[PATCH] pkt_sched: QFQ Plus: fair-queueing service at DRR cost

From: Paolo Valente
Date: Thu Nov 22 2012 - 13:51:32 EST

This patch turns QFQ into QFQ+, a variant of QFQ that provides the
following two benefits: 1) QFQ+ is faster than QFQ, 2) differently
from QFQ, QFQ+ correctly schedules also non-leaves classes in a
hierarchical setting. A detailed description of QFQ+, plus a
performance comparison with DRR and QFQ, can be found in [1].

[1] P. Valente, "Reducing the Execution Time of Fair-Queueing Schedulers"
http://algo.ing.unimo.it/people/paolo/agg-sched/agg-sched.pdf

Signed-off-by: Paolo Valente <paolo.valente@xxxxxxxxxx>
---
net/sched/sch_qfq.c | 833 +++++++++++++++++++++++++++++++++++----------------
1 file changed, 569 insertions(+), 264 deletions(-)

diff --git a/net/sched/sch_qfq.c b/net/sched/sch_qfq.c
index 9687fa1..f2602b9 100644
--- a/net/sched/sch_qfq.c
+++ b/net/sched/sch_qfq.c
@@ -1,7 +1,8 @@
/*
- * net/sched/sch_qfq.c Quick Fair Queueing Scheduler.
+ * net/sched/sch_qfq.c Quick Fair Queueing Plus Scheduler.
*
* Copyright (c) 2009 Fabio Checconi, Luigi Rizzo, and Paolo Valente.
+ * Copyright (c) 2012 Paolo Valente.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
@@ -19,12 +20,18 @@
#include <net/pkt_cls.h>


-/* Quick Fair Queueing
- ===================
+/* Quick Fair Queueing Plus
+ ========================

Sources:

- Fabio Checconi, Luigi Rizzo, and Paolo Valente: "QFQ: Efficient
+ [1] Paolo Valente,
+ "Reducing the Execution Time of Fair-Queueing Schedulers."
+ http://algo.ing.unimo.it/people/paolo/agg-sched/agg-sched.pdf
+
+ Sources for QFQ:
+
+ [2] Fabio Checconi, Luigi Rizzo, and Paolo Valente: "QFQ: Efficient
Packet Scheduling with Tight Bandwidth Distribution Guarantees."

See also:
@@ -33,6 +40,20 @@

/*

+ QFQ+ divides classes into aggregates of at most MAX_AGG_CLASSES
+ classes. Each aggregate is timestamped with a virtual start time S
+ and a virtual finish time F, and scheduled according to its
+ timestamps. S and F are computed as a function of a system virtual
+ time function V. The classes within each aggregate are instead
+ scheduled with DRR.
+
+ To speed up operations, QFQ+ divides also aggregates into a limited
+ number of groups. Which group a class belongs to depends on the
+ ratio between the maximum packet length for the class and the weight
+ of the class. Groups have their own S and F. In the end, QFQ+
+ schedules groups, then aggregates within groups, then classes within
+ aggregates. See [1] and [2] for a full description.
+
Virtual time computations.

S, F and V are all computed in fixed point arithmetic with
@@ -76,27 +97,28 @@
#define QFQ_MAX_SLOTS 32

/*
- * Shifts used for class<->group mapping. We allow class weights that are
- * in the range [1, 2^MAX_WSHIFT], and we try to map each class i to the
+ * Shifts used for aggregate<->group mapping. We allow class weights that are
+ * in the range [1, 2^MAX_WSHIFT], and we try to map each aggregate i to the
* group with the smallest index that can support the L_i / r_i configured
- * for the class.
+ * for the classes in the aggregate.
*
* grp->index is the index of the group; and grp->slot_shift
* is the shift for the corresponding (scaled) sigma_i.
*/
#define QFQ_MAX_INDEX 24
-#define QFQ_MAX_WSHIFT 12
+#define QFQ_MAX_WSHIFT 10

-#define QFQ_MAX_WEIGHT (1<<QFQ_MAX_WSHIFT)
-#define QFQ_MAX_WSUM (16*QFQ_MAX_WEIGHT)
+#define QFQ_MAX_WEIGHT (1<<QFQ_MAX_WSHIFT) /* see qfq_slot_insert */
+#define QFQ_MAX_WSUM (64*QFQ_MAX_WEIGHT)

#define FRAC_BITS 30 /* fixed point arithmetic */
#define ONE_FP (1UL << FRAC_BITS)
#define IWSUM (ONE_FP/QFQ_MAX_WSUM)

#define QFQ_MTU_SHIFT 16 /* to support TSO/GSO */
-#define QFQ_MIN_SLOT_SHIFT (FRAC_BITS + QFQ_MTU_SHIFT - QFQ_MAX_INDEX)
-#define QFQ_MIN_LMAX 256 /* min possible lmax for a class */
+#define QFQ_MIN_LMAX 512 /* see qfq_slot_insert */
+
+#define QFQ_MAX_AGG_CLASSES 8 /* max num classes per aggregate allowed */

/*
* Possible group states. These values are used as indexes for the bitmaps
@@ -106,6 +128,8 @@ enum qfq_state { ER, IR, EB, IB, QFQ_MAX_STATE };

struct qfq_group;

+struct qfq_aggregate;
+
struct qfq_class {
struct Qdisc_class_common common;

@@ -116,7 +140,15 @@ struct qfq_class {
struct gnet_stats_queue qstats;
struct gnet_stats_rate_est rate_est;
struct Qdisc *qdisc;
+ struct list_head alist; /* Link for active-classes list. */
+ struct qfq_aggregate *agg; /* Parent aggregate. */
+ int deficit; /* DRR deficit counter. */
+};

+/*
+
+ */
+struct qfq_aggregate {
struct hlist_node next; /* Link for the slot list. */
u64 S, F; /* flow timestamps (exact) */

@@ -127,8 +159,18 @@ struct qfq_class {
struct qfq_group *grp;

/* these are copied from the flowset. */
- u32 inv_w; /* ONE_FP/weight */
- u32 lmax; /* Max packet size for this flow. */
+ u32 class_weight; /* Weight of each class in this aggregate. */
+ /* Max pkt size for the classes in this aggregate, DRR quantum. */
+ int lmax;
+
+ u32 inv_w; /* ONE_FP/(sum of weights of classes in aggr.). */
+ u32 budgetmax; /* Max budget for this aggregate. */
+ u32 initial_budget, budget; /* Initial and current budget. */
+
+ int num_classes; /* Number of classes in this aggr. */
+ struct list_head active; /* DRR queue of active classes. */
+
+ struct hlist_node nonfull_next; /* See nonfull_aggs in qfq_sched. */
};

struct qfq_group {
@@ -138,7 +180,7 @@ struct qfq_group {
unsigned int front; /* Index of the front slot. */
unsigned long full_slots; /* non-empty slots */

- /* Array of RR lists of active classes. */
+ /* Array of RR lists of active aggregates. */
struct hlist_head slots[QFQ_MAX_SLOTS];
};

@@ -146,13 +188,28 @@ struct qfq_sched {
struct tcf_proto *filter_list;
struct Qdisc_class_hash clhash;

- u64 V; /* Precise virtual time. */
- u32 wsum; /* weight sum */
+ u64 oldV, V; /* Precise virtual times. */
+ struct qfq_aggregate *in_serv_agg; /* Aggregate being served. */
+ u32 num_active_agg; /* Num. of active aggregates */
+ u32 wsum; /* weight sum */

unsigned long bitmaps[QFQ_MAX_STATE]; /* Group bitmaps. */
struct qfq_group groups[QFQ_MAX_INDEX + 1]; /* The groups. */
+ u32 min_slot_shift; /* Index of the group-0 bit in the bitmaps. */
+
+ u32 max_agg_classes; /* Max number of classes per aggr. */
+ struct hlist_head nonfull_aggs; /* Aggs with room for more classes. */
};

+/*
+ * Possible reasons why the timestamps of an aggregate are updated
+ * enqueue: the aggregate switches from idle to active and must scheduled
+ * for service
+ * requeue: the aggregate finishes its budget, so it stops being served and
+ * must be rescheduled for service
+ */
+enum update_reason {enqueue, requeue};
+
static struct qfq_class *qfq_find_class(struct Qdisc *sch, u32 classid)
{
struct qfq_sched *q = qdisc_priv(sch);
@@ -182,18 +239,18 @@ static const struct nla_policy qfq_policy[TCA_QFQ_MAX + 1] = {
* index = log_2(maxlen/weight) but we need to apply the scaling.
* This is used only once at flow creation.
*/
-static int qfq_calc_index(u32 inv_w, unsigned int maxlen)
+static int qfq_calc_index(u32 inv_w, unsigned int maxlen, u32 min_slot_shift)
{
u64 slot_size = (u64)maxlen * inv_w;
unsigned long size_map;
int index = 0;

- size_map = slot_size >> QFQ_MIN_SLOT_SHIFT;
+ size_map = slot_size >> min_slot_shift;
if (!size_map)
goto out;

index = __fls(size_map) + 1; /* basically a log_2 */
- index -= !(slot_size - (1ULL << (index + QFQ_MIN_SLOT_SHIFT - 1)));
+ index -= !(slot_size - (1ULL << (index + min_slot_shift - 1)));

if (index < 0)
index = 0;
@@ -204,66 +261,150 @@ out:
return index;
}

-/* Length of the next packet (0 if the queue is empty). */
-static unsigned int qdisc_peek_len(struct Qdisc *sch)
+static void qfq_deactivate_agg(struct qfq_sched *, struct qfq_aggregate *);
+static void qfq_activate_agg(struct qfq_sched *, struct qfq_aggregate *,
+ enum update_reason);
+
+static void qfq_init_agg(struct qfq_sched *q, struct qfq_aggregate *agg,
+ u32 lmax, u32 weight)
{
- struct sk_buff *skb;
+ INIT_LIST_HEAD(&agg->active);
+ hlist_add_head(&agg->nonfull_next, &q->nonfull_aggs);

- skb = sch->ops->peek(sch);
- return skb ? qdisc_pkt_len(skb) : 0;
+ agg->lmax = lmax;
+ agg->class_weight = weight;
}

-static void qfq_deactivate_class(struct qfq_sched *, struct qfq_class *);
-static void qfq_activate_class(struct qfq_sched *q, struct qfq_class *cl,
- unsigned int len);
+static struct qfq_aggregate *qfq_find_agg(struct qfq_sched *q,
+ u32 lmax, u32 weight)
+{
+ struct qfq_aggregate *agg;
+ struct hlist_node *n;

-static void qfq_update_class_params(struct qfq_sched *q, struct qfq_class *cl,
- u32 lmax, u32 inv_w, int delta_w)
+ hlist_for_each_entry(agg, n, &q->nonfull_aggs, nonfull_next)
+ if (agg->lmax == lmax && agg->class_weight == weight)
+ return agg;
+
+ return NULL;
+}
+
+
+/* Update aggregate as a function of the new number of classes. */
+static void qfq_update_agg(struct qfq_sched *q, struct qfq_aggregate *agg,
+ int new_num_classes)
{
- int i;
+ u32 new_agg_weight;
+
+ if (new_num_classes == q->max_agg_classes)
+ hlist_del_init(&agg->nonfull_next);

- /* update qfq-specific data */
- cl->lmax = lmax;
- cl->inv_w = inv_w;
- i = qfq_calc_index(cl->inv_w, cl->lmax);
+ if (agg->num_classes > new_num_classes &&
+ new_num_classes == q->max_agg_classes - 1) /* agg no more full */
+ hlist_add_head(&agg->nonfull_next, &q->nonfull_aggs);

- cl->grp = &q->groups[i];
+ agg->budgetmax = new_num_classes * agg->lmax;
+ new_agg_weight = agg->class_weight * new_num_classes;
+ agg->inv_w = ONE_FP/new_agg_weight;

- q->wsum += delta_w;
+ if (agg->grp == NULL) {
+ int i = qfq_calc_index(agg->inv_w, agg->budgetmax,
+ q->min_slot_shift);
+ agg->grp = &q->groups[i];
+ }
+
+ q->wsum +=
+ (int) agg->class_weight * (new_num_classes - agg->num_classes);
+
+ agg->num_classes = new_num_classes;
}

-static void qfq_update_reactivate_class(struct qfq_sched *q,
- struct qfq_class *cl,
- u32 inv_w, u32 lmax, int delta_w)
+/* Add class to aggregate. */
+static void qfq_add_to_agg(struct qfq_sched *q,
+ struct qfq_aggregate *agg,
+ struct qfq_class *cl)
{
- bool need_reactivation = false;
- int i = qfq_calc_index(inv_w, lmax);
+ cl->agg = agg;
+
+ qfq_update_agg(q, agg, agg->num_classes+1);
+ if (cl->qdisc->q.qlen > 0) { /* adding an active class */
+ list_add_tail(&cl->alist, &agg->active);
+ if (list_first_entry(&agg->active, struct qfq_class, alist) ==
+ cl && q->in_serv_agg != agg) /* agg was inactive */
+ qfq_activate_agg(q, agg, enqueue); /* schedule agg */
+ }
+}

- if (&q->groups[i] != cl->grp && cl->qdisc->q.qlen > 0) {
- /*
- * shift cl->F back, to not charge the
- * class for the not-yet-served head
- * packet
- */
- cl->F = cl->S;
- /* remove class from its slot in the old group */
- qfq_deactivate_class(q, cl);
- need_reactivation = true;
+static struct qfq_aggregate *qfq_choose_next_agg(struct qfq_sched *);
+
+static void qfq_destroy_agg(struct qfq_sched *q, struct qfq_aggregate *agg)
+{
+ if (!hlist_unhashed(&agg->nonfull_next))
+ hlist_del_init(&agg->nonfull_next);
+ if (q->in_serv_agg == agg)
+ q->in_serv_agg = qfq_choose_next_agg(q);
+ kfree(agg);
+}
+
+/* Deschedule class from within its parent aggregate. */
+static void qfq_deactivate_class(struct qfq_sched *q, struct qfq_class *cl)
+{
+ struct qfq_aggregate *agg = cl->agg;
+
+
+ list_del(&cl->alist); /* remove from RR queue of the aggregate */
+ if (list_empty(&agg->active)) /* agg is now inactive */
+ qfq_deactivate_agg(q, agg);
+}
+
+/* Remove class from its parent aggregate. */
+static void qfq_rm_from_agg(struct qfq_sched *q, struct qfq_class *cl)
+{
+ struct qfq_aggregate *agg = cl->agg;
+
+ cl->agg = NULL;
+ if (agg->num_classes == 1) { /* agg being emptied, destroy it */
+ qfq_destroy_agg(q, agg);
+ return;
}
+ qfq_update_agg(q, agg, agg->num_classes-1);
+}

- qfq_update_class_params(q, cl, lmax, inv_w, delta_w);
+/* Deschedule class and remove it from its parent aggregate. */
+static void qfq_deact_rm_from_agg(struct qfq_sched *q, struct qfq_class *cl)
+{
+ if (cl->qdisc->q.qlen > 0) /* class is active */
+ qfq_deactivate_class(q, cl);

- if (need_reactivation) /* activate in new group */
- qfq_activate_class(q, cl, qdisc_peek_len(cl->qdisc));
+ qfq_rm_from_agg(q, cl);
}

+/* Move class to a new aggregate, matching the new class weight and/or lmax */
+static int qfq_change_agg(struct Qdisc *sch, struct qfq_class *cl, u32 weight,
+ u32 lmax)
+{
+ struct qfq_sched *q = qdisc_priv(sch);
+ struct qfq_aggregate *new_agg = qfq_find_agg(q, lmax, weight);
+
+ if (new_agg == NULL) { /* create new aggregate */
+ new_agg = kzalloc(sizeof(*new_agg), GFP_ATOMIC);
+ if (new_agg == NULL)
+ return -ENOBUFS;
+ qfq_init_agg(q, new_agg, lmax, weight);
+ }
+ qfq_deact_rm_from_agg(q, cl);
+ qfq_add_to_agg(q, new_agg, cl);
+
+ return 0;
+}

static int qfq_change_class(struct Qdisc *sch, u32 classid, u32 parentid,
struct nlattr **tca, unsigned long *arg)
{
struct qfq_sched *q = qdisc_priv(sch);
struct qfq_class *cl = (struct qfq_class *)*arg;
+ bool existing = false;
struct nlattr *tb[TCA_QFQ_MAX + 1];
+ struct qfq_aggregate *new_agg = NULL;
u32 weight, lmax, inv_w;
int err;
int delta_w;
@@ -286,15 +427,6 @@ static int qfq_change_class(struct Qdisc *sch, u32 classid, u32 parentid,
} else
weight = 1;

- inv_w = ONE_FP / weight;
- weight = ONE_FP / inv_w;
- delta_w = weight - (cl ? ONE_FP / cl->inv_w : 0);
- if (q->wsum + delta_w > QFQ_MAX_WSUM) {
- pr_notice("qfq: total weight out of range (%u + %u)\n",
- delta_w, q->wsum);
- return -EINVAL;
- }
-
if (tb[TCA_QFQ_LMAX]) {
lmax = nla_get_u32(tb[TCA_QFQ_LMAX]);
if (lmax < QFQ_MIN_LMAX || lmax > (1UL << QFQ_MTU_SHIFT)) {
@@ -304,7 +436,23 @@ static int qfq_change_class(struct Qdisc *sch, u32 classid, u32 parentid,
} else
lmax = psched_mtu(qdisc_dev(sch));

- if (cl != NULL) {
+ inv_w = ONE_FP / weight;
+ weight = ONE_FP / inv_w;
+
+ if (cl != NULL &&
+ lmax == cl->agg->lmax &&
+ weight == cl->agg->class_weight)
+ return 0; /* nothing to change */
+
+ delta_w = weight - (cl ? cl->agg->class_weight : 0);
+
+ if (q->wsum + delta_w > QFQ_MAX_WSUM) {
+ pr_notice("qfq: total weight out of range (%d + %u)\n",
+ delta_w, q->wsum);
+ return -EINVAL;
+ }
+
+ if (cl != NULL) { /* modify existing class */
if (tca[TCA_RATE]) {
err = gen_replace_estimator(&cl->bstats, &cl->rate_est,
qdisc_root_sleeping_lock(sch),
@@ -312,25 +460,18 @@ static int qfq_change_class(struct Qdisc *sch, u32 classid, u32 parentid,
if (err)
return err;
}
-
- if (lmax == cl->lmax && inv_w == cl->inv_w)
- return 0; /* nothing to update */
-
- sch_tree_lock(sch);
- qfq_update_reactivate_class(q, cl, inv_w, lmax, delta_w);
- sch_tree_unlock(sch);
-
- return 0;
+ existing = true;
+ goto set_change_agg;
}

+ /* create and init new class */
cl = kzalloc(sizeof(struct qfq_class), GFP_KERNEL);
if (cl == NULL)
return -ENOBUFS;

cl->refcnt = 1;
cl->common.classid = classid;
-
- qfq_update_class_params(q, cl, lmax, inv_w, delta_w);
+ cl->deficit = lmax;

cl->qdisc = qdisc_create_dflt(sch->dev_queue,
&pfifo_qdisc_ops, classid);
@@ -341,11 +482,8 @@ static int qfq_change_class(struct Qdisc *sch, u32 classid, u32 parentid,
err = gen_new_estimator(&cl->bstats, &cl->rate_est,
qdisc_root_sleeping_lock(sch),
tca[TCA_RATE]);
- if (err) {
- qdisc_destroy(cl->qdisc);
- kfree(cl);
- return err;
- }
+ if (err)
+ goto destroy_class;
}

sch_tree_lock(sch);
@@ -354,19 +492,39 @@ static int qfq_change_class(struct Qdisc *sch, u32 classid, u32 parentid,

qdisc_class_hash_grow(sch, &q->clhash);

+set_change_agg:
+ sch_tree_lock(sch);
+ new_agg = qfq_find_agg(q, lmax, weight);
+ if (new_agg == NULL) { /* create new aggregate */
+ sch_tree_unlock(sch);
+ new_agg = kzalloc(sizeof(*new_agg), GFP_KERNEL);
+ if (new_agg == NULL) {
+ err = -ENOBUFS;
+ gen_kill_estimator(&cl->bstats, &cl->rate_est);
+ goto destroy_class;
+ }
+ sch_tree_lock(sch);
+ qfq_init_agg(q, new_agg, lmax, weight);
+ }
+ if (existing)
+ qfq_deact_rm_from_agg(q, cl);
+ qfq_add_to_agg(q, new_agg, cl);
+ sch_tree_unlock(sch);
+
*arg = (unsigned long)cl;
return 0;
+
+destroy_class:
+ qdisc_destroy(cl->qdisc);
+ kfree(cl);
+ return err;
}

static void qfq_destroy_class(struct Qdisc *sch, struct qfq_class *cl)
{
struct qfq_sched *q = qdisc_priv(sch);

- if (cl->inv_w) {
- q->wsum -= ONE_FP / cl->inv_w;
- cl->inv_w = 0;
- }
-
+ qfq_rm_from_agg(q, cl);
gen_kill_estimator(&cl->bstats, &cl->rate_est);
qdisc_destroy(cl->qdisc);
kfree(cl);
@@ -481,8 +639,8 @@ static int qfq_dump_class(struct Qdisc *sch, unsigned long arg,
nest = nla_nest_start(skb, TCA_OPTIONS);
if (nest == NULL)
goto nla_put_failure;
- if (nla_put_u32(skb, TCA_QFQ_WEIGHT, ONE_FP/cl->inv_w) ||
- nla_put_u32(skb, TCA_QFQ_LMAX, cl->lmax))
+ if (nla_put_u32(skb, TCA_QFQ_WEIGHT, cl->agg->class_weight) ||
+ nla_put_u32(skb, TCA_QFQ_LMAX, cl->agg->lmax))
goto nla_put_failure;
return nla_nest_end(skb, nest);

@@ -500,8 +658,8 @@ static int qfq_dump_class_stats(struct Qdisc *sch, unsigned long arg,
memset(&xstats, 0, sizeof(xstats));
cl->qdisc->qstats.qlen = cl->qdisc->q.qlen;

- xstats.weight = ONE_FP/cl->inv_w;
- xstats.lmax = cl->lmax;
+ xstats.weight = cl->agg->class_weight;
+ xstats.lmax = cl->agg->lmax;

if (gnet_stats_copy_basic(d, &cl->bstats) < 0 ||
gnet_stats_copy_rate_est(d, &cl->bstats, &cl->rate_est) < 0 ||
@@ -652,16 +810,16 @@ static void qfq_unblock_groups(struct qfq_sched *q, int index, u64 old_F)
* perhaps
*
old_V ^= q->V;
- old_V >>= QFQ_MIN_SLOT_SHIFT;
+ old_V >>= q->min_slot_shift;
if (old_V) {
...
}
*
*/
-static void qfq_make_eligible(struct qfq_sched *q, u64 old_V)
+static void qfq_make_eligible(struct qfq_sched *q)
{
- unsigned long vslot = q->V >> QFQ_MIN_SLOT_SHIFT;
- unsigned long old_vslot = old_V >> QFQ_MIN_SLOT_SHIFT;
+ unsigned long vslot = q->V >> q->min_slot_shift;
+ unsigned long old_vslot = q->oldV >> q->min_slot_shift;

if (vslot != old_vslot) {
unsigned long mask = (1UL << fls(vslot ^ old_vslot)) - 1;
@@ -672,34 +830,38 @@ static void qfq_make_eligible(struct qfq_sched *q, u64 old_V)


/*
- * If the weight and lmax (max_pkt_size) of the classes do not change,
- * then QFQ guarantees that the slot index is never higher than
- * 2 + ((1<<QFQ_MTU_SHIFT)/QFQ_MIN_LMAX) * (QFQ_MAX_WEIGHT/QFQ_MAX_WSUM).
+ * The index of the slot in which the aggregate is to be inserted must
+ * not be higher than QFQ_MAX_SLOTS-2. There is a '-2' and not a '-1'
+ * because the start time of the group may be moved backward by one
+ * slot after the aggregate has been inserted, and this would cause
+ * non-empty slots to be right-shifted by one position.
*
- * With the current values of the above constants, the index is
- * then guaranteed to never be higher than 2 + 256 * (1 / 16) = 18.
+ * If the weight and lmax (max_pkt_size) of the classes do not change,
+ * then QFQ+ does meet the above contraint according to the current
+ * values of its parameters. In fact, if the weight and lmax of the
+ * classes do not change, then, from the theory, QFQ+ guarantees that
+ * the slot index is never higher than
+ * 2 + QFQ_MAX_AGG_CLASSES * ((1<<QFQ_MTU_SHIFT)/QFQ_MIN_LMAX) *
+ * (QFQ_MAX_WEIGHT/QFQ_MAX_WSUM) = 2 + 8 * 128 * (1 / 64) = 18
*
* When the weight of a class is increased or the lmax of the class is
- * decreased, a new class with smaller slot size may happen to be
- * activated. The activation of this class should be properly delayed
- * to when the service of the class has finished in the ideal system
- * tracked by QFQ. If the activation of the class is not delayed to
- * this reference time instant, then this class may be unjustly served
- * before other classes waiting for service. This may cause
- * (unfrequently) the above bound to the slot index to be violated for
- * some of these unlucky classes.
+ * decreased, a new aggregate with smaller slot size than the original
+ * parent aggregate of the class may happen to be activated. The
+ * activation of this aggregate should be properly delayed to when the
+ * service of the class has finished in the ideal system tracked by
+ * QFQ+. If the activation of the aggregate is not delayed to this
+ * reference time instant, then this aggregate may be unjustly served
+ * before other aggregates waiting for service. This may cause the
+ * above bound to the slot index to be violated for some of these
+ * unlucky aggregates.
*
- * Instead of delaying the activation of the new class, which is quite
- * complex, the following inaccurate but simple solution is used: if
- * the slot index is higher than QFQ_MAX_SLOTS-2, then the timestamps
- * of the class are shifted backward so as to let the slot index
- * become equal to QFQ_MAX_SLOTS-2. This threshold is used because, if
- * the slot index is above it, then the data structure implementing
- * the bucket list either gets immediately corrupted or may get
- * corrupted on a possible next packet arrival that causes the start
- * time of the group to be shifted backward.
+ * Instead of delaying the activation of the new aggregate, which is
+ * quite complex, the following inaccurate but simple solution is used:
+ * if the slot index is higher than QFQ_MAX_SLOTS-2, then the
+ * timestamps of the aggregate are shifted backward so as to let the
+ * slot index become equal to QFQ_MAX_SLOTS-2.
*/
-static void qfq_slot_insert(struct qfq_group *grp, struct qfq_class *cl,
+static void qfq_slot_insert(struct qfq_group *grp, struct qfq_aggregate *agg,
u64 roundedS)
{
u64 slot = (roundedS - grp->S) >> grp->slot_shift;
@@ -708,22 +870,22 @@ static void qfq_slot_insert(struct qfq_group *grp, struct qfq_class *cl,
if (unlikely(slot > QFQ_MAX_SLOTS - 2)) {
u64 deltaS = roundedS - grp->S -
((u64)(QFQ_MAX_SLOTS - 2)<<grp->slot_shift);
- cl->S -= deltaS;
- cl->F -= deltaS;
+ agg->S -= deltaS;
+ agg->F -= deltaS;
slot = QFQ_MAX_SLOTS - 2;
}

i = (grp->front + slot) % QFQ_MAX_SLOTS;

- hlist_add_head(&cl->next, &grp->slots[i]);
+ hlist_add_head(&agg->next, &grp->slots[i]);
__set_bit(slot, &grp->full_slots);
}

/* Maybe introduce hlist_first_entry?? */
-static struct qfq_class *qfq_slot_head(struct qfq_group *grp)
+static struct qfq_aggregate *qfq_slot_head(struct qfq_group *grp)
{
return hlist_entry(grp->slots[grp->front].first,
- struct qfq_class, next);
+ struct qfq_aggregate, next);
}

/*
@@ -731,20 +893,20 @@ static struct qfq_class *qfq_slot_head(struct qfq_group *grp)
*/
static void qfq_front_slot_remove(struct qfq_group *grp)
{
- struct qfq_class *cl = qfq_slot_head(grp);
+ struct qfq_aggregate *agg = qfq_slot_head(grp);

- BUG_ON(!cl);
- hlist_del(&cl->next);
+ BUG_ON(!agg);
+ hlist_del(&agg->next);
if (hlist_empty(&grp->slots[grp->front]))
__clear_bit(0, &grp->full_slots);
}

/*
- * Returns the first full queue in a group. As a side effect,
- * adjust the bucket list so the first non-empty bucket is at
- * position 0 in full_slots.
+ * Returns the first aggregate in the first non-empty bucket of the
+ * group. As a side effect, adjusts the bucket list so the first
+ * non-empty bucket is at position 0 in full_slots.
*/
-static struct qfq_class *qfq_slot_scan(struct qfq_group *grp)
+static struct qfq_aggregate *qfq_slot_scan(struct qfq_group *grp)
{
unsigned int i;

@@ -780,7 +942,7 @@ static void qfq_slot_rotate(struct qfq_group *grp, u64 roundedS)
grp->front = (grp->front - i) % QFQ_MAX_SLOTS;
}

-static void qfq_update_eligible(struct qfq_sched *q, u64 old_V)
+static void qfq_update_eligible(struct qfq_sched *q)
{
struct qfq_group *grp;
unsigned long ineligible;
@@ -792,137 +954,226 @@ static void qfq_update_eligible(struct qfq_sched *q, u64 old_V)
if (qfq_gt(grp->S, q->V))
q->V = grp->S;
}
- qfq_make_eligible(q, old_V);
+ qfq_make_eligible(q);
}
}

-/*
- * Updates the class, returns true if also the group needs to be updated.
- */
-static bool qfq_update_class(struct qfq_group *grp, struct qfq_class *cl)
+/* Dequeue head packet of the head class in the DRR queue of the aggregate. */
+static void agg_dequeue(struct qfq_aggregate *agg,
+ struct qfq_class *cl, unsigned int len)
{
- unsigned int len = qdisc_peek_len(cl->qdisc);
-
- cl->S = cl->F;
- if (!len)
- qfq_front_slot_remove(grp); /* queue is empty */
- else {
- u64 roundedS;
+ qdisc_dequeue_peeked(cl->qdisc);

- cl->F = cl->S + (u64)len * cl->inv_w;
- roundedS = qfq_round_down(cl->S, grp->slot_shift);
- if (roundedS == grp->S)
- return false;
+ cl->deficit -= (int) len;

- qfq_front_slot_remove(grp);
- qfq_slot_insert(grp, cl, roundedS);
+ if (cl->qdisc->q.qlen == 0) /* no more packets, remove from list */
+ list_del(&cl->alist);
+ else if (cl->deficit < qdisc_pkt_len(cl->qdisc->ops->peek(cl->qdisc))) {
+ cl->deficit += agg->lmax;
+ list_move_tail(&cl->alist, &agg->active);
}
+}
+
+static inline struct sk_buff *qfq_peek_skb(struct qfq_aggregate *agg,
+ struct qfq_class **cl,
+ unsigned int *len)
+{
+ struct sk_buff *skb;
+
+ *cl = list_first_entry(&agg->active, struct qfq_class, alist);
+ skb = (*cl)->qdisc->ops->peek((*cl)->qdisc);
+ if (skb == NULL)
+ WARN_ONCE(1, "qfq_dequeue: non-workconserving leaf\n");
+ else
+ *len = qdisc_pkt_len(skb);
+
+ return skb;
+}
+
+/* Update F according to the actual service received by the aggregate. */
+static inline void charge_actual_service(struct qfq_aggregate *agg)
+{
+ /* compute the service received by the aggregate */
+ u32 service_received = agg->initial_budget - agg->budget;

- return true;
+ agg->F = agg->S + (u64)service_received * agg->inv_w;
}

static struct sk_buff *qfq_dequeue(struct Qdisc *sch)
{
struct qfq_sched *q = qdisc_priv(sch);
- struct qfq_group *grp;
+ struct qfq_aggregate *in_serv_agg = q->in_serv_agg;
struct qfq_class *cl;
- struct sk_buff *skb;
- unsigned int len;
- u64 old_V;
+ struct sk_buff *skb = NULL;
+ /* next-packet len, 0 means no more active classes in in-service agg */
+ unsigned int len = 0;

- if (!q->bitmaps[ER])
+ if (in_serv_agg == NULL)
return NULL;

- grp = qfq_ffs(q, q->bitmaps[ER]);
+ if (!list_empty(&in_serv_agg->active))
+ skb = qfq_peek_skb(in_serv_agg, &cl, &len);

- cl = qfq_slot_head(grp);
- skb = qdisc_dequeue_peeked(cl->qdisc);
- if (!skb) {
- WARN_ONCE(1, "qfq_dequeue: non-workconserving leaf\n");
- return NULL;
+ /*
+ * If there are no active classes in the in-service aggregate,
+ * or if the aggregate has not enough budget to serve its next
+ * class, then choose the next aggregate to serve.
+ */
+ if (len == 0 || in_serv_agg->budget < len) {
+ charge_actual_service(in_serv_agg);
+
+ /* recharge the budget of the aggregate */
+ in_serv_agg->initial_budget = in_serv_agg->budget =
+ in_serv_agg->budgetmax;
+
+ if (!list_empty(&in_serv_agg->active))
+ /*
+ * Still active: reschedule for
+ * service. Possible optimization: if no other
+ * aggregate is active, then there is no point
+ * in rescheduling this aggregate, and we can
+ * just keep it as the in-service one. This
+ * should be however a corner case, and to
+ * handle it, we would need to maintain an
+ * extra num_active_aggs field.
+ */
+ qfq_activate_agg(q, in_serv_agg, requeue);
+ else if (sch->q.qlen == 0) { /* no aggregate to serve */
+ q->in_serv_agg = NULL;
+ return NULL;
+ }
+
+ /*
+ * If we get here, there are other aggregates queued:
+ * choose the new aggregate to serve.
+ */
+ in_serv_agg = q->in_serv_agg = qfq_choose_next_agg(q);
+ skb = qfq_peek_skb(in_serv_agg, &cl, &len);
}
+ if (!skb)
+ return NULL;

sch->q.qlen--;
qdisc_bstats_update(sch, skb);

- old_V = q->V;
- len = qdisc_pkt_len(skb);
+ agg_dequeue(in_serv_agg, cl, len);
+ in_serv_agg->budget -= len;
q->V += (u64)len * IWSUM;
pr_debug("qfq dequeue: len %u F %lld now %lld\n",
- len, (unsigned long long) cl->F, (unsigned long long) q->V);
+ len, (unsigned long long) in_serv_agg->F,
+ (unsigned long long) q->V);

- if (qfq_update_class(grp, cl)) {
- u64 old_F = grp->F;
+ return skb;
+}

- cl = qfq_slot_scan(grp);
- if (!cl)
- __clear_bit(grp->index, &q->bitmaps[ER]);
- else {
- u64 roundedS = qfq_round_down(cl->S, grp->slot_shift);
- unsigned int s;
+static struct qfq_aggregate *qfq_choose_next_agg(struct qfq_sched *q)
+{
+ struct qfq_group *grp;
+ struct qfq_aggregate *agg, *new_front_agg;
+ u64 old_F;

- if (grp->S == roundedS)
- goto skip_unblock;
- grp->S = roundedS;
- grp->F = roundedS + (2ULL << grp->slot_shift);
- __clear_bit(grp->index, &q->bitmaps[ER]);
- s = qfq_calc_state(q, grp);
- __set_bit(grp->index, &q->bitmaps[s]);
- }
+ qfq_update_eligible(q);
+ q->oldV = q->V;
+
+ if (!q->bitmaps[ER])
+ return NULL;
+
+ grp = qfq_ffs(q, q->bitmaps[ER]);
+ old_F = grp->F;

- qfq_unblock_groups(q, grp->index, old_F);
+ agg = qfq_slot_head(grp);
+
+ /* agg starts to be served, remove it from schedule */
+ qfq_front_slot_remove(grp);
+
+ new_front_agg = qfq_slot_scan(grp);
+
+ if (new_front_agg == NULL) /* group is now inactive, remove from ER */
+ __clear_bit(grp->index, &q->bitmaps[ER]);
+ else {
+ u64 roundedS = qfq_round_down(new_front_agg->S,
+ grp->slot_shift);
+ unsigned int s;
+
+ if (grp->S == roundedS)
+ return agg;
+ grp->S = roundedS;
+ grp->F = roundedS + (2ULL << grp->slot_shift);
+ __clear_bit(grp->index, &q->bitmaps[ER]);
+ s = qfq_calc_state(q, grp);
+ __set_bit(grp->index, &q->bitmaps[s]);
}

-skip_unblock:
- qfq_update_eligible(q, old_V);
+ qfq_unblock_groups(q, grp->index, old_F);

- return skb;
+ return agg;
}

/*
- * Assign a reasonable start time for a new flow k in group i.
+ * Assign a reasonable start time for a new aggregate in group i.
* Admissible values for \hat(F) are multiples of \sigma_i
* no greater than V+\sigma_i . Larger values mean that
* we had a wraparound so we consider the timestamp to be stale.
*
* If F is not stale and F >= V then we set S = F.
* Otherwise we should assign S = V, but this may violate
- * the ordering in ER. So, if we have groups in ER, set S to
- * the F_j of the first group j which would be blocking us.
+ * the ordering in EB (see [2]). So, if we have groups in ER,
+ * set S to the F_j of the first group j which would be blocking us.
* We are guaranteed not to move S backward because
* otherwise our group i would still be blocked.
*/
-static void qfq_update_start(struct qfq_sched *q, struct qfq_class *cl)
+static void qfq_update_start(struct qfq_sched *q, struct qfq_aggregate *agg)
{
unsigned long mask;
u64 limit, roundedF;
- int slot_shift = cl->grp->slot_shift;
+ int slot_shift = agg->grp->slot_shift;

- roundedF = qfq_round_down(cl->F, slot_shift);
+ roundedF = qfq_round_down(agg->F, slot_shift);
limit = qfq_round_down(q->V, slot_shift) + (1ULL << slot_shift);

- if (!qfq_gt(cl->F, q->V) || qfq_gt(roundedF, limit)) {
+ if (!qfq_gt(agg->F, q->V) || qfq_gt(roundedF, limit)) {
/* timestamp was stale */
- mask = mask_from(q->bitmaps[ER], cl->grp->index);
+ mask = mask_from(q->bitmaps[ER], agg->grp->index);
if (mask) {
struct qfq_group *next = qfq_ffs(q, mask);
if (qfq_gt(roundedF, next->F)) {
if (qfq_gt(limit, next->F))
- cl->S = next->F;
+ agg->S = next->F;
else /* preserve timestamp correctness */
- cl->S = limit;
+ agg->S = limit;
return;
}
}
- cl->S = q->V;
+ agg->S = q->V;
} else /* timestamp is not stale */
- cl->S = cl->F;
+ agg->S = agg->F;
+}
+
+/*
+ * Update the timestamps of agg before scheduling/rescheduling it for
+ * service. In particular, assign to agg->F its maximum possible
+ * value, i.e., the virtual finish time with which the aggregate
+ * should be labeled if it used all its budget once in service.
+ */
+static inline void
+qfq_update_agg_ts(struct qfq_sched *q,
+ struct qfq_aggregate *agg, enum update_reason reason)
+{
+ if (reason != requeue)
+ qfq_update_start(q, agg);
+ else /* just charge agg for the service received */
+ agg->S = agg->F;
+
+ agg->F = agg->S + (u64)agg->budgetmax * agg->inv_w;
}

+static void qfq_schedule_agg(struct qfq_sched *, struct qfq_aggregate *);
+
static int qfq_enqueue(struct sk_buff *skb, struct Qdisc *sch)
{
struct qfq_sched *q = qdisc_priv(sch);
struct qfq_class *cl;
+ struct qfq_aggregate *agg;
int err = 0;

cl = qfq_classify(skb, sch, &err);
@@ -934,11 +1185,13 @@ static int qfq_enqueue(struct sk_buff *skb, struct Qdisc *sch)
}
pr_debug("qfq_enqueue: cl = %x\n", cl->common.classid);

- if (unlikely(cl->lmax < qdisc_pkt_len(skb))) {
+ if (unlikely(cl->agg->lmax < qdisc_pkt_len(skb))) {
pr_debug("qfq: increasing maxpkt from %u to %u for class %u",
- cl->lmax, qdisc_pkt_len(skb), cl->common.classid);
- qfq_update_reactivate_class(q, cl, cl->inv_w,
- qdisc_pkt_len(skb), 0);
+ cl->agg->lmax, qdisc_pkt_len(skb), cl->common.classid);
+ err = qfq_change_agg(sch, cl, cl->agg->class_weight,
+ qdisc_pkt_len(skb));
+ if (err)
+ return err;
}

err = qdisc_enqueue(skb, cl->qdisc);
@@ -954,35 +1207,50 @@ static int qfq_enqueue(struct sk_buff *skb, struct Qdisc *sch)
bstats_update(&cl->bstats, skb);
++sch->q.qlen;

- /* If the new skb is not the head of queue, then done here. */
- if (cl->qdisc->q.qlen != 1)
+ agg = cl->agg;
+ /* if the queue was not empty, then done here */
+ if (cl->qdisc->q.qlen != 1) {
+ if (unlikely(skb == cl->qdisc->ops->peek(cl->qdisc)) &&
+ list_first_entry(&agg->active, struct qfq_class, alist)
+ == cl && cl->deficit < qdisc_pkt_len(skb))
+ list_move_tail(&cl->alist, &agg->active);
+
return err;
+ }
+
+ /* schedule class for service within the aggregate */
+ cl->deficit = agg->lmax;
+ list_add_tail(&cl->alist, &agg->active);
+
+ if (list_first_entry(&agg->active, struct qfq_class, alist) != cl)
+ return err; /* aggregate was not empty, nothing else to do */
+
+ /* recharge budget */
+ agg->initial_budget = agg->budget = agg->budgetmax;

- /* If reach this point, queue q was idle */
- qfq_activate_class(q, cl, qdisc_pkt_len(skb));
+ qfq_update_agg_ts(q, agg, enqueue);
+ if (q->in_serv_agg == NULL)
+ q->in_serv_agg = agg;
+ else if (agg != q->in_serv_agg)
+ qfq_schedule_agg(q, agg);

return err;
}

/*
- * Handle class switch from idle to backlogged.
+ * Schedule aggregate according to its timestamps.
*/
-static void qfq_activate_class(struct qfq_sched *q, struct qfq_class *cl,
- unsigned int pkt_len)
+static void qfq_schedule_agg(struct qfq_sched *q, struct qfq_aggregate *agg)
{
- struct qfq_group *grp = cl->grp;
+ struct qfq_group *grp = agg->grp;
u64 roundedS;
int s;

- qfq_update_start(q, cl);
-
- /* compute new finish time and rounded start. */
- cl->F = cl->S + (u64)pkt_len * cl->inv_w;
- roundedS = qfq_round_down(cl->S, grp->slot_shift);
+ roundedS = qfq_round_down(agg->S, grp->slot_shift);

/*
- * insert cl in the correct bucket.
- * If cl->S >= grp->S we don't need to adjust the
+ * Insert agg in the correct bucket.
+ * If agg->S >= grp->S we don't need to adjust the
* bucket list and simply go to the insertion phase.
* Otherwise grp->S is decreasing, we must make room
* in the bucket list, and also recompute the group state.
@@ -990,10 +1258,10 @@ static void qfq_activate_class(struct qfq_sched *q, struct qfq_class *cl,
* was in ER make sure to adjust V.
*/
if (grp->full_slots) {
- if (!qfq_gt(grp->S, cl->S))
+ if (!qfq_gt(grp->S, agg->S))
goto skip_update;

- /* create a slot for this cl->S */
+ /* create a slot for this agg->S */
qfq_slot_rotate(grp, roundedS);
/* group was surely ineligible, remove */
__clear_bit(grp->index, &q->bitmaps[IR]);
@@ -1008,46 +1276,61 @@ static void qfq_activate_class(struct qfq_sched *q, struct qfq_class *cl,

pr_debug("qfq enqueue: new state %d %#lx S %lld F %lld V %lld\n",
s, q->bitmaps[s],
- (unsigned long long) cl->S,
- (unsigned long long) cl->F,
+ (unsigned long long) agg->S,
+ (unsigned long long) agg->F,
(unsigned long long) q->V);

skip_update:
- qfq_slot_insert(grp, cl, roundedS);
+ qfq_slot_insert(grp, agg, roundedS);
}


+/* Update agg ts and schedule agg for service */
+static void qfq_activate_agg(struct qfq_sched *q, struct qfq_aggregate *agg,
+ enum update_reason reason)
+{
+ qfq_update_agg_ts(q, agg, reason);
+ qfq_schedule_agg(q, agg);
+}
+
static void qfq_slot_remove(struct qfq_sched *q, struct qfq_group *grp,
- struct qfq_class *cl)
+ struct qfq_aggregate *agg)
{
unsigned int i, offset;
u64 roundedS;

- roundedS = qfq_round_down(cl->S, grp->slot_shift);
+ roundedS = qfq_round_down(agg->S, grp->slot_shift);
offset = (roundedS - grp->S) >> grp->slot_shift;
+
i = (grp->front + offset) % QFQ_MAX_SLOTS;

- hlist_del(&cl->next);
+ hlist_del(&agg->next);
if (hlist_empty(&grp->slots[i]))
__clear_bit(offset, &grp->full_slots);
}

/*
- * called to forcibly destroy a queue.
- * If the queue is not in the front bucket, or if it has
- * other queues in the front bucket, we can simply remove
- * the queue with no other side effects.
+ * Called to forcibly deschedule an aggregate. If the aggregate is
+ * not in the front bucket, or if the latter has other aggregates in
+ * the front bucket, we can simply remove the aggregate with no other
+ * side effects.
* Otherwise we must propagate the event up.
*/
-static void qfq_deactivate_class(struct qfq_sched *q, struct qfq_class *cl)
+static void qfq_deactivate_agg(struct qfq_sched *q, struct qfq_aggregate *agg)
{
- struct qfq_group *grp = cl->grp;
+ struct qfq_group *grp = agg->grp;
unsigned long mask;
u64 roundedS;
int s;

- cl->F = cl->S;
- qfq_slot_remove(q, grp, cl);
+ if (agg == q->in_serv_agg) {
+ charge_actual_service(agg);
+ q->in_serv_agg = qfq_choose_next_agg(q);
+ return;
+ }
+
+ agg->F = agg->S;
+ qfq_slot_remove(q, grp, agg);

if (!grp->full_slots) {
__clear_bit(grp->index, &q->bitmaps[IR]);
@@ -1066,8 +1349,8 @@ static void qfq_deactivate_class(struct qfq_sched *q, struct qfq_class *cl)
}
__clear_bit(grp->index, &q->bitmaps[ER]);
} else if (hlist_empty(&grp->slots[grp->front])) {
- cl = qfq_slot_scan(grp);
- roundedS = qfq_round_down(cl->S, grp->slot_shift);
+ agg = qfq_slot_scan(grp);
+ roundedS = qfq_round_down(agg->S, grp->slot_shift);
if (grp->S != roundedS) {
__clear_bit(grp->index, &q->bitmaps[ER]);
__clear_bit(grp->index, &q->bitmaps[IR]);
@@ -1080,7 +1363,7 @@ static void qfq_deactivate_class(struct qfq_sched *q, struct qfq_class *cl)
}
}

- qfq_update_eligible(q, q->V);
+ qfq_update_eligible(q);
}

static void qfq_qlen_notify(struct Qdisc *sch, unsigned long arg)
@@ -1092,6 +1375,32 @@ static void qfq_qlen_notify(struct Qdisc *sch, unsigned long arg)
qfq_deactivate_class(q, cl);
}

+static unsigned int qfq_drop_from_slot(struct qfq_sched *q,
+ struct hlist_head *slot)
+{
+ struct qfq_aggregate *agg;
+ struct hlist_node *n;
+ struct qfq_class *cl;
+ unsigned int len;
+
+ hlist_for_each_entry(agg, n, slot, next) {
+ list_for_each_entry(cl, &agg->active, alist) {
+
+ if (!cl->qdisc->ops->drop)
+ continue;
+
+ len = cl->qdisc->ops->drop(cl->qdisc);
+ if (len > 0) {
+ if (cl->qdisc->q.qlen == 0)
+ qfq_deactivate_class(q, cl);
+
+ return len;
+ }
+ }
+ }
+ return 0;
+}
+
static unsigned int qfq_drop(struct Qdisc *sch)
{
struct qfq_sched *q = qdisc_priv(sch);
@@ -1101,24 +1410,13 @@ static unsigned int qfq_drop(struct Qdisc *sch)
for (i = 0; i <= QFQ_MAX_INDEX; i++) {
grp = &q->groups[i];
for (j = 0; j < QFQ_MAX_SLOTS; j++) {
- struct qfq_class *cl;
- struct hlist_node *n;
-
- hlist_for_each_entry(cl, n, &grp->slots[j], next) {
-
- if (!cl->qdisc->ops->drop)
- continue;
-
- len = cl->qdisc->ops->drop(cl->qdisc);
- if (len > 0) {
- sch->q.qlen--;
- if (!cl->qdisc->q.qlen)
- qfq_deactivate_class(q, cl);
-
- return len;
- }
+ len = qfq_drop_from_slot(q, &grp->slots[j]);
+ if (len > 0) {
+ sch->q.qlen--;
+ return len;
}
}
+
}

return 0;
@@ -1129,44 +1427,51 @@ static int qfq_init_qdisc(struct Qdisc *sch, struct nlattr *opt)
struct qfq_sched *q = qdisc_priv(sch);
struct qfq_group *grp;
int i, j, err;
+ u32 max_cl_shift, maxbudg_shift, max_classes;

err = qdisc_class_hash_init(&q->clhash);
if (err < 0)
return err;

+ if (qdisc_dev(sch)->tx_queue_len + 1 > QFQ_MAX_AGG_CLASSES)
+ max_classes = QFQ_MAX_AGG_CLASSES;
+ else
+ max_classes = qdisc_dev(sch)->tx_queue_len + 1;
+ /* max_cl_shift = floor(log_2(max_classes)) */
+ max_cl_shift = __fls(max_classes);
+ q->max_agg_classes = 1<<max_cl_shift;
+
+ /* maxbudg_shift = log2(max_len * max_classes_per_agg) */
+ maxbudg_shift = QFQ_MTU_SHIFT + max_cl_shift;
+ q->min_slot_shift = FRAC_BITS + maxbudg_shift - QFQ_MAX_INDEX;
+
for (i = 0; i <= QFQ_MAX_INDEX; i++) {
grp = &q->groups[i];
grp->index = i;
- grp->slot_shift = QFQ_MTU_SHIFT + FRAC_BITS
- - (QFQ_MAX_INDEX - i);
+ grp->slot_shift = q->min_slot_shift + i;
for (j = 0; j < QFQ_MAX_SLOTS; j++)
INIT_HLIST_HEAD(&grp->slots[j]);
}

+ INIT_HLIST_HEAD(&q->nonfull_aggs);
+
return 0;
}

static void qfq_reset_qdisc(struct Qdisc *sch)
{
struct qfq_sched *q = qdisc_priv(sch);
- struct qfq_group *grp;
struct qfq_class *cl;
- struct hlist_node *n, *tmp;
- unsigned int i, j;
+ struct hlist_node *n;
+ unsigned int i;

- for (i = 0; i <= QFQ_MAX_INDEX; i++) {
- grp = &q->groups[i];
- for (j = 0; j < QFQ_MAX_SLOTS; j++) {
- hlist_for_each_entry_safe(cl, n, tmp,
- &grp->slots[j], next) {
+ for (i = 0; i < q->clhash.hashsize; i++) {
+ hlist_for_each_entry(cl, n, &q->clhash.hash[i], common.hnode) {
+ if (cl->qdisc->q.qlen > 0)
qfq_deactivate_class(q, cl);
- }
- }
- }

- for (i = 0; i < q->clhash.hashsize; i++) {
- hlist_for_each_entry(cl, n, &q->clhash.hash[i], common.hnode)
qdisc_reset(cl->qdisc);
+ }
}
sch->q.qlen = 0;
}
--
1.7.9.5

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