net: sched: tbf: fix the calculation of max_size
Current max_size is caluated from rate table. Now, the rate table has been replaced and it's wrong to caculate max_size based on this rate table. It can lead wrong calculation of max_size. The burst in kernel may be lower than user asked, because burst may gets some loss when transform it to buffer(E.g. "burst 40kb rate 30mbit/s") and it seems we cannot avoid this loss. Burst's value(max_size) based on rate table may be equal user asked. If a packet's length is max_size, this packet will be stalled in tbf_dequeue() because its length is above the burst in kernel so that it cannot get enough tokens. The max_size guards against enqueuing packet sizes above q->buffer "time" in tbf_enqueue(). To make consistent with the calculation of tokens, this patch add a helper psched_ns_t2l() to calculate burst(max_size) directly to fix this problem. After this fix, we can support to using 64bit rates to calculate burst as well. Signed-off-by: Yang Yingliang <yangyingliang@huawei.com> Acked-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
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4bd7b5127b
Коммит
cc106e441a
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@ -118,6 +118,30 @@ struct tbf_sched_data {
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};
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/* Time to Length, convert time in ns to length in bytes
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* to determinate how many bytes can be sent in given time.
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*/
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static u64 psched_ns_t2l(const struct psched_ratecfg *r,
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u64 time_in_ns)
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{
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/* The formula is :
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* len = (time_in_ns * r->rate_bytes_ps) / NSEC_PER_SEC
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*/
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u64 len = time_in_ns * r->rate_bytes_ps;
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do_div(len, NSEC_PER_SEC);
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if (unlikely(r->linklayer == TC_LINKLAYER_ATM))
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len = (len / 53) * 48;
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if (len > r->overhead)
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len -= r->overhead;
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else
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len = 0;
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return len;
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}
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/*
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* Return length of individual segments of a gso packet,
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* including all headers (MAC, IP, TCP/UDP)
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@ -289,10 +313,11 @@ static int tbf_change(struct Qdisc *sch, struct nlattr *opt)
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struct tbf_sched_data *q = qdisc_priv(sch);
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struct nlattr *tb[TCA_TBF_MAX + 1];
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struct tc_tbf_qopt *qopt;
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struct qdisc_rate_table *rtab = NULL;
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struct qdisc_rate_table *ptab = NULL;
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struct Qdisc *child = NULL;
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int max_size, n;
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struct psched_ratecfg rate;
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struct psched_ratecfg peak;
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u64 max_size;
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s64 buffer, mtu;
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u64 rate64 = 0, prate64 = 0;
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err = nla_parse_nested(tb, TCA_TBF_MAX, opt, tbf_policy);
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@ -304,38 +329,13 @@ static int tbf_change(struct Qdisc *sch, struct nlattr *opt)
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goto done;
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qopt = nla_data(tb[TCA_TBF_PARMS]);
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rtab = qdisc_get_rtab(&qopt->rate, tb[TCA_TBF_RTAB]);
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if (rtab == NULL)
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goto done;
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if (qopt->rate.linklayer == TC_LINKLAYER_UNAWARE)
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qdisc_put_rtab(qdisc_get_rtab(&qopt->rate,
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tb[TCA_TBF_RTAB]));
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if (qopt->peakrate.rate) {
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if (qopt->peakrate.rate > qopt->rate.rate)
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ptab = qdisc_get_rtab(&qopt->peakrate, tb[TCA_TBF_PTAB]);
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if (ptab == NULL)
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goto done;
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}
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for (n = 0; n < 256; n++)
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if (rtab->data[n] > qopt->buffer)
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break;
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max_size = (n << qopt->rate.cell_log) - 1;
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if (ptab) {
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int size;
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for (n = 0; n < 256; n++)
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if (ptab->data[n] > qopt->mtu)
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break;
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size = (n << qopt->peakrate.cell_log) - 1;
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if (size < max_size)
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max_size = size;
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}
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if (max_size < 0)
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goto done;
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if (max_size < psched_mtu(qdisc_dev(sch)))
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pr_warn_ratelimited("sch_tbf: burst %u is lower than device %s mtu (%u) !\n",
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max_size, qdisc_dev(sch)->name,
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psched_mtu(qdisc_dev(sch)));
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if (qopt->peakrate.linklayer == TC_LINKLAYER_UNAWARE)
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qdisc_put_rtab(qdisc_get_rtab(&qopt->peakrate,
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tb[TCA_TBF_PTAB]));
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if (q->qdisc != &noop_qdisc) {
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err = fifo_set_limit(q->qdisc, qopt->limit);
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@ -349,6 +349,39 @@ static int tbf_change(struct Qdisc *sch, struct nlattr *opt)
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}
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}
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buffer = min_t(u64, PSCHED_TICKS2NS(qopt->buffer), ~0U);
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mtu = min_t(u64, PSCHED_TICKS2NS(qopt->mtu), ~0U);
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if (tb[TCA_TBF_RATE64])
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rate64 = nla_get_u64(tb[TCA_TBF_RATE64]);
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psched_ratecfg_precompute(&rate, &qopt->rate, rate64);
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max_size = min_t(u64, psched_ns_t2l(&rate, buffer), ~0U);
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if (qopt->peakrate.rate) {
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if (tb[TCA_TBF_PRATE64])
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prate64 = nla_get_u64(tb[TCA_TBF_PRATE64]);
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psched_ratecfg_precompute(&peak, &qopt->peakrate, prate64);
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if (peak.rate_bytes_ps <= rate.rate_bytes_ps) {
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pr_warn_ratelimited("sch_tbf: peakrate %llu is lower than or equals to rate %llu !\n",
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peak.rate_bytes_ps, rate.rate_bytes_ps);
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err = -EINVAL;
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goto done;
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}
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max_size = min_t(u64, max_size, psched_ns_t2l(&peak, mtu));
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}
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if (max_size < psched_mtu(qdisc_dev(sch)))
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pr_warn_ratelimited("sch_tbf: burst %llu is lower than device %s mtu (%u) !\n",
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max_size, qdisc_dev(sch)->name,
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psched_mtu(qdisc_dev(sch)));
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if (!max_size) {
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err = -EINVAL;
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goto done;
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}
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sch_tree_lock(sch);
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if (child) {
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qdisc_tree_decrease_qlen(q->qdisc, q->qdisc->q.qlen);
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@ -362,13 +395,9 @@ static int tbf_change(struct Qdisc *sch, struct nlattr *opt)
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q->tokens = q->buffer;
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q->ptokens = q->mtu;
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if (tb[TCA_TBF_RATE64])
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rate64 = nla_get_u64(tb[TCA_TBF_RATE64]);
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psched_ratecfg_precompute(&q->rate, &rtab->rate, rate64);
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if (ptab) {
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if (tb[TCA_TBF_PRATE64])
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prate64 = nla_get_u64(tb[TCA_TBF_PRATE64]);
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psched_ratecfg_precompute(&q->peak, &ptab->rate, prate64);
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memcpy(&q->rate, &rate, sizeof(struct psched_ratecfg));
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if (qopt->peakrate.rate) {
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memcpy(&q->peak, &peak, sizeof(struct psched_ratecfg));
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q->peak_present = true;
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} else {
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q->peak_present = false;
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@ -377,10 +406,6 @@ static int tbf_change(struct Qdisc *sch, struct nlattr *opt)
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sch_tree_unlock(sch);
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err = 0;
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done:
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if (rtab)
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qdisc_put_rtab(rtab);
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if (ptab)
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qdisc_put_rtab(ptab);
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return err;
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}
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