diff options
Diffstat (limited to 'net/sched/sch_qfq.c')
| -rw-r--r-- | net/sched/sch_qfq.c | 109 |
1 files changed, 79 insertions, 30 deletions
diff --git a/net/sched/sch_qfq.c b/net/sched/sch_qfq.c index f0dd83cff90..9687fa1c227 100644 --- a/net/sched/sch_qfq.c +++ b/net/sched/sch_qfq.c @@ -84,18 +84,19 @@ * 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_INDEX 24 +#define QFQ_MAX_WSHIFT 12 #define QFQ_MAX_WEIGHT (1<<QFQ_MAX_WSHIFT) -#define QFQ_MAX_WSUM (2*QFQ_MAX_WEIGHT) +#define QFQ_MAX_WSUM (16*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_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 */ /* * Possible group states. These values are used as indexes for the bitmaps @@ -231,6 +232,32 @@ static void qfq_update_class_params(struct qfq_sched *q, struct qfq_class *cl, q->wsum += delta_w; } +static void qfq_update_reactivate_class(struct qfq_sched *q, + struct qfq_class *cl, + u32 inv_w, u32 lmax, int delta_w) +{ + bool need_reactivation = false; + int i = qfq_calc_index(inv_w, lmax); + + 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; + } + + qfq_update_class_params(q, cl, lmax, inv_w, delta_w); + + if (need_reactivation) /* activate in new group */ + qfq_activate_class(q, cl, qdisc_peek_len(cl->qdisc)); +} + + static int qfq_change_class(struct Qdisc *sch, u32 classid, u32 parentid, struct nlattr **tca, unsigned long *arg) { @@ -238,7 +265,7 @@ static int qfq_change_class(struct Qdisc *sch, u32 classid, u32 parentid, struct qfq_class *cl = (struct qfq_class *)*arg; struct nlattr *tb[TCA_QFQ_MAX + 1]; u32 weight, lmax, inv_w; - int i, err; + int err; int delta_w; if (tca[TCA_OPTIONS] == NULL) { @@ -270,16 +297,14 @@ static int qfq_change_class(struct Qdisc *sch, u32 classid, u32 parentid, if (tb[TCA_QFQ_LMAX]) { lmax = nla_get_u32(tb[TCA_QFQ_LMAX]); - if (!lmax || lmax > (1UL << QFQ_MTU_SHIFT)) { + if (lmax < QFQ_MIN_LMAX || lmax > (1UL << QFQ_MTU_SHIFT)) { pr_notice("qfq: invalid max length %u\n", lmax); return -EINVAL; } } else - lmax = 1UL << QFQ_MTU_SHIFT; + lmax = psched_mtu(qdisc_dev(sch)); if (cl != NULL) { - bool need_reactivation = false; - if (tca[TCA_RATE]) { err = gen_replace_estimator(&cl->bstats, &cl->rate_est, qdisc_root_sleeping_lock(sch), @@ -291,24 +316,8 @@ static int qfq_change_class(struct Qdisc *sch, u32 classid, u32 parentid, if (lmax == cl->lmax && inv_w == cl->inv_w) return 0; /* nothing to update */ - i = qfq_calc_index(inv_w, lmax); sch_tree_lock(sch); - 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; - } - - qfq_update_class_params(q, cl, lmax, inv_w, delta_w); - - if (need_reactivation) /* activate in new group */ - qfq_activate_class(q, cl, qdisc_peek_len(cl->qdisc)); + qfq_update_reactivate_class(q, cl, inv_w, lmax, delta_w); sch_tree_unlock(sch); return 0; @@ -663,15 +672,48 @@ static void qfq_make_eligible(struct qfq_sched *q, u64 old_V) /* - * 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. + * 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). + * + * With the current values of the above constants, the index is + * then guaranteed to never be higher than 2 + 256 * (1 / 16) = 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. + * + * 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. */ 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; + unsigned int i; /* slot index in the bucket list */ + + 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; + slot = QFQ_MAX_SLOTS - 2; + } + + i = (grp->front + slot) % QFQ_MAX_SLOTS; hlist_add_head(&cl->next, &grp->slots[i]); __set_bit(slot, &grp->full_slots); @@ -892,6 +934,13 @@ 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))) { + 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); + } + err = qdisc_enqueue(skb, cl->qdisc); if (unlikely(err != NET_XMIT_SUCCESS)) { pr_debug("qfq_enqueue: enqueue failed %d\n", err); |