We allow class weights that are
80 * in the range [1, 2^MAX_WSHIFT], and we try to map each class i to the
81 * group with the smallest index that can support the L_i / r_i configured
84 * grp->index is the index of the group; and grp->slot_shift
85 * is the shift for the corresponding (scaled) sigma_i.
87 #define QFQ_MAX_INDEX 19
88 #define QFQ_MAX_WSHIFT 16
90 #define QFQ_MAX_WEIGHT (1<<QFQ_MAX_WSHIFT)
91 #define QFQ_MAX_WSUM (2*QFQ_MAX_WEIGHT)
93 #define FRAC_BITS 30 /* fixed point arithmetic */
94 #define ONE_FP (1UL << FRAC_BITS)
95 #define IWSUM (ONE_FP/QFQ_MAX_WSUM)
97 #define QFQ_MTU_SHIFT 11
98 #define QFQ_MIN_SLOT_SHIFT (FRAC_BITS + QFQ_MTU_SHIFT - QFQ_MAX_INDEX)
101 * Possible group states. These values are used as indexes for the bitmaps
102 * array of struct qfq_queue.
104 enum qfq_state
{ ER
, IR
, EB
, IB
, QFQ_MAX_STATE
};
109 struct Qdisc_class_common common
;
112 unsigned int filter_cnt
;
114 struct gnet_stats_basic_packed bstats
;
115 struct gnet_stats_queue qstats
;
116 struct gnet_stats_rate_est rate_est
;
119 struct hlist_node next
; /* Link for the slot list. */
120 u64 S
, F
; /* flow timestamps (exact) */
122 /* group we belong to. In principle we would need the index,
123 * which is log_2(lmax/weight), but we never reference it
124 * directly, only the group.
126 struct qfq_group
*grp
;
128 /* these are copied from the flowset. */
129 u32 inv_w
; /* ONE_FP/weight */
130 u32 lmax
; /* Max packet size for this flow. */
134 u64 S
, F
; /* group timestamps (approx). */
135 unsigned int slot_shift
; /* Slot shift. */
136 unsigned int index
; /* Group index. */
137 unsigned int front
; /* Index of the front slot. */
138 unsigned long full_slots
; /* non-empty slots */
140 /* Array of RR lists of active classes. */
141 struct hlist_head slots
[QFQ_MAX_SLOTS
];
145 struct tcf_proto
*filter_list
;
146 struct Qdisc_class_hash clhash
;
148 u64 V
; /* Precise virtual time. */
149 u32 wsum
; /* weight sum */
151 unsigned long bitmaps
[QFQ_MAX_STATE
]; /* Group bitmaps. */
152 struct qfq_group groups
[QFQ_MAX_INDEX
+ 1]; /* The groups. */
155 static struct qfq_class
*qfq_find_class(struct Qdisc
*sch
, u32 classid
)
157 struct qfq_sched
*q
= qdisc_priv(sch
);
158 struct Qdisc_class_common
*clc
;
160 clc
= qdisc_class_find(&q
->clhash
, classid
);
163 return container_of(clc
, struct qfq_class
, common
);
166 static void qfq_purge_queue(struct qfq_class
*cl
)
168 unsigned int len
= cl
->qdisc
->q
.qlen
;
170 qdisc_reset(cl
->qdisc
);
171 qdisc_tree_decrease_qlen(cl
->qdisc
, len
);
174 static const struct nla_policy qfq_policy
[TCA_QFQ_MAX
+ 1] = {
175 [TCA_QFQ_WEIGHT
] = { .type
= NLA_U32
},
176 [TCA_QFQ_LMAX
] = { .type
= NLA_U32
},
180 * Calculate a flow index, given its weight and maximum packet length.
181 * index = log_2(maxlen/weight) but we need to apply the scaling.
182 * This is used only once at flow creation.
184 static int qfq_calc_index(u32 inv_w
, unsigned int maxlen
)
186 u64 slot_size
= (u64
)maxlen
* inv_w
;
187 unsigned long size_map
;
190 size_map
= slot_size
>> QFQ_MIN_SLOT_SHIFT
;
194 index
= __fls(size_map
) + 1; /* basically a log_2 */
195 index
-= !(slot_size
- (1ULL << (index
+ QFQ_MIN_SLOT_SHIFT
- 1)));
200 pr_debug("qfq calc_index: W = %lu, L = %u, I = %d\n",
201 (unsigned long) ONE_FP
/inv_w
, maxlen
, index
);
206 /* Length of the next packet (0 if the queue is empty). */
207 static unsigned int qdisc_peek_len(struct Qdisc
*sch
)
211 skb
= sch
->ops
->peek(sch
);
212 return skb
? qdisc_pkt_len(skb
) : 0;
215 static void qfq_deactivate_class(struct qfq_sched
*, struct qfq_class
*);
216 static void qfq_activate_class(struct qfq_sched
*q
, struct qfq_class
*cl
,
219 static void qfq_update_class_params(struct qfq_sched
*q
, struct qfq_class
*cl
,
220 u32 lmax
, u32 inv_w
, int delta_w
)
224 /* update qfq-specific data */
227 i
= qfq_calc_index(cl
->inv_w
, cl
->lmax
);
229 cl
->grp
= &q
->groups
[i
];
234 static int qfq_change_class(struct Qdisc
*sch
, u32 classid
, u32 parentid
,
235 struct nlattr
**tca
, unsigned long *arg
)
237 struct qfq_sched
*q
= qdisc_priv(sch
);
238 struct qfq_class
*cl
= (struct qfq_class
*)*arg
;
239 struct nlattr
*tb
[TCA_QFQ_MAX
+ 1];
240 u32 weight
, lmax
, inv_w
;
244 if (tca
[TCA_OPTIONS
] == NULL
) {
245 pr_notice("qfq: no options\n");
249 err
= nla_parse_nested(tb
, TCA_QFQ_MAX
, tca
[TCA_OPTIONS
], qfq_policy
);
253 if (tb
[TCA_QFQ_WEIGHT
]) {
254 weight
= nla_get_u32(tb
[TCA_QFQ_WEIGHT
]);
255 if (!weight
|| weight
> (1UL << QFQ_MAX_WSHIFT
)) {
256 pr_notice("qfq: invalid weight %u\n", weight
);
262 inv_w
= ONE_FP
/ weight
;
263 weight
= ONE_FP
/ inv_w
;
264 delta_w
= weight
- (cl
? ONE_FP
/ cl
->inv_w
: 0);
265 if (q
->wsum
+ delta_w
> QFQ_MAX_WSUM
) {
266 pr_notice("qfq: total weight out of range (%u + %u)\n",
271 if (tb
[TCA_QFQ_LMAX
]) {
272 lmax
= nla_get_u32(tb
[TCA_QFQ_LMAX
]);
273 if (!lmax
|| lmax
> (1UL << QFQ_MTU_SHIFT
)) {
274 pr_notice("qfq: invalid max length %u\n", lmax
);
278 lmax
= 1UL << QFQ_MTU_SHIFT
;
281 bool need_reactivation
= false;
284 err
= gen_replace_estimator(&cl
->bstats
, &cl
->rate_est
,
285 qdisc_root_sleeping_lock(sch
),
291 if (lmax
== cl
->lmax
&& inv_w
== cl
->inv_w
)
292 return 0; /* nothing to update */
294 i
= qfq_calc_index(inv_w
, lmax
);
296 if (&q
->groups
[i
] != cl
->grp
&& cl
->qdisc
->q
.qlen
> 0) {
298 * shift cl->F back, to not charge the
299 * class for the not-yet-served head
303 /* remove class from its slot in the old group */
304 qfq_deactivate_class(q
, cl
);
305 need_reactivation
= true;
308 qfq_update_class_params(q
, cl
, lmax
, inv_w
, delta_w
);
310 if (need_reactivation
) /* activate in new group */
311 qfq_activate_class(q
, cl
, qdisc_peek_len(cl
->qdisc
));
312 sch_tree_unlock(sch
);
317 cl
= kzalloc(sizeof(struct qfq_class
), GFP_KERNEL
);
322 cl
->common
.classid
= classid
;
324 qfq_update_class_params(q
, cl
, lmax
, inv_w
, delta_w
);
326 cl
->qdisc
= qdisc_create_dflt(sch
->dev_queue
,
327 &pfifo_qdisc_ops
, classid
);
328 if (cl
->qdisc
== NULL
)
329 cl
->qdisc
= &noop_qdisc
;
332 err
= gen_new_estimator(&cl
->bstats
, &cl
->rate_est
,
333 qdisc_root_sleeping_lock(sch
),
336 qdisc_destroy(cl
->qdisc
);
343 qdisc_class_hash_insert(&q
->clhash
, &cl
->common
);
344 sch_tree_unlock(sch
);
346 qdisc_class_hash_grow(sch
, &q
->clhash
);
348 *arg
= (unsigned long)cl
;
352 static void qfq_destroy_class(struct Qdisc
*sch
, struct qfq_class
*cl
)
354 struct qfq_sched
*q
= qdisc_priv(sch
);
357 q
->wsum
-= ONE_FP
/ cl
->inv_w
;
361 gen_kill_estimator(&cl
->bstats
, &cl
->rate_est
);
362 qdisc_destroy(cl
->qdisc
);
366 static int qfq_delete_class(struct Qdisc
*sch
, unsigned long arg
)
368 struct qfq_sched
*q
= qdisc_priv(sch
);
369 struct qfq_class
*cl
= (struct qfq_class
*)arg
;
371 if (cl
->filter_cnt
> 0)
377 qdisc_class_hash_remove(&q
->clhash
, &cl
->common
);
379 BUG_ON(--cl
->refcnt
== 0);
381 * This shouldn't happen: we "hold" one cops->get() when called
382 * from tc_ctl_tclass; the destroy method is done from cops->put().
385 sch_tree_unlock(sch
);
389 static unsigned long qfq_get_class(struct Qdisc
*sch
, u32 classid
)
391 struct qfq_class
*cl
= qfq_find_class(sch
, classid
);
396 return (unsigned long)cl
;
399 static void qfq_put_class(struct Qdisc
*sch
, unsigned long arg
)
401 struct qfq_class
*cl
= (struct qfq_class
*)arg
;
403 if (--cl
->refcnt
== 0)
404 qfq_destroy_class(sch
, cl
);
407 static struct tcf_proto
**qfq_tcf_chain(struct Qdisc
*sch
, unsigned long cl
)
409 struct qfq_sched
*q
= qdisc_priv(sch
);
414 return &q
->filter_list
;
417 static unsigned long qfq_bind_tcf(struct Qdisc
*sch
, unsigned long parent
,
420 struct qfq_class
*cl
= qfq_find_class(sch
, classid
);
425 return (unsigned long)cl
;
428 static void qfq_unbind_tcf(struct Qdisc
*sch
, unsigned long arg
)
430 struct qfq_class
*cl
= (struct qfq_class
*)arg
;
435 static int qfq_graft_class(struct Qdisc
*sch
, unsigned long arg
,
436 struct Qdisc
*new, struct Qdisc
**old
)
438 struct qfq_class
*cl
= (struct qfq_class
*)arg
;
441 new = qdisc_create_dflt(sch
->dev_queue
,
442 &pfifo_qdisc_ops
, cl
->common
.classid
);
451 sch_tree_unlock(sch
);
455 static struct Qdisc
*qfq_class_leaf(struct Qdisc
*sch
, unsigned long arg
)
457 struct qfq_class
*cl
= (struct qfq_class
*)arg
;
462 static int qfq_dump_class(struct Qdisc
*sch
, unsigned long arg
,
463 struct sk_buff
*skb
, struct tcmsg
*tcm
)
465 struct qfq_class
*cl
= (struct qfq_class
*)arg
;
468 tcm
->tcm_parent
= TC_H_ROOT
;
469 tcm
->tcm_handle
= cl
->common
.classid
;
470 tcm
->tcm_info
= cl
->qdisc
->handle
;
472 nest
= nla_nest_start(skb
, TCA_OPTIONS
);
474 goto nla_put_failure
;
475 if (nla_put_u32(skb
, TCA_QFQ_WEIGHT
, ONE_FP
/cl
->inv_w
) ||
476 nla_put_u32(skb
, TCA_QFQ_LMAX
, cl
->lmax
))
477 goto nla_put_failure
;
478 return nla_nest_end(skb
, nest
);
481 nla_nest_cancel(skb
, nest
);
485 static int qfq_dump_class_stats(struct Qdisc
*sch
, unsigned long arg
,
488 struct qfq_class
*cl
= (struct qfq_class
*)arg
;
489 struct tc_qfq_stats xstats
;
491 memset(&xstats
, 0, sizeof(xstats
));
492 cl
->qdisc
->qstats
.qlen
= cl
->qdisc
->q
.qlen
;
494 xstats
.weight
= ONE_FP
/cl
->inv_w
;
495 xstats
.lmax
= cl
->lmax
;
497 if (gnet_stats_copy_basic(d
, &cl
->bstats
) < 0 ||
498 gnet_stats_copy_rate_est(d
, &cl
->bstats
, &cl
->rate_est
) < 0 ||
499 gnet_stats_copy_queue(d
, &cl
->qdisc
->qstats
) < 0)
502 return gnet_stats_copy_app(d
, &xstats
, sizeof(xstats
));
505 static void qfq_walk(struct Qdisc
*sch
, struct qdisc_walker
*arg
)
507 struct qfq_sched
*q
= qdisc_priv(sch
);
508 struct qfq_class
*cl
;
509 struct hlist_node
*n
;
515 for (i
= 0; i
< q
->clhash
.hashsize
; i
++) {
516 hlist_for_each_entry(cl
, n
, &q
->clhash
.hash
[i
], common
.hnode
) {
517 if (arg
->count
< arg
->skip
) {
521 if (arg
->fn(sch
, (unsigned long)cl
, arg
) < 0) {
530 static struct qfq_class
*qfq_classify(struct sk_buff
*skb
, struct Qdisc
*sch
,
533 struct qfq_sched
*q
= qdisc_priv(sch
);
534 struct qfq_class
*cl
;
535 struct tcf_result res
;
538 if (TC_H_MAJ(skb
->priority
^ sch
->handle
) == 0) {
539 pr_debug("qfq_classify: found %d\n", skb
->priority
);
540 cl
= qfq_find_class(sch
, skb
->priority
);
545 *qerr
= NET_XMIT_SUCCESS
| __NET_XMIT_BYPASS
;
546 result
= tc_classify(skb
, q
->filter_list
, &res
);
548 #ifdef CONFIG_NET_CLS_ACT
552 *qerr
= NET_XMIT_SUCCESS
| __NET_XMIT_STOLEN
;
557 cl
= (struct qfq_class
*)res
.class;
559 cl
= qfq_find_class(sch
, res
.classid
);
566 /* Generic comparison function, handling wraparound. */
567 static inline int qfq_gt(u64 a
, u64 b
)
569 return (s64
)(a
- b
) > 0;
572 /* Round a precise timestamp to its slotted value. */
573 static inline u64
qfq_round_down(u64 ts
, unsigned int shift
)
575 return ts
& ~((1ULL << shift
) - 1);
578 /* return the pointer to the group with lowest index in the bitmap */
579 static inline struct qfq_group
*qfq_ffs(struct qfq_sched
*q
,
580 unsigned long bitmap
)
582 int index
= __ffs(bitmap
);
583 return &q
->groups
[index
];
585 /* Calculate a mask to mimic what would be ffs_from(). */
586 static inline unsigned long mask_from(unsigned long bitmap
, int from
)
588 return bitmap
& ~((1UL << from
) - 1);
592 * The state computation relies on ER=0, IR=1, EB=2, IB=3
593 * First compute eligibility comparing grp->S, q->V,
594 * then check if someone is blocking us and possibly add EB
596 static int qfq_calc_state(struct qfq_sched
*q
, const struct qfq_group
*grp
)
598 /* if S > V we are not eligible */
599 unsigned int state
= qfq_gt(grp
->S
, q
->V
);
600 unsigned long mask
= mask_from(q
->bitmaps
[ER
], grp
->index
);
601 struct qfq_group
*next
;
604 next
= qfq_ffs(q
, mask
);
605 if (qfq_gt(grp
->F
, next
->F
))
615 * q->bitmaps[dst] |= q->bitmaps[src] & mask;
616 * q->bitmaps[src] &= ~mask;
617 * but we should make sure that src != dst
619 static inline void qfq_move_groups(struct qfq_sched
*q
, unsigned long mask
,
622 q
->bitmaps
[dst
] |= q
->bitmaps
[src
] & mask
;
623 q
->bitmaps
[src
] &= ~mask
;
626 static void qfq_unblock_groups(struct qfq_sched
*q
, int index
, u64 old_F
)
628 unsigned long mask
= mask_from(q
->bitmaps
[ER
], index
+ 1);
629 struct qfq_group
*next
;
632 next
= qfq_ffs(q
, mask
);
633 if (!qfq_gt(next
->F
, old_F
))
637 mask
= (1UL << index
) - 1;
638 qfq_move_groups(q
, mask
, EB
, ER
);
639 qfq_move_groups(q
, mask
, IB
, IR
);
646 old_V >>= QFQ_MIN_SLOT_SHIFT;
652 static void qfq_make_eligible(struct qfq_sched
*q
, u64 old_V
)
654 unsigned long vslot
= q
->V
>> QFQ_MIN_SLOT_SHIFT
;
655 unsigned long old_vslot
= old_V
>> QFQ_MIN_SLOT_SHIFT
;
657 if (vslot
!= old_vslot
) {
658 unsigned long mask
= (1UL << fls(vslot
^ old_vslot
)) - 1;
659 qfq_move_groups(q
, mask
, IR
, ER
);
660 qfq_move_groups(q
, mask
, IB
, EB
);
666 * XXX we should make sure that slot becomes less than 32.
667 * This is guaranteed by the input values.
668 * roundedS is always cl->S rounded on grp->slot_shift bits.
670 static void qfq_slot_insert(struct qfq_group
*grp
, struct qfq_class
*cl
,
673 u64 slot
= (roundedS
- grp
->S
) >> grp
->slot_shift
;
674 unsigned int i
= (grp
->front
+ slot
) % QFQ_MAX_SLOTS
;
676 hlist_add_head(&cl
->next
, &grp
->slots
[i
]);
677 __set_bit(slot
, &grp
->full_slots
);
680 /* Maybe introduce hlist_first_entry?? */
681 static struct qfq_class
*qfq_slot_head(struct qfq_group
*grp
)
683 return hlist_entry(grp
->slots
[grp
->front
].first
,
684 struct qfq_class
, next
);
688 * remove the entry from the slot
690 static void qfq_front_slot_remove(struct qfq_group
*grp
)
692 struct qfq_class
*cl
= qfq_slot_head(grp
);
695 hlist_del(&cl
->next
);
696 if (hlist_empty(&grp
->slots
[grp
->front
]))
697 __clear_bit(0, &grp
->full_slots
);
701 * Returns the first full queue in a group. As a side effect,
702 * adjust the bucket list so the first non-empty bucket is at
703 * position 0 in full_slots.
705 static struct qfq_class
*qfq_slot_scan(struct qfq_group
*grp
)
709 pr_debug("qfq slot_scan: grp %u full %#lx\n",
710 grp
->index
, grp
->full_slots
);
712 if (grp
->full_slots
== 0)
715 i
= __ffs(grp
->full_slots
); /* zero based */
717 grp
->front
= (grp
->front
+ i
) % QFQ_MAX_SLOTS
;
718 grp
->full_slots
>>= i
;
721 return qfq_slot_head(grp
);
725 * adjust the bucket list. When the start time of a group decreases,
726 * we move the index down (modulo QFQ_MAX_SLOTS) so we don't need to
727 * move the objects. The mask of occupied slots must be shifted
728 * because we use ffs() to find the first non-empty slot.
729 * This covers decreases in the group's start time, but what about
730 * increases of the start time ?
731 * Here too we should make sure that i is less than 32
733 static void qfq_slot_rotate(struct qfq_group
*grp
, u64 roundedS
)
735 unsigned int i
= (grp
->S
- roundedS
) >> grp
->slot_shift
;
737 grp
->full_slots
<<= i
;
738 grp
->front
= (grp
->front
- i
) % QFQ_MAX_SLOTS
;
741 static void qfq_update_eligible(struct qfq_sched
*q
, u64 old_V
)
743 struct qfq_group
*grp
;
744 unsigned long ineligible
;
746 ineligible
= q
->bitmaps
[IR
] | q
->bitmaps
[IB
];
748 if (!q
->bitmaps
[ER
]) {
749 grp
= qfq_ffs(q
, ineligible
);
750 if (qfq_gt(grp
->S
, q
->V
))
753 qfq_make_eligible(q
, old_V
);
758 * Updates the class, returns true if also the group needs to be updated.
760 static bool qfq_update_class(struct qfq_group
*grp
, struct qfq_class
*cl
)
762 unsigned int len
= qdisc_peek_len(cl
->qdisc
);
766 qfq_front_slot_remove(grp
); /* queue is empty */
770 cl
->F
= cl
->S
+ (u64
)len
* cl
->inv_w
;
771 roundedS
= qfq_round_down(cl
->S
, grp
->slot_shift
);
772 if (roundedS
== grp
->S
)
775 qfq_front_slot_remove(grp
);
776 qfq_slot_insert(grp
, cl
, roundedS
);
782 static struct sk_buff
*qfq_dequeue(struct Qdisc
*sch
)
784 struct qfq_sched
*q
= qdisc_priv(sch
);
785 struct qfq_group
*grp
;
786 struct qfq_class
*cl
;
794 grp
= qfq_ffs(q
, q
->bitmaps
[ER
]);
796 cl
= qfq_slot_head(grp
);
797 skb
= qdisc_dequeue_peeked(cl
->qdisc
);
799 WARN_ONCE(1, "qfq_dequeue: non-workconserving leaf\n");
804 qdisc_bstats_update(sch
, skb
);
807 len
= qdisc_pkt_len(skb
);
808 q
->V
+= (u64
)len
* IWSUM
;
809 pr_debug("qfq dequeue: len %u F %lld now %lld\n",
810 len
, (unsigned long long) cl
->F
, (unsigned long long) q
->V
);
812 if (qfq_update_class(grp
, cl
)) {
815 cl
= qfq_slot_scan(grp
);
817 __clear_bit(grp
->index
, &q
->bitmaps
[ER
]);
819 u64 roundedS
= qfq_round_down(cl
->S
, grp
->slot_shift
);
822 if (grp
->S
== roundedS
)
825 grp
->F
= roundedS
+ (2ULL << grp
->slot_shift
);
826 __clear_bit(grp
->index
, &q
->bitmaps
[ER
]);
827 s
= qfq_calc_state(q
, grp
);
828 __set_bit(grp
->index
, &q
->bitmaps
[s
]);
831 qfq_unblock_groups(q
, grp
->index
, old_F
);
835 qfq_update_eligible(q
, old_V
);
841 * Assign a reasonable start time for a new flow k in group i.
842 * Admissible values for \hat(F) are multiples of \sigma_i
843 * no greater than V+\sigma_i . Larger values mean that
844 * we had a wraparound so we consider the timestamp to be stale.
846 * If F is not stale and F >= V then we set S = F.
847 * Otherwise we should assign S = V, but this may violate
848 * the ordering in ER. So, if we have groups in ER, set S to
849 * the F_j of the first group j which would be blocking us.
850 * We are guaranteed not to move S backward because
851 * otherwise our group i would still be blocked.
853 static void qfq_update_start(struct qfq_sched
*q
, struct qfq_class
*cl
)
857 int slot_shift
= cl
->grp
->slot_shift
;
859 roundedF
= qfq_round_down(cl
->F
, slot_shift
);
860 limit
= qfq_round_down(q
->V
, slot_shift
) + (1ULL << slot_shift
);
862 if (!qfq_gt(cl
->F
, q
->V
) || qfq_gt(roundedF
, limit
)) {
863 /* timestamp was stale */
864 mask
= mask_from(q
->bitmaps
[ER
], cl
->grp
->index
);
866 struct qfq_group
*next
= qfq_ffs(q
, mask
);
867 if (qfq_gt(roundedF
, next
->F
)) {
873 } else /* timestamp is not stale */
877 static int qfq_enqueue(struct sk_buff
*skb
, struct Qdisc
*sch
)
879 struct qfq_sched
*q
= qdisc_priv(sch
);
880 struct qfq_class
*cl
;
883 cl
= qfq_classify(skb
, sch
, &err
);
885 if (err
& __NET_XMIT_BYPASS
)
890 pr_debug("qfq_enqueue: cl = %x\n", cl
->common
.classid
);
892 err
= qdisc_enqueue(skb
, cl
->qdisc
);
893 if (unlikely(err
!= NET_XMIT_SUCCESS
)) {
894 pr_debug("qfq_enqueue: enqueue failed %d\n", err
);
895 if (net_xmit_drop_count(err
)) {
902 bstats_update(&cl
->bstats
, skb
);
905 /* If the new skb is not the head of queue, then done here. */
906 if (cl
->qdisc
->q
.qlen
!= 1)
909 /* If reach this point, queue q was idle */
910 qfq_activate_class(q
, cl
, qdisc_pkt_len(skb
));
916 * Handle class switch from idle to backlogged.
918 static void qfq_activate_class(struct qfq_sched
*q
, struct qfq_class
*cl
,
919 unsigned int pkt_len
)
921 struct qfq_group
*grp
= cl
->grp
;
925 qfq_update_start(q
, cl
);
927 /* compute new finish time and rounded start. */
928 cl
->F
= cl
->S
+ (u64
)pkt_len
* cl
->inv_w
;
929 roundedS
= qfq_round_down(cl
->S
, grp
->slot_shift
);
932 * insert cl in the correct bucket.
933 * If cl->S >= grp->S we don't need to adjust the
934 * bucket list and simply go to the insertion phase.
935 * Otherwise grp->S is decreasing, we must make room
936 * in the bucket list, and also recompute the group state.
937 * Finally, if there were no flows in this group and nobody
938 * was in ER make sure to adjust V.
940 if (grp
->full_slots
) {
941 if (!qfq_gt(grp
->S
, cl
->S
))
944 /* create a slot for this cl->S */
945 qfq_slot_rotate(grp
, roundedS
);
946 /* group was surely ineligible, remove */
947 __clear_bit(grp
->index
, &q
->bitmaps
[IR
]);
948 __clear_bit(grp
->index
, &q
->bitmaps
[IB
]);
949 } else if (!q
->bitmaps
[ER
] && qfq_gt(roundedS
, q
->V
))
953 grp
->F
= roundedS
+ (2ULL << grp
->slot_shift
);
954 s
= qfq_calc_state(q
, grp
);
955 __set_bit(grp
->index
, &q
->bitmaps
[s
]);
957 pr_debug("qfq enqueue: new state %d %#lx S %lld F %lld V %lld\n",
959 (unsigned long long) cl
->S
,
960 (unsigned long long) cl
->F
,
961 (unsigned long long) q
->V
);
964 qfq_slot_insert(grp
, cl
, roundedS
);
968 static void qfq_slot_remove(struct qfq_sched
*q
, struct qfq_group
*grp
,
969 struct qfq_class
*cl
)
971 unsigned int i
, offset
;
974 roundedS
= qfq_round_down(cl
->S
, grp
->slot_shift
);
975 offset
= (roundedS
- grp
->S
) >> grp
->slot_shift
;
976 i
= (grp
->front
+ offset
) % QFQ_MAX_SLOTS
;
978 hlist_del(&cl
->next
);
979 if (hlist_empty(&grp
->slots
[i
]))
980 __clear_bit(offset
, &grp
->full_slots
);
984 * called to forcibly destroy a queue.
985 * If the queue is not in the front bucket, or if it has
986 * other queues in the front bucket, we can simply remove
987 * the queue with no other side effects.
988 * Otherwise we must propagate the event up.
990 static void qfq_deactivate_class(struct qfq_sched
*q
, struct qfq_class
*cl
)
992 struct qfq_group
*grp
= cl
->grp
;
998 qfq_slot_remove(q
, grp
, cl
);
1000 if (!grp
->full_slots
) {
1001 __clear_bit(grp
->index
, &q
->bitmaps
[IR
]);
1002 __clear_bit(grp
->index
, &q
->bitmaps
[EB
]);
1003 __clear_bit(grp
->index
, &q
->bitmaps
[IB
]);
1005 if (test_bit(grp
->index
, &q
->bitmaps
[ER
]) &&
1006 !(q
->bitmaps
[ER
] & ~((1UL << grp
->index
) - 1))) {
1007 mask
= q
->bitmaps
[ER
] & ((1UL << grp
->index
) - 1);
1009 mask
= ~((1UL << __fls(mask
)) - 1);
1012 qfq_move_groups(q
, mask
, EB
, ER
);
1013 qfq_move_groups(q
, mask
, IB
, IR
);
1015 __clear_bit(grp
->index
, &q
->bitmaps
[ER
]);
1016 } else if (hlist_empty(&grp
->slots
[grp
->front
])) {
1017 cl
= qfq_slot_scan(grp
);
1018 roundedS
= qfq_round_down(cl
->S
, grp
->slot_shift
);
1019 if (grp
->S
!= roundedS
) {
1020 __clear_bit(grp
->index
, &q
->bitmaps
[ER
]);
1021 __clear_bit(grp
->index
, &q
->bitmaps
[IR
]);
1022 __clear_bit(grp
->index
, &q
->bitmaps
[EB
]);
1023 __clear_bit(grp
->index
, &q
->bitmaps
[IB
]);
1025 grp
->F
= roundedS
+ (2ULL << grp
->slot_shift
);
1026 s
= qfq_calc_state(q
, grp
);
1027 __set_bit(grp
->index
, &q
->bitmaps
[s
]);
1031 qfq_update_eligible(q
, q
->V
);
1034 static void qfq_qlen_notify(struct Qdisc
*sch
, unsigned long arg
)
1036 struct qfq_sched
*q
= qdisc_priv(sch
);
1037 struct qfq_class
*cl
= (struct qfq_class
*)arg
;
1039 if (cl
->qdisc
->q
.qlen
== 0)
1040 qfq_deactivate_class(q
, cl
);
1043 static unsigned int qfq_drop(struct Qdisc
*sch
)
1045 struct qfq_sched
*q
= qdisc_priv(sch
);
1046 struct qfq_group
*grp
;
1047 unsigned int i
, j
, len
;
1049 for (i
= 0; i
<= QFQ_MAX_INDEX
; i
++) {
1050 grp
= &q
->groups
[i
];
1051 for (j
= 0; j
< QFQ_MAX_SLOTS
; j
++) {
1052 struct qfq_class
*cl
;
1053 struct hlist_node
*n
;
1055 hlist_for_each_entry(cl
, n
, &grp
->slots
[j
], next
) {
1057 if (!cl
->qdisc
->ops
->drop
)
1060 len
= cl
->qdisc
->ops
->drop(cl
->qdisc
);
1063 if (!cl
->qdisc
->q
.qlen
)
1064 qfq_deactivate_class(q
, cl
);
1075 static int qfq_init_qdisc(struct Qdisc
*sch
, struct nlattr
*opt
)
1077 struct qfq_sched
*q
= qdisc_priv(sch
);
1078 struct qfq_group
*grp
;
1081 err
= qdisc_class_hash_init(&q
->clhash
);
1085 for (i
= 0; i
<= QFQ_MAX_INDEX
; i
++) {
1086 grp
= &q
->groups
[i
];
1088 grp
->slot_shift
= QFQ_MTU_SHIFT
+ FRAC_BITS
1089 - (QFQ_MAX_INDEX
- i
);
1090 for (j
= 0; j
< QFQ_MAX_SLOTS
; j
++)
1091 INIT_HLIST_HEAD(&grp
->slots
[j
]);
1097 static void qfq_reset_qdisc(struct Qdisc
*sch
)
1099 struct qfq_sched
*q
= qdisc_priv(sch
);
1100 struct qfq_group
*grp
;
1101 struct qfq_class
*cl
;
1102 struct hlist_node
*n
, *tmp
;
1105 for (i
= 0; i
<= QFQ_MAX_INDEX
; i
++) {
1106 grp
= &q
->groups
[i
];
1107 for (j
= 0; j
< QFQ_MAX_SLOTS
; j
++) {
1108 hlist_for_each_entry_safe(cl
, n
, tmp
,
1109 &grp
->slots
[j
], next
) {
1110 qfq_deactivate_class(q
, cl
);
1115 for (i
= 0; i
< q
->clhash
.hashsize
; i
++) {
1116 hlist_for_each_entry(cl
, n
, &q
->clhash
.hash
[i
], common
.hnode
)
1117 qdisc_reset(cl
->qdisc
);
1122 static void qfq_destroy_qdisc(struct Qdisc
*sch
)
1124 struct qfq_sched
*q
= qdisc_priv(sch
);
1125 struct qfq_class
*cl
;
1126 struct hlist_node
*n
, *next
;
1129 tcf_destroy_chain(&q
->filter_list
);
1131 for (i
= 0; i
< q
->clhash
.hashsize
; i
++) {
1132 hlist_for_each_entry_safe(cl
, n
, next
, &q
->clhash
.hash
[i
],
1134 qfq_destroy_class(sch
, cl
);
1137 qdisc_class_hash_destroy(&q
->clhash
);
1140 static const struct Qdisc_class_ops qfq_class_ops
= {
1141 .change
= qfq_change_class
,
1142 .delete = qfq_delete_class
,
1143 .get
= qfq_get_class
,
1144 .put
= qfq_put_class
,
1145 .tcf_chain
= qfq_tcf_chain
,
1146 .bind_tcf
= qfq_bind_tcf
,
1147 .unbind_tcf
= qfq_unbind_tcf
,
1148 .graft
= qfq_graft_class
,
1149 .leaf
= qfq_class_leaf
,
1150 .qlen_notify
= qfq_qlen_notify
,
1151 .dump
= qfq_dump_class
,
1152 .dump_stats
= qfq_dump_class_stats
,
1156 static struct Qdisc_ops qfq_qdisc_ops __read_mostly
= {
1157 .cl_ops
= &qfq_class_ops
,
1159 .priv_size
= sizeof(struct qfq_sched
),
1160 .enqueue
= qfq_enqueue
,
1161 .dequeue
= qfq_dequeue
,
1162 .peek
= qdisc_peek_dequeued
,
1164 .init
= qfq_init_qdisc
,
1165 .reset
= qfq_reset_qdisc
,
1166 .destroy
= qfq_destroy_qdisc
,
1167 .owner
= THIS_MODULE
,
1170 static int __init
qfq_init(void)
1172 return register_qdisc(&qfq_qdisc_ops
);
1175 static void __exit
qfq_exit(void)
1177 unregister_qdisc(&qfq_qdisc_ops
);
1180 module_init(qfq_init
);
1181 module_exit(qfq_exit
);
1182 MODULE_LICENSE("GPL");