X-Git-Url: http://git.onelab.eu/?a=blobdiff_plain;f=net%2Fsched%2Fsch_red.c;h=acddad08850fa65d1082e2d5377b8fd9d3956b4b;hb=refs%2Fheads%2Fvserver;hp=e98f79bdb435dee959745b7e714966e0bb7f6956;hpb=c7b5ebbddf7bcd3651947760f423e3783bbe6573;p=linux-2.6.git diff --git a/net/sched/sch_red.c b/net/sched/sch_red.c index e98f79bdb..acddad088 100644 --- a/net/sched/sch_red.c +++ b/net/sched/sch_red.c @@ -9,76 +9,22 @@ * Authors: Alexey Kuznetsov, * * Changes: - * J Hadi Salim 980914: computation fixes + * J Hadi Salim 980914: computation fixes * Alexey Makarenko 990814: qave on idle link was calculated incorrectly. - * J Hadi Salim 980816: ECN support + * J Hadi Salim 980816: ECN support */ -#include #include -#include -#include -#include #include #include -#include -#include -#include -#include -#include -#include -#include -#include -#include -#include #include -#include -#include -#include -#include #include -#include #include #include -#include +#include -/* Random Early Detection (RED) algorithm. - ======================================= - - Source: Sally Floyd and Van Jacobson, "Random Early Detection Gateways - for Congestion Avoidance", 1993, IEEE/ACM Transactions on Networking. - - This file codes a "divisionless" version of RED algorithm - as written down in Fig.17 of the paper. - -Short description. ------------------- - - When a new packet arrives we calculate the average queue length: - - avg = (1-W)*avg + W*current_queue_len, - - W is the filter time constant (chosen as 2^(-Wlog)), it controls - the inertia of the algorithm. To allow larger bursts, W should be - decreased. - - if (avg > th_max) -> packet marked (dropped). - if (avg < th_min) -> packet passes. - if (th_min < avg < th_max) we calculate probability: - - Pb = max_P * (avg - th_min)/(th_max-th_min) - - and mark (drop) packet with this probability. - Pb changes from 0 (at avg==th_min) to max_P (avg==th_max). - max_P should be small (not 1), usually 0.01..0.02 is good value. - - max_P is chosen as a number, so that max_P/(th_max-th_min) - is a negative power of two in order arithmetics to contain - only shifts. - - - Parameters, settable by user: +/* Parameters, settable by user: ----------------------------- limit - bytes (must be > qth_max + burst) @@ -89,259 +35,128 @@ Short description. arbitrarily high (well, less than ram size) Really, this limit will never be reached if RED works correctly. - - qth_min - bytes (should be < qth_max/2) - qth_max - bytes (should be at least 2*qth_min and less limit) - Wlog - bits (<32) log(1/W). - Plog - bits (<32) - - Plog is related to max_P by formula: - - max_P = (qth_max-qth_min)/2^Plog; - - F.e. if qth_max=128K and qth_min=32K, then Plog=22 - corresponds to max_P=0.02 - - Scell_log - Stab - - Lookup table for log((1-W)^(t/t_ave). - - -NOTES: - -Upper bound on W. ------------------ - - If you want to allow bursts of L packets of size S, - you should choose W: - - L + 1 - th_min/S < (1-(1-W)^L)/W - - th_min/S = 32 th_min/S = 4 - - log(W) L - -1 33 - -2 35 - -3 39 - -4 46 - -5 57 - -6 75 - -7 101 - -8 135 - -9 190 - etc. */ struct red_sched_data { -/* Parameters */ - u32 limit; /* HARD maximal queue length */ - u32 qth_min; /* Min average length threshold: A scaled */ - u32 qth_max; /* Max average length threshold: A scaled */ - u32 Rmask; - u32 Scell_max; - unsigned char flags; - char Wlog; /* log(W) */ - char Plog; /* random number bits */ - char Scell_log; - u8 Stab[256]; - -/* Variables */ - unsigned long qave; /* Average queue length: A scaled */ - int qcount; /* Packets since last random number generation */ - u32 qR; /* Cached random number */ - - psched_time_t qidlestart; /* Start of idle period */ - struct tc_red_xstats st; + u32 limit; /* HARD maximal queue length */ + unsigned char flags; + struct red_parms parms; + struct red_stats stats; + struct Qdisc *qdisc; }; -static int red_ecn_mark(struct sk_buff *skb) +static inline int red_use_ecn(struct red_sched_data *q) { - if (skb->nh.raw + 20 > skb->tail) - return 0; - - switch (skb->protocol) { - case __constant_htons(ETH_P_IP): - if (INET_ECN_is_not_ect(skb->nh.iph->tos)) - return 0; - IP_ECN_set_ce(skb->nh.iph); - return 1; - case __constant_htons(ETH_P_IPV6): - if (INET_ECN_is_not_ect(ipv6_get_dsfield(skb->nh.ipv6h))) - return 0; - IP6_ECN_set_ce(skb->nh.ipv6h); - return 1; - default: - return 0; - } + return q->flags & TC_RED_ECN; } -static int -red_enqueue(struct sk_buff *skb, struct Qdisc* sch) +static inline int red_use_harddrop(struct red_sched_data *q) { - struct red_sched_data *q = qdisc_priv(sch); - - psched_time_t now; - - if (!PSCHED_IS_PASTPERFECT(q->qidlestart)) { - long us_idle; - int shift; - - PSCHED_GET_TIME(now); - us_idle = PSCHED_TDIFF_SAFE(now, q->qidlestart, q->Scell_max); - PSCHED_SET_PASTPERFECT(q->qidlestart); - -/* - The problem: ideally, average length queue recalcultion should - be done over constant clock intervals. This is too expensive, so that - the calculation is driven by outgoing packets. - When the queue is idle we have to model this clock by hand. - - SF+VJ proposed to "generate" m = idletime/(average_pkt_size/bandwidth) - dummy packets as a burst after idle time, i.e. - - q->qave *= (1-W)^m - - This is an apparently overcomplicated solution (f.e. we have to precompute - a table to make this calculation in reasonable time) - I believe that a simpler model may be used here, - but it is field for experiments. -*/ - shift = q->Stab[us_idle>>q->Scell_log]; - - if (shift) { - q->qave >>= shift; - } else { - /* Approximate initial part of exponent - with linear function: - (1-W)^m ~= 1-mW + ... - - Seems, it is the best solution to - problem of too coarce exponent tabulation. - */ - - us_idle = (q->qave * us_idle)>>q->Scell_log; - if (us_idle < q->qave/2) - q->qave -= us_idle; - else - q->qave >>= 1; - } - } else { - q->qave += sch->stats.backlog - (q->qave >> q->Wlog); - /* NOTE: - q->qave is fixed point number with point at Wlog. - The formulae above is equvalent to floating point - version: - - qave = qave*(1-W) + sch->stats.backlog*W; - --ANK (980924) - */ - } + return q->flags & TC_RED_HARDDROP; +} - if (q->qave < q->qth_min) { - q->qcount = -1; -enqueue: - if (sch->stats.backlog + skb->len <= q->limit) { - __skb_queue_tail(&sch->q, skb); - sch->stats.backlog += skb->len; - sch->stats.bytes += skb->len; - sch->stats.packets++; - return NET_XMIT_SUCCESS; - } else { - q->st.pdrop++; - } - kfree_skb(skb); - sch->stats.drops++; - return NET_XMIT_DROP; - } - if (q->qave >= q->qth_max) { - q->qcount = -1; - sch->stats.overlimits++; -mark: - if (!(q->flags&TC_RED_ECN) || !red_ecn_mark(skb)) { - q->st.early++; - goto drop; - } - q->st.marked++; - goto enqueue; +static int red_enqueue(struct sk_buff *skb, struct Qdisc* sch) +{ + struct red_sched_data *q = qdisc_priv(sch); + struct Qdisc *child = q->qdisc; + int ret; + + q->parms.qavg = red_calc_qavg(&q->parms, child->qstats.backlog); + + if (red_is_idling(&q->parms)) + red_end_of_idle_period(&q->parms); + + switch (red_action(&q->parms, q->parms.qavg)) { + case RED_DONT_MARK: + break; + + case RED_PROB_MARK: + sch->qstats.overlimits++; + if (!red_use_ecn(q) || !INET_ECN_set_ce(skb)) { + q->stats.prob_drop++; + goto congestion_drop; + } + + q->stats.prob_mark++; + break; + + case RED_HARD_MARK: + sch->qstats.overlimits++; + if (red_use_harddrop(q) || !red_use_ecn(q) || + !INET_ECN_set_ce(skb)) { + q->stats.forced_drop++; + goto congestion_drop; + } + + q->stats.forced_mark++; + break; } - if (++q->qcount) { - /* The formula used below causes questions. - - OK. qR is random number in the interval 0..Rmask - i.e. 0..(2^Plog). If we used floating point - arithmetics, it would be: (2^Plog)*rnd_num, - where rnd_num is less 1. - - Taking into account, that qave have fixed - point at Wlog, and Plog is related to max_P by - max_P = (qth_max-qth_min)/2^Plog; two lines - below have the following floating point equivalent: - - max_P*(qave - qth_min)/(qth_max-qth_min) < rnd/qcount - - Any questions? --ANK (980924) - */ - if (((q->qave - q->qth_min)>>q->Wlog)*q->qcount < q->qR) - goto enqueue; - q->qcount = 0; - q->qR = net_random()&q->Rmask; - sch->stats.overlimits++; - goto mark; + ret = child->enqueue(skb, child); + if (likely(ret == NET_XMIT_SUCCESS)) { + sch->bstats.bytes += skb->len; + sch->bstats.packets++; + sch->q.qlen++; + } else { + q->stats.pdrop++; + sch->qstats.drops++; } - q->qR = net_random()&q->Rmask; - goto enqueue; + return ret; -drop: - kfree_skb(skb); - sch->stats.drops++; +congestion_drop: + qdisc_drop(skb, sch); return NET_XMIT_CN; } -static int -red_requeue(struct sk_buff *skb, struct Qdisc* sch) +static int red_requeue(struct sk_buff *skb, struct Qdisc* sch) { struct red_sched_data *q = qdisc_priv(sch); + struct Qdisc *child = q->qdisc; + int ret; - PSCHED_SET_PASTPERFECT(q->qidlestart); + if (red_is_idling(&q->parms)) + red_end_of_idle_period(&q->parms); - __skb_queue_head(&sch->q, skb); - sch->stats.backlog += skb->len; - return 0; + ret = child->ops->requeue(skb, child); + if (likely(ret == NET_XMIT_SUCCESS)) { + sch->qstats.requeues++; + sch->q.qlen++; + } + return ret; } -static struct sk_buff * -red_dequeue(struct Qdisc* sch) +static struct sk_buff * red_dequeue(struct Qdisc* sch) { struct sk_buff *skb; struct red_sched_data *q = qdisc_priv(sch); + struct Qdisc *child = q->qdisc; - skb = __skb_dequeue(&sch->q); - if (skb) { - sch->stats.backlog -= skb->len; - return skb; - } - PSCHED_GET_TIME(q->qidlestart); - return NULL; + skb = child->dequeue(child); + if (skb) + sch->q.qlen--; + else if (!red_is_idling(&q->parms)) + red_start_of_idle_period(&q->parms); + + return skb; } static unsigned int red_drop(struct Qdisc* sch) { - struct sk_buff *skb; struct red_sched_data *q = qdisc_priv(sch); + struct Qdisc *child = q->qdisc; + unsigned int len; - skb = __skb_dequeue_tail(&sch->q); - if (skb) { - unsigned int len = skb->len; - sch->stats.backlog -= len; - sch->stats.drops++; - q->st.other++; - kfree_skb(skb); + if (child->ops->drop && (len = child->ops->drop(child)) > 0) { + q->stats.other++; + sch->qstats.drops++; + sch->q.qlen--; return len; } - PSCHED_GET_TIME(q->qidlestart); + + if (!red_is_idling(&q->parms)) + red_start_of_idle_period(&q->parms); + return 0; } @@ -349,104 +164,228 @@ static void red_reset(struct Qdisc* sch) { struct red_sched_data *q = qdisc_priv(sch); - __skb_queue_purge(&sch->q); - sch->stats.backlog = 0; - PSCHED_SET_PASTPERFECT(q->qidlestart); - q->qave = 0; - q->qcount = -1; + qdisc_reset(q->qdisc); + sch->q.qlen = 0; + red_restart(&q->parms); +} + +static void red_destroy(struct Qdisc *sch) +{ + struct red_sched_data *q = qdisc_priv(sch); + qdisc_destroy(q->qdisc); +} + +static struct Qdisc *red_create_dflt(struct Qdisc *sch, u32 limit) +{ + struct Qdisc *q; + struct rtattr *rta; + int ret; + + q = qdisc_create_dflt(sch->dev, &bfifo_qdisc_ops, + TC_H_MAKE(sch->handle, 1)); + if (q) { + rta = kmalloc(RTA_LENGTH(sizeof(struct tc_fifo_qopt)), + GFP_KERNEL); + if (rta) { + rta->rta_type = RTM_NEWQDISC; + rta->rta_len = RTA_LENGTH(sizeof(struct tc_fifo_qopt)); + ((struct tc_fifo_qopt *)RTA_DATA(rta))->limit = limit; + + ret = q->ops->change(q, rta); + kfree(rta); + + if (ret == 0) + return q; + } + qdisc_destroy(q); + } + return NULL; } static int red_change(struct Qdisc *sch, struct rtattr *opt) { struct red_sched_data *q = qdisc_priv(sch); - struct rtattr *tb[TCA_RED_STAB]; + struct rtattr *tb[TCA_RED_MAX]; struct tc_red_qopt *ctl; + struct Qdisc *child = NULL; + + if (opt == NULL || rtattr_parse_nested(tb, TCA_RED_MAX, opt)) + return -EINVAL; - if (opt == NULL || - rtattr_parse(tb, TCA_RED_STAB, RTA_DATA(opt), RTA_PAYLOAD(opt)) || - tb[TCA_RED_PARMS-1] == 0 || tb[TCA_RED_STAB-1] == 0 || + if (tb[TCA_RED_PARMS-1] == NULL || RTA_PAYLOAD(tb[TCA_RED_PARMS-1]) < sizeof(*ctl) || - RTA_PAYLOAD(tb[TCA_RED_STAB-1]) < 256) + tb[TCA_RED_STAB-1] == NULL || + RTA_PAYLOAD(tb[TCA_RED_STAB-1]) < RED_STAB_SIZE) return -EINVAL; ctl = RTA_DATA(tb[TCA_RED_PARMS-1]); + if (ctl->limit > 0) { + child = red_create_dflt(sch, ctl->limit); + if (child == NULL) + return -ENOMEM; + } + sch_tree_lock(sch); q->flags = ctl->flags; - q->Wlog = ctl->Wlog; - q->Plog = ctl->Plog; - q->Rmask = ctl->Plog < 32 ? ((1<Plog) - 1) : ~0UL; - q->Scell_log = ctl->Scell_log; - q->Scell_max = (255<Scell_log); - q->qth_min = ctl->qth_min<Wlog; - q->qth_max = ctl->qth_max<Wlog; q->limit = ctl->limit; - memcpy(q->Stab, RTA_DATA(tb[TCA_RED_STAB-1]), 256); + if (child) { + qdisc_tree_decrease_qlen(q->qdisc, q->qdisc->q.qlen); + qdisc_destroy(xchg(&q->qdisc, child)); + } + + red_set_parms(&q->parms, ctl->qth_min, ctl->qth_max, ctl->Wlog, + ctl->Plog, ctl->Scell_log, + RTA_DATA(tb[TCA_RED_STAB-1])); + + if (skb_queue_empty(&sch->q)) + red_end_of_idle_period(&q->parms); - q->qcount = -1; - if (skb_queue_len(&sch->q) == 0) - PSCHED_SET_PASTPERFECT(q->qidlestart); sch_tree_unlock(sch); return 0; } static int red_init(struct Qdisc* sch, struct rtattr *opt) { + struct red_sched_data *q = qdisc_priv(sch); + + q->qdisc = &noop_qdisc; return red_change(sch, opt); } - -int red_copy_xstats(struct sk_buff *skb, struct tc_red_xstats *st) +static int red_dump(struct Qdisc *sch, struct sk_buff *skb) { - RTA_PUT(skb, TCA_XSTATS, sizeof(*st), st); - return 0; + struct red_sched_data *q = qdisc_priv(sch); + struct rtattr *opts = NULL; + struct tc_red_qopt opt = { + .limit = q->limit, + .flags = q->flags, + .qth_min = q->parms.qth_min >> q->parms.Wlog, + .qth_max = q->parms.qth_max >> q->parms.Wlog, + .Wlog = q->parms.Wlog, + .Plog = q->parms.Plog, + .Scell_log = q->parms.Scell_log, + }; + + opts = RTA_NEST(skb, TCA_OPTIONS); + RTA_PUT(skb, TCA_RED_PARMS, sizeof(opt), &opt); + return RTA_NEST_END(skb, opts); rtattr_failure: - return 1; + return RTA_NEST_CANCEL(skb, opts); } -static int red_dump(struct Qdisc *sch, struct sk_buff *skb) +static int red_dump_stats(struct Qdisc *sch, struct gnet_dump *d) { struct red_sched_data *q = qdisc_priv(sch); - unsigned char *b = skb->tail; - struct rtattr *rta; - struct tc_red_qopt opt; - - rta = (struct rtattr*)b; - RTA_PUT(skb, TCA_OPTIONS, 0, NULL); - opt.limit = q->limit; - opt.qth_min = q->qth_min>>q->Wlog; - opt.qth_max = q->qth_max>>q->Wlog; - opt.Wlog = q->Wlog; - opt.Plog = q->Plog; - opt.Scell_log = q->Scell_log; - opt.flags = q->flags; - RTA_PUT(skb, TCA_RED_PARMS, sizeof(opt), &opt); - rta->rta_len = skb->tail - b; + struct tc_red_xstats st = { + .early = q->stats.prob_drop + q->stats.forced_drop, + .pdrop = q->stats.pdrop, + .other = q->stats.other, + .marked = q->stats.prob_mark + q->stats.forced_mark, + }; + + return gnet_stats_copy_app(d, &st, sizeof(st)); +} - if (red_copy_xstats(skb, &q->st)) - goto rtattr_failure; +static int red_dump_class(struct Qdisc *sch, unsigned long cl, + struct sk_buff *skb, struct tcmsg *tcm) +{ + struct red_sched_data *q = qdisc_priv(sch); - return skb->len; + if (cl != 1) + return -ENOENT; + tcm->tcm_handle |= TC_H_MIN(1); + tcm->tcm_info = q->qdisc->handle; + return 0; +} -rtattr_failure: - skb_trim(skb, b - skb->data); - return -1; +static int red_graft(struct Qdisc *sch, unsigned long arg, struct Qdisc *new, + struct Qdisc **old) +{ + struct red_sched_data *q = qdisc_priv(sch); + + if (new == NULL) + new = &noop_qdisc; + + sch_tree_lock(sch); + *old = xchg(&q->qdisc, new); + qdisc_tree_decrease_qlen(*old, (*old)->q.qlen); + qdisc_reset(*old); + sch_tree_unlock(sch); + return 0; } +static struct Qdisc *red_leaf(struct Qdisc *sch, unsigned long arg) +{ + struct red_sched_data *q = qdisc_priv(sch); + return q->qdisc; +} + +static unsigned long red_get(struct Qdisc *sch, u32 classid) +{ + return 1; +} + +static void red_put(struct Qdisc *sch, unsigned long arg) +{ + return; +} + +static int red_change_class(struct Qdisc *sch, u32 classid, u32 parentid, + struct rtattr **tca, unsigned long *arg) +{ + return -ENOSYS; +} + +static int red_delete(struct Qdisc *sch, unsigned long cl) +{ + return -ENOSYS; +} + +static void red_walk(struct Qdisc *sch, struct qdisc_walker *walker) +{ + if (!walker->stop) { + if (walker->count >= walker->skip) + if (walker->fn(sch, 1, walker) < 0) { + walker->stop = 1; + return; + } + walker->count++; + } +} + +static struct tcf_proto **red_find_tcf(struct Qdisc *sch, unsigned long cl) +{ + return NULL; +} + +static struct Qdisc_class_ops red_class_ops = { + .graft = red_graft, + .leaf = red_leaf, + .get = red_get, + .put = red_put, + .change = red_change_class, + .delete = red_delete, + .walk = red_walk, + .tcf_chain = red_find_tcf, + .dump = red_dump_class, +}; + static struct Qdisc_ops red_qdisc_ops = { - .next = NULL, - .cl_ops = NULL, .id = "red", .priv_size = sizeof(struct red_sched_data), + .cl_ops = &red_class_ops, .enqueue = red_enqueue, .dequeue = red_dequeue, .requeue = red_requeue, .drop = red_drop, .init = red_init, .reset = red_reset, + .destroy = red_destroy, .change = red_change, .dump = red_dump, + .dump_stats = red_dump_stats, .owner = THIS_MODULE, }; @@ -454,10 +393,13 @@ static int __init red_module_init(void) { return register_qdisc(&red_qdisc_ops); } -static void __exit red_module_exit(void) + +static void __exit red_module_exit(void) { unregister_qdisc(&red_qdisc_ops); } + module_init(red_module_init) module_exit(red_module_exit) + MODULE_LICENSE("GPL");