diff options
Diffstat (limited to 'net/sched/sch_qfq.c')
| -rw-r--r-- | net/sched/sch_qfq.c | 1137 |
1 files changed, 1137 insertions, 0 deletions
diff --git a/net/sched/sch_qfq.c b/net/sched/sch_qfq.c new file mode 100644 index 00000000000..10334340859 --- /dev/null +++ b/net/sched/sch_qfq.c @@ -0,0 +1,1137 @@ +/* + * net/sched/sch_qfq.c Quick Fair Queueing Scheduler. + * + * Copyright (c) 2009 Fabio Checconi, Luigi Rizzo, and Paolo Valente. + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public License + * version 2 as published by the Free Software Foundation. + */ + +#include <linux/module.h> +#include <linux/init.h> +#include <linux/bitops.h> +#include <linux/errno.h> +#include <linux/netdevice.h> +#include <linux/pkt_sched.h> +#include <net/sch_generic.h> +#include <net/pkt_sched.h> +#include <net/pkt_cls.h> + + +/* Quick Fair Queueing + =================== + + Sources: + + Fabio Checconi, Luigi Rizzo, and Paolo Valente: "QFQ: Efficient + Packet Scheduling with Tight Bandwidth Distribution Guarantees." + + See also: + http://retis.sssup.it/~fabio/linux/qfq/ + */ + +/* + + Virtual time computations. + + S, F and V are all computed in fixed point arithmetic with + FRAC_BITS decimal bits. + + QFQ_MAX_INDEX is the maximum index allowed for a group. We need + one bit per index. + QFQ_MAX_WSHIFT is the maximum power of two supported as a weight. + + The layout of the bits is as below: + + [ MTU_SHIFT ][ FRAC_BITS ] + [ MAX_INDEX ][ MIN_SLOT_SHIFT ] + ^.__grp->index = 0 + *.__grp->slot_shift + + where MIN_SLOT_SHIFT is derived by difference from the others. + + The max group index corresponds to Lmax/w_min, where + Lmax=1<<MTU_SHIFT, w_min = 1 . + From this, and knowing how many groups (MAX_INDEX) we want, + we can derive the shift corresponding to each group. + + Because we often need to compute + F = S + len/w_i and V = V + len/wsum + instead of storing w_i store the value + inv_w = (1<<FRAC_BITS)/w_i + so we can do F = S + len * inv_w * wsum. + We use W_TOT in the formulas so we can easily move between + static and adaptive weight sum. + + The per-scheduler-instance data contain all the data structures + for the scheduler: bitmaps and bucket lists. + + */ + +/* + * Maximum number of consecutive slots occupied by backlogged classes + * inside a group. + */ +#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 + * group with the smallest index that can support the L_i / r_i configured + * for the class. + * + * 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 19 +#define QFQ_MAX_WSHIFT 16 + +#define QFQ_MAX_WEIGHT (1<<QFQ_MAX_WSHIFT) +#define QFQ_MAX_WSUM (2*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 11 +#define QFQ_MIN_SLOT_SHIFT (FRAC_BITS + QFQ_MTU_SHIFT - QFQ_MAX_INDEX) + +/* + * Possible group states. These values are used as indexes for the bitmaps + * array of struct qfq_queue. + */ +enum qfq_state { ER, IR, EB, IB, QFQ_MAX_STATE }; + +struct qfq_group; + +struct qfq_class { + struct Qdisc_class_common common; + + unsigned int refcnt; + unsigned int filter_cnt; + + struct gnet_stats_basic_packed bstats; + struct gnet_stats_queue qstats; + struct gnet_stats_rate_est rate_est; + struct Qdisc *qdisc; + + struct hlist_node next; /* Link for the slot list. */ + u64 S, F; /* flow timestamps (exact) */ + + /* group we belong to. In principle we would need the index, + * which is log_2(lmax/weight), but we never reference it + * directly, only the group. + */ + struct qfq_group *grp; + + /* these are copied from the flowset. */ + u32 inv_w; /* ONE_FP/weight */ + u32 lmax; /* Max packet size for this flow. */ +}; + +struct qfq_group { + u64 S, F; /* group timestamps (approx). */ + unsigned int slot_shift; /* Slot shift. */ + unsigned int index; /* Group index. */ + unsigned int front; /* Index of the front slot. */ + unsigned long full_slots; /* non-empty slots */ + + /* Array of RR lists of active classes. */ + struct hlist_head slots[QFQ_MAX_SLOTS]; +}; + +struct qfq_sched { + struct tcf_proto *filter_list; + struct Qdisc_class_hash clhash; + + u64 V; /* Precise virtual time. */ + u32 wsum; /* weight sum */ + + unsigned long bitmaps[QFQ_MAX_STATE]; /* Group bitmaps. */ + struct qfq_group groups[QFQ_MAX_INDEX + 1]; /* The groups. */ +}; + +static struct qfq_class *qfq_find_class(struct Qdisc *sch, u32 classid) +{ + struct qfq_sched *q = qdisc_priv(sch); + struct Qdisc_class_common *clc; + + clc = qdisc_class_find(&q->clhash, classid); + if (clc == NULL) + return NULL; + return container_of(clc, struct qfq_class, common); +} + +static void qfq_purge_queue(struct qfq_class *cl) +{ + unsigned int len = cl->qdisc->q.qlen; + + qdisc_reset(cl->qdisc); + qdisc_tree_decrease_qlen(cl->qdisc, len); +} + +static const struct nla_policy qfq_policy[TCA_QFQ_MAX + 1] = { + [TCA_QFQ_WEIGHT] = { .type = NLA_U32 }, + [TCA_QFQ_LMAX] = { .type = NLA_U32 }, +}; + +/* + * Calculate a flow index, given its weight and maximum packet length. + * 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) +{ + u64 slot_size = (u64)maxlen * inv_w; + unsigned long size_map; + int index = 0; + + size_map = slot_size >> QFQ_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))); + + if (index < 0) + index = 0; +out: + pr_debug("qfq calc_index: W = %lu, L = %u, I = %d\n", + (unsigned long) ONE_FP/inv_w, maxlen, index); + + return index; +} + +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; + struct nlattr *tb[TCA_QFQ_MAX + 1]; + u32 weight, lmax, inv_w; + int i, err; + + if (tca[TCA_OPTIONS] == NULL) { + pr_notice("qfq: no options\n"); + return -EINVAL; + } + + err = nla_parse_nested(tb, TCA_QFQ_MAX, tca[TCA_OPTIONS], qfq_policy); + if (err < 0) + return err; + + if (tb[TCA_QFQ_WEIGHT]) { + weight = nla_get_u32(tb[TCA_QFQ_WEIGHT]); + if (!weight || weight > (1UL << QFQ_MAX_WSHIFT)) { + pr_notice("qfq: invalid weight %u\n", weight); + return -EINVAL; + } + } else + weight = 1; + + inv_w = ONE_FP / weight; + weight = ONE_FP / inv_w; + if (q->wsum + weight > QFQ_MAX_WSUM) { + pr_notice("qfq: total weight out of range (%u + %u)\n", + weight, q->wsum); + return -EINVAL; + } + + if (tb[TCA_QFQ_LMAX]) { + lmax = nla_get_u32(tb[TCA_QFQ_LMAX]); + if (!lmax || lmax > (1UL << QFQ_MTU_SHIFT)) { + pr_notice("qfq: invalid max length %u\n", lmax); + return -EINVAL; + } + } else + lmax = 1UL << QFQ_MTU_SHIFT; + + if (cl != NULL) { + if (tca[TCA_RATE]) { + err = gen_replace_estimator(&cl->bstats, &cl->rate_est, + qdisc_root_sleeping_lock(sch), + tca[TCA_RATE]); + if (err) + return err; + } + + sch_tree_lock(sch); + if (tb[TCA_QFQ_WEIGHT]) { + q->wsum = weight - ONE_FP / cl->inv_w; + cl->inv_w = inv_w; + } + sch_tree_unlock(sch); + + return 0; + } + + cl = kzalloc(sizeof(struct qfq_class), GFP_KERNEL); + if (cl == NULL) + return -ENOBUFS; + + cl->refcnt = 1; + cl->common.classid = classid; + cl->lmax = lmax; + cl->inv_w = inv_w; + i = qfq_calc_index(cl->inv_w, cl->lmax); + + cl->grp = &q->groups[i]; + q->wsum += weight; + + cl->qdisc = qdisc_create_dflt(sch->dev_queue, + &pfifo_qdisc_ops, classid); + if (cl->qdisc == NULL) + cl->qdisc = &noop_qdisc; + + if (tca[TCA_RATE]) { + 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; + } + } + + sch_tree_lock(sch); + qdisc_class_hash_insert(&q->clhash, &cl->common); + sch_tree_unlock(sch); + + qdisc_class_hash_grow(sch, &q->clhash); + + *arg = (unsigned long)cl; + return 0; +} + +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; + } + + gen_kill_estimator(&cl->bstats, &cl->rate_est); + qdisc_destroy(cl->qdisc); + kfree(cl); +} + +static int qfq_delete_class(struct Qdisc *sch, unsigned long arg) +{ + struct qfq_sched *q = qdisc_priv(sch); + struct qfq_class *cl = (struct qfq_class *)arg; + + if (cl->filter_cnt > 0) + return -EBUSY; + + sch_tree_lock(sch); + + qfq_purge_queue(cl); + qdisc_class_hash_remove(&q->clhash, &cl->common); + + BUG_ON(--cl->refcnt == 0); + /* + * This shouldn't happen: we "hold" one cops->get() when called + * from tc_ctl_tclass; the destroy method is done from cops->put(). + */ + + sch_tree_unlock(sch); + return 0; +} + +static unsigned long qfq_get_class(struct Qdisc *sch, u32 classid) +{ + struct qfq_class *cl = qfq_find_class(sch, classid); + + if (cl != NULL) + cl->refcnt++; + + return (unsigned long)cl; +} + +static void qfq_put_class(struct Qdisc *sch, unsigned long arg) +{ + struct qfq_class *cl = (struct qfq_class *)arg; + + if (--cl->refcnt == 0) + qfq_destroy_class(sch, cl); +} + +static struct tcf_proto **qfq_tcf_chain(struct Qdisc *sch, unsigned long cl) +{ + struct qfq_sched *q = qdisc_priv(sch); + + if (cl) + return NULL; + + return &q->filter_list; +} + +static unsigned long qfq_bind_tcf(struct Qdisc *sch, unsigned long parent, + u32 classid) +{ + struct qfq_class *cl = qfq_find_class(sch, classid); + + if (cl != NULL) + cl->filter_cnt++; + + return (unsigned long)cl; +} + +static void qfq_unbind_tcf(struct Qdisc *sch, unsigned long arg) +{ + struct qfq_class *cl = (struct qfq_class *)arg; + + cl->filter_cnt--; +} + +static int qfq_graft_class(struct Qdisc *sch, unsigned long arg, + struct Qdisc *new, struct Qdisc **old) +{ + struct qfq_class *cl = (struct qfq_class *)arg; + + if (new == NULL) { + new = qdisc_create_dflt(sch->dev_queue, + &pfifo_qdisc_ops, cl->common.classid); + if (new == NULL) + new = &noop_qdisc; + } + + sch_tree_lock(sch); + qfq_purge_queue(cl); + *old = cl->qdisc; + cl->qdisc = new; + sch_tree_unlock(sch); + return 0; +} + +static struct Qdisc *qfq_class_leaf(struct Qdisc *sch, unsigned long arg) +{ + struct qfq_class *cl = (struct qfq_class *)arg; + + return cl->qdisc; +} + +static int qfq_dump_class(struct Qdisc *sch, unsigned long arg, + struct sk_buff *skb, struct tcmsg *tcm) +{ + struct qfq_class *cl = (struct qfq_class *)arg; + struct nlattr *nest; + + tcm->tcm_parent = TC_H_ROOT; + tcm->tcm_handle = cl->common.classid; + tcm->tcm_info = cl->qdisc->handle; + + nest = nla_nest_start(skb, TCA_OPTIONS); + if (nest == NULL) + goto nla_put_failure; + NLA_PUT_U32(skb, TCA_QFQ_WEIGHT, ONE_FP/cl->inv_w); + NLA_PUT_U32(skb, TCA_QFQ_LMAX, cl->lmax); + return nla_nest_end(skb, nest); + +nla_put_failure: + nla_nest_cancel(skb, nest); + return -EMSGSIZE; +} + +static int qfq_dump_class_stats(struct Qdisc *sch, unsigned long arg, + struct gnet_dump *d) +{ + struct qfq_class *cl = (struct qfq_class *)arg; + struct tc_qfq_stats xstats; + + memset(&xstats, 0, sizeof(xstats)); + cl->qdisc->qstats.qlen = cl->qdisc->q.qlen; + + xstats.weight = ONE_FP/cl->inv_w; + xstats.lmax = cl->lmax; + + if (gnet_stats_copy_basic(d, &cl->bstats) < 0 || + gnet_stats_copy_rate_est(d, &cl->bstats, &cl->rate_est) < 0 || + gnet_stats_copy_queue(d, &cl->qdisc->qstats) < 0) + return -1; + + return gnet_stats_copy_app(d, &xstats, sizeof(xstats)); +} + +static void qfq_walk(struct Qdisc *sch, struct qdisc_walker *arg) +{ + struct qfq_sched *q = qdisc_priv(sch); + struct qfq_class *cl; + struct hlist_node *n; + unsigned int i; + + if (arg->stop) + return; + + for (i = 0; i < q->clhash.hashsize; i++) { + hlist_for_each_entry(cl, n, &q->clhash.hash[i], common.hnode) { + if (arg->count < arg->skip) { + arg->count++; + continue; + } + if (arg->fn(sch, (unsigned long)cl, arg) < 0) { + arg->stop = 1; + return; + } + arg->count++; + } + } +} + +static struct qfq_class *qfq_classify(struct sk_buff *skb, struct Qdisc *sch, + int *qerr) +{ + struct qfq_sched *q = qdisc_priv(sch); + struct qfq_class *cl; + struct tcf_result res; + int result; + + if (TC_H_MAJ(skb->priority ^ sch->handle) == 0) { + pr_debug("qfq_classify: found %d\n", skb->priority); + cl = qfq_find_class(sch, skb->priority); + if (cl != NULL) + return cl; + } + + *qerr = NET_XMIT_SUCCESS | __NET_XMIT_BYPASS; + result = tc_classify(skb, q->filter_list, &res); + if (result >= 0) { +#ifdef CONFIG_NET_CLS_ACT + switch (result) { + case TC_ACT_QUEUED: + case TC_ACT_STOLEN: + *qerr = NET_XMIT_SUCCESS | __NET_XMIT_STOLEN; + case TC_ACT_SHOT: + return NULL; + } +#endif + cl = (struct qfq_class *)res.class; + if (cl == NULL) + cl = qfq_find_class(sch, res.classid); + return cl; + } + + return NULL; +} + +/* Generic comparison function, handling wraparound. */ +static inline int qfq_gt(u64 a, u64 b) +{ + return (s64)(a - b) > 0; +} + +/* Round a precise timestamp to its slotted value. */ +static inline u64 qfq_round_down(u64 ts, unsigned int shift) +{ + return ts & ~((1ULL << shift) - 1); +} + +/* return the pointer to the group with lowest index in the bitmap */ +static inline struct qfq_group *qfq_ffs(struct qfq_sched *q, + unsigned long bitmap) +{ + int index = __ffs(bitmap); + return &q->groups[index]; +} +/* Calculate a mask to mimic what would be ffs_from(). */ +static inline unsigned long mask_from(unsigned long bitmap, int from) +{ + return bitmap & ~((1UL << from) - 1); +} + +/* + * The state computation relies on ER=0, IR=1, EB=2, IB=3 + * First compute eligibility comparing grp->S, q->V, + * then check if someone is blocking us and possibly add EB + */ +static int qfq_calc_state(struct qfq_sched *q, const struct qfq_group *grp) +{ + /* if S > V we are not eligible */ + unsigned int state = qfq_gt(grp->S, q->V); + unsigned long mask = mask_from(q->bitmaps[ER], grp->index); + struct qfq_group *next; + + if (mask) { + next = qfq_ffs(q, mask); + if (qfq_gt(grp->F, next->F)) + state |= EB; + } + + return state; +} + + +/* + * In principle + * q->bitmaps[dst] |= q->bitmaps[src] & mask; + * q->bitmaps[src] &= ~mask; + * but we should make sure that src != dst + */ +static inline void qfq_move_groups(struct qfq_sched *q, unsigned long mask, + int src, int dst) +{ + q->bitmaps[dst] |= q->bitmaps[src] & mask; + q->bitmaps[src] &= ~mask; +} + +static void qfq_unblock_groups(struct qfq_sched *q, int index, u64 old_F) +{ + unsigned long mask = mask_from(q->bitmaps[ER], index + 1); + struct qfq_group *next; + + if (mask) { + next = qfq_ffs(q, mask); + if (!qfq_gt(next->F, old_F)) + return; + } + + mask = (1UL << index) - 1; + qfq_move_groups(q, mask, EB, ER); + qfq_move_groups(q, mask, IB, IR); +} + +/* + * perhaps + * + old_V ^= q->V; + old_V >>= QFQ_MIN_SLOT_SHIFT; + if (old_V) { + ... + } + * + */ +static void qfq_make_eligible(struct qfq_sched *q, u64 old_V) +{ + unsigned long vslot = q->V >> QFQ_MIN_SLOT_SHIFT; + unsigned long old_vslot = old_V >> QFQ_MIN_SLOT_SHIFT; + + if (vslot != old_vslot) { + unsigned long mask = (1UL << fls(vslot ^ old_vslot)) - 1; + qfq_move_groups(q, mask, IR, ER); + qfq_move_groups(q, mask, IB, EB); + } +} + + +/* + * XXX we should make sure that slot becomes less than 32. + * This is guaranteed by the input values. + * roundedS is always cl->S rounded on grp->slot_shift bits. + */ +static void qfq_slot_insert(struct qfq_group *grp, struct qfq_class *cl, + u64 roundedS) +{ + u64 slot = (roundedS - grp->S) >> grp->slot_shift; + unsigned int i = (grp->front + slot) % QFQ_MAX_SLOTS; + + hlist_add_head(&cl->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) +{ + return hlist_entry(grp->slots[grp->front].first, + struct qfq_class, next); +} + +/* + * remove the entry from the slot + */ +static void qfq_front_slot_remove(struct qfq_group *grp) +{ + struct qfq_class *cl = qfq_slot_head(grp); + + BUG_ON(!cl); + hlist_del(&cl->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. + */ +static struct qfq_class *qfq_slot_scan(struct qfq_group *grp) +{ + unsigned int i; + + pr_debug("qfq slot_scan: grp %u full %#lx\n", + grp->index, grp->full_slots); + + if (grp->full_slots == 0) + return NULL; + + i = __ffs(grp->full_slots); /* zero based */ + if (i > 0) { + grp->front = (grp->front + i) % QFQ_MAX_SLOTS; + grp->full_slots >>= i; + } + + return qfq_slot_head(grp); +} + +/* + * adjust the bucket list. When the start time of a group decreases, + * we move the index down (modulo QFQ_MAX_SLOTS) so we don't need to + * move the objects. The mask of occupied slots must be shifted + * because we use ffs() to find the first non-empty slot. + * This covers decreases in the group's start time, but what about + * increases of the start time ? + * Here too we should make sure that i is less than 32 + */ +static void qfq_slot_rotate(struct qfq_group *grp, u64 roundedS) +{ + unsigned int i = (grp->S - roundedS) >> grp->slot_shift; + + grp->full_slots <<= i; + grp->front = (grp->front - i) % QFQ_MAX_SLOTS; +} + +static void qfq_update_eligible(struct qfq_sched *q, u64 old_V) +{ + struct qfq_group *grp; + unsigned long ineligible; + + ineligible = q->bitmaps[IR] | q->bitmaps[IB]; + if (ineligible) { + if (!q->bitmaps[ER]) { + grp = qfq_ffs(q, ineligible); + if (qfq_gt(grp->S, q->V)) + q->V = grp->S; + } + qfq_make_eligible(q, old_V); + } +} + +/* What is length of next packet in queue (0 if queue is empty) */ +static unsigned int qdisc_peek_len(struct Qdisc *sch) +{ + struct sk_buff *skb; + + skb = sch->ops->peek(sch); + return skb ? qdisc_pkt_len(skb) : 0; +} + +/* + * 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) +{ + 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; + + cl->F = cl->S + (u64)len * cl->inv_w; + roundedS = qfq_round_down(cl->S, grp->slot_shift); + if (roundedS == grp->S) + return false; + + qfq_front_slot_remove(grp); + qfq_slot_insert(grp, cl, roundedS); + } + + return true; +} + +static struct sk_buff *qfq_dequeue(struct Qdisc *sch) +{ + struct qfq_sched *q = qdisc_priv(sch); + struct qfq_group *grp; + struct qfq_class *cl; + struct sk_buff *skb; + unsigned int len; + u64 old_V; + + if (!q->bitmaps[ER]) + return NULL; + + grp = qfq_ffs(q, q->bitmaps[ER]); + + cl = qfq_slot_head(grp); + skb = qdisc_dequeue_peeked(cl->qdisc); + if (!skb) { + WARN_ONCE(1, "qfq_dequeue: non-workconserving leaf\n"); + return NULL; + } + + sch->q.qlen--; + qdisc_bstats_update(sch, skb); + + old_V = q->V; + len = qdisc_pkt_len(skb); + 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); + + if (qfq_update_class(grp, cl)) { + u64 old_F = grp->F; + + 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; + + 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_unblock_groups(q, grp->index, old_F); + } + +skip_unblock: + qfq_update_eligible(q, old_V); + + return skb; +} + +/* + * Assign a reasonable start time for a new flow k 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. + * 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) +{ + unsigned long mask; + uint32_t limit, roundedF; + int slot_shift = cl->grp->slot_shift; + + roundedF = qfq_round_down(cl->F, slot_shift); + limit = qfq_round_down(q->V, slot_shift) + (1UL << slot_shift); + + if (!qfq_gt(cl->F, q->V) || qfq_gt(roundedF, limit)) { + /* timestamp was stale */ + mask = mask_from(q->bitmaps[ER], cl->grp->index); + if (mask) { + struct qfq_group *next = qfq_ffs(q, mask); + if (qfq_gt(roundedF, next->F)) { + cl->S = next->F; + return; + } + } + cl->S = q->V; + } else /* timestamp is not stale */ + cl->S = cl->F; +} + +static int qfq_enqueue(struct sk_buff *skb, struct Qdisc *sch) +{ + struct qfq_sched *q = qdisc_priv(sch); + struct qfq_group *grp; + struct qfq_class *cl; + int err; + u64 roundedS; + int s; + + cl = qfq_classify(skb, sch, &err); + if (cl == NULL) { + if (err & __NET_XMIT_BYPASS) + sch->qstats.drops++; + kfree_skb(skb); + return err; + } + pr_debug("qfq_enqueue: cl = %x\n", cl->common.classid); + + err = qdisc_enqueue(skb, cl->qdisc); + if (unlikely(err != NET_XMIT_SUCCESS)) { + pr_debug("qfq_enqueue: enqueue failed %d\n", err); + if (net_xmit_drop_count(err)) { + cl->qstats.drops++; + sch->qstats.drops++; + } + return err; + } + + 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) + return err; + + /* If reach this point, queue q was idle */ + grp = cl->grp; + qfq_update_start(q, cl); + + /* compute new finish time and rounded start. */ + cl->F = cl->S + (u64)qdisc_pkt_len(skb) * cl->inv_w; + roundedS = qfq_round_down(cl->S, grp->slot_shift); + + /* + * insert cl in the correct bucket. + * If cl->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. + * Finally, if there were no flows in this group and nobody + * was in ER make sure to adjust V. + */ + if (grp->full_slots) { + if (!qfq_gt(grp->S, cl->S)) + goto skip_update; + + /* create a slot for this cl->S */ + qfq_slot_rotate(grp, roundedS); + /* group was surely ineligible, remove */ + __clear_bit(grp->index, &q->bitmaps[IR]); + __clear_bit(grp->index, &q->bitmaps[IB]); + } else if (!q->bitmaps[ER] && qfq_gt(roundedS, q->V)) + q->V = roundedS; + + grp->S = roundedS; + grp->F = roundedS + (2ULL << grp->slot_shift); + s = qfq_calc_state(q, grp); + __set_bit(grp->index, &q->bitmaps[s]); + + 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) q->V); + +skip_update: + qfq_slot_insert(grp, cl, roundedS); + + return err; +} + + +static void qfq_slot_remove(struct qfq_sched *q, struct qfq_group *grp, + struct qfq_class *cl) +{ + unsigned int i, offset; + u64 roundedS; + + roundedS = qfq_round_down(cl->S, grp->slot_shift); + offset = (roundedS - grp->S) >> grp->slot_shift; + i = (grp->front + offset) % QFQ_MAX_SLOTS; + + hlist_del(&cl->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. + * Otherwise we must propagate the event up. + */ +static void qfq_deactivate_class(struct qfq_sched *q, struct qfq_class *cl) +{ + struct qfq_group *grp = cl->grp; + unsigned long mask; + u64 roundedS; + int s; + + cl->F = cl->S; + qfq_slot_remove(q, grp, cl); + + if (!grp->full_slots) { + __clear_bit(grp->index, &q->bitmaps[IR]); + __clear_bit(grp->index, &q->bitmaps[EB]); + __clear_bit(grp->index, &q->bitmaps[IB]); + + if (test_bit(grp->index, &q->bitmaps[ER]) && + !(q->bitmaps[ER] & ~((1UL << grp->index) - 1))) { + mask = q->bitmaps[ER] & ((1UL << grp->index) - 1); + if (mask) + mask = ~((1UL << __fls(mask)) - 1); + else + mask = ~0UL; + qfq_move_groups(q, mask, EB, ER); + qfq_move_groups(q, mask, IB, IR); + } + __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); + if (grp->S != roundedS) { + __clear_bit(grp->index, &q->bitmaps[ER]); + __clear_bit(grp->index, &q->bitmaps[IR]); + __clear_bit(grp->index, &q->bitmaps[EB]); + __clear_bit(grp->index, &q->bitmaps[IB]); + grp->S = roundedS; + grp->F = roundedS + (2ULL << grp->slot_shift); + s = qfq_calc_state(q, grp); + __set_bit(grp->index, &q->bitmaps[s]); + } + } + + qfq_update_eligible(q, q->V); +} + +static void qfq_qlen_notify(struct Qdisc *sch, unsigned long arg) +{ + struct qfq_sched *q = qdisc_priv(sch); + struct qfq_class *cl = (struct qfq_class *)arg; + + if (cl->qdisc->q.qlen == 0) + qfq_deactivate_class(q, cl); +} + +static unsigned int qfq_drop(struct Qdisc *sch) +{ + struct qfq_sched *q = qdisc_priv(sch); + struct qfq_group *grp; + unsigned int i, j, len; + + 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; + } + } + } + } + + return 0; +} + +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; + + err = qdisc_class_hash_init(&q->clhash); + if (err < 0) + return err; + + 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); + for (j = 0; j < QFQ_MAX_SLOTS; j++) + INIT_HLIST_HEAD(&grp->slots[j]); + } + + 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; + + 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) { + 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; +} + +static void qfq_destroy_qdisc(struct Qdisc *sch) +{ + struct qfq_sched *q = qdisc_priv(sch); + struct qfq_class *cl; + struct hlist_node *n, *next; + unsigned int i; + + tcf_destroy_chain(&q->filter_list); + + for (i = 0; i < q->clhash.hashsize; i++) { + hlist_for_each_entry_safe(cl, n, next, &q->clhash.hash[i], + common.hnode) { + qfq_destroy_class(sch, cl); + } + } + qdisc_class_hash_destroy(&q->clhash); +} + +static const struct Qdisc_class_ops qfq_class_ops = { + .change = qfq_change_class, + .delete = qfq_delete_class, + .get = qfq_get_class, + .put = qfq_put_class, + .tcf_chain = qfq_tcf_chain, + .bind_tcf = qfq_bind_tcf, + .unbind_tcf = qfq_unbind_tcf, + .graft = qfq_graft_class, + .leaf = qfq_class_leaf, + .qlen_notify = qfq_qlen_notify, + .dump = qfq_dump_class, + .dump_stats = qfq_dump_class_stats, + .walk = qfq_walk, +}; + +static struct Qdisc_ops qfq_qdisc_ops __read_mostly = { + .cl_ops = &qfq_class_ops, + .id = "qfq", + .priv_size = sizeof(struct qfq_sched), + .enqueue = qfq_enqueue, + .dequeue = qfq_dequeue, + .peek = qdisc_peek_dequeued, + .drop = qfq_drop, + .init = qfq_init_qdisc, + .reset = qfq_reset_qdisc, + .destroy = qfq_destroy_qdisc, + .owner = THIS_MODULE, +}; + +static int __init qfq_init(void) +{ + return register_qdisc(&qfq_qdisc_ops); +} + +static void __exit qfq_exit(void) +{ + unregister_qdisc(&qfq_qdisc_ops); +} + +module_init(qfq_init); +module_exit(qfq_exit); +MODULE_LICENSE("GPL"); |