cregit-Linux how code gets into the kernel

Release 4.8 net/sched/sch_tbf.c

Directory: net/sched
 * net/sched/sch_tbf.c  Token Bucket Filter queue.
 *              This program is free software; you can redistribute it and/or
 *              modify it under the terms of the GNU General Public License
 *              as published by the Free Software Foundation; either version
 *              2 of the License, or (at your option) any later version.
 * Authors:     Alexey Kuznetsov, <>
 *              Dmitry Torokhov <> - allow attaching inner qdiscs -
 *                                               original idea by Martin Devera

#include <linux/module.h>
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/string.h>
#include <linux/errno.h>
#include <linux/skbuff.h>
#include <net/netlink.h>
#include <net/sch_generic.h>
#include <net/pkt_sched.h>

/*      Simple Token Bucket Filter.




        A data flow obeys TBF with rate R and depth B, if for any
        time interval t_i...t_f the number of transmitted bits
        does not exceed B + R*(t_f-t_i).

        Packetized version of this definition:
        The sequence of packets of sizes s_i served at moments t_i
        obeys TBF, if for any i<=k:

        s_i+....+s_k <= B + R*(t_k - t_i)


        Let N(t_i) be B/R initially and N(t) grow continuously with time as:

        N(t+delta) = min{B/R, N(t) + delta}

        If the first packet in queue has length S, it may be
        transmitted only at the time t_* when S/R <= N(t_*),
        and in this case N(t) jumps:

        N(t_* + 0) = N(t_* - 0) - S/R.

        Actually, QoS requires two TBF to be applied to a data stream.
        One of them controls steady state burst size, another
        one with rate P (peak rate) and depth M (equal to link MTU)
        limits bursts at a smaller time scale.

        It is easy to see that P>R, and B>M. If P is infinity, this double
        TBF is equivalent to a single one.

        When TBF works in reshaping mode, latency is estimated as:

        lat = max ((L-B)/R, (L-M)/P)


        If TBF throttles, it starts a watchdog timer, which will wake it up
        when it is ready to transmit.
        Note that the minimal timer resolution is 1/HZ.
        If no new packets arrive during this period,
        or if the device is not awaken by EOI for some previous packet,
        TBF can stop its activity for 1/HZ.

        This means, that with depth B, the maximal rate is

        R_crit = B*HZ

        F.e. for 10Mbit ethernet and HZ=100 the minimal allowed B is ~10Kbytes.

        Note that the peak rate TBF is much more tough: with MTU 1500
        P_crit = 150Kbytes/sec. So, if you need greater peak
        rates, use alpha with HZ=1000 :-)

        With classful TBF, limit is just kept for backwards compatibility.
        It is passed to the default bfifo qdisc - if the inner qdisc is
        changed the limit is not effective anymore.

struct tbf_sched_data {
/* Parameters */
u32		limit;		/* Maximal length of backlog: bytes */
u32		max_size;
s64		buffer;		/* Token bucket depth/rate: MUST BE >= MTU/B */
s64		mtu;
struct psched_ratecfg rate;
struct psched_ratecfg peak;

/* Variables */
s64	tokens;			/* Current number of B tokens */
s64	ptokens;		/* Current number of P tokens */
s64	t_c;			/* Time check-point */
struct Qdisc	*qdisc;		/* Inner qdisc, default - bfifo queue */
struct qdisc_watchdog watchdog;	/* Watchdog timer */

/* Time to Length, convert time in ns to length in bytes
 * to determinate how many bytes can be sent in given time.

static u64 psched_ns_t2l(const struct psched_ratecfg *r, u64 time_in_ns) { /* The formula is : * len = (time_in_ns * r->rate_bytes_ps) / NSEC_PER_SEC */ u64 len = time_in_ns * r->rate_bytes_ps; do_div(len, NSEC_PER_SEC); if (unlikely(r->linklayer == TC_LINKLAYER_ATM)) { do_div(len, 53); len = len * 48; } if (len > r->overhead) len -= r->overhead; else len = 0; return len; }


yang yingliangyang yingliang80100.00%2100.00%

/* * Return length of individual segments of a gso packet, * including all headers (MAC, IP, TCP/UDP) */
static unsigned int skb_gso_mac_seglen(const struct sk_buff *skb) { unsigned int hdr_len = skb_transport_header(skb) - skb_mac_header(skb); return hdr_len + skb_gso_transport_seglen(skb); }


eric dumazeteric dumazet3188.57%150.00%
florian westphalflorian westphal411.43%150.00%

/* GSO packet is too big, segment it so that tbf can transmit * each segment in time */
static int tbf_segment(struct sk_buff *skb, struct Qdisc *sch, struct sk_buff **to_free) { struct tbf_sched_data *q = qdisc_priv(sch); struct sk_buff *segs, *nskb; netdev_features_t features = netif_skb_features(skb); unsigned int len = 0, prev_len = qdisc_pkt_len(skb); int ret, nb; segs = skb_gso_segment(skb, features & ~NETIF_F_GSO_MASK); if (IS_ERR_OR_NULL(segs)) return qdisc_drop(skb, sch, to_free); nb = 0; while (segs) { nskb = segs->next; segs->next = NULL; qdisc_skb_cb(segs)->pkt_len = segs->len; len += segs->len; ret = qdisc_enqueue(segs, q->qdisc, to_free); if (ret != NET_XMIT_SUCCESS) { if (net_xmit_drop_count(ret)) qdisc_qstats_drop(sch); } else { nb++; } segs = nskb; } sch->q.qlen += nb; if (nb > 1) qdisc_tree_reduce_backlog(sch, 1 - nb, prev_len - len); consume_skb(skb); return nb > 0 ? NET_XMIT_SUCCESS : NET_XMIT_DROP; }


eric dumazeteric dumazet19087.16%240.00%
americo wangamerico wang2411.01%120.00%
john fastabendjohn fastabend31.38%120.00%
florian westphalflorian westphal10.46%120.00%

static int tbf_enqueue(struct sk_buff *skb, struct Qdisc *sch, struct sk_buff **to_free) { struct tbf_sched_data *q = qdisc_priv(sch); int ret; if (qdisc_pkt_len(skb) > q->max_size) { if (skb_is_gso(skb) && skb_gso_mac_seglen(skb) <= q->max_size) return tbf_segment(skb, sch, to_free); return qdisc_drop(skb, sch, to_free); } ret = qdisc_enqueue(skb, q->qdisc, to_free); if (ret != NET_XMIT_SUCCESS) { if (net_xmit_drop_count(ret)) qdisc_qstats_drop(sch); return ret; } qdisc_qstats_backlog_inc(sch, skb); sch->q.qlen++; return NET_XMIT_SUCCESS; }


eric dumazeteric dumazet3727.01%317.65%
dmitry torokhovdmitry torokhov2518.25%15.88%
jussi kivilinnajussi kivilinna85.84%211.76%
americo wangamerico wang75.11%15.88%
jarek poplawskijarek poplawski75.11%15.88%
stephen hemmingerstephen hemminger32.19%15.88%
john fastabendjohn fastabend32.19%15.88%
ben greearben greear21.46%15.88%
florian westphalflorian westphal21.46%211.76%
david s. millerdavid s. miller10.73%15.88%

static bool tbf_peak_present(const struct tbf_sched_data *q) { return q->peak.rate_bytes_ps; }


hiroaki shimodahiroaki shimoda19100.00%1100.00%

static struct sk_buff *tbf_dequeue(struct Qdisc *sch) { struct tbf_sched_data *q = qdisc_priv(sch); struct sk_buff *skb; skb = q->qdisc->ops->peek(q->qdisc); if (skb) { s64 now; s64 toks; s64 ptoks = 0; unsigned int len = qdisc_pkt_len(skb); now = ktime_get_ns(); toks = min_t(s64, now - q->t_c, q->buffer); if (tbf_peak_present(q)) { ptoks = toks + q->ptokens; if (ptoks > q->mtu) ptoks = q->mtu; ptoks -= (s64) psched_l2t_ns(&q->peak, len); } toks += q->tokens; if (toks > q->buffer) toks = q->buffer; toks -= (s64) psched_l2t_ns(&q->rate, len); if ((toks|ptoks) >= 0) { skb = qdisc_dequeue_peeked(q->qdisc); if (unlikely(!skb)) return NULL; q->t_c = now; q->tokens = toks; q->ptokens = ptoks; qdisc_qstats_backlog_dec(sch, skb); sch->q.qlen--; qdisc_bstats_update(sch, skb); return skb; } qdisc_watchdog_schedule_ns(&q->watchdog, now + max_t(long, -toks, -ptoks)); /* Maybe we have a shorter packet in the queue, which can be sent now. It sounds cool, but, however, this is wrong in principle. We MUST NOT reorder packets under these circumstances. Really, if we split the flow into independent subflows, it would be a very good solution. This is the main idea of all FQ algorithms (cf. CSZ, HPFQ, HFSC) */ qdisc_qstats_overlimit(sch); } return NULL; }


jarek poplawskijarek poplawski238.33%210.53%
jiri pirkojiri pirko227.97%15.26%
dmitry torokhovdmitry torokhov176.16%15.26%
patrick mchardypatrick mchardy93.26%210.53%
eric dumazeteric dumazet82.90%210.53%
americo wangamerico wang72.54%15.26%
linus torvaldslinus torvalds31.09%210.53%
hiroaki shimodahiroaki shimoda31.09%15.26%
stephen hemmingerstephen hemminger31.09%15.26%
jussi kivilinnajussi kivilinna31.09%15.26%
john fastabendjohn fastabend31.09%15.26%
david s. millerdavid s. miller10.36%15.26%

static void tbf_reset(struct Qdisc *sch) { struct tbf_sched_data *q = qdisc_priv(sch); qdisc_reset(q->qdisc); sch->qstats.backlog = 0; sch->q.qlen = 0; q->t_c = ktime_get_ns(); q->tokens = q->buffer; q->ptokens = q->mtu; qdisc_watchdog_cancel(&q->watchdog); }


patrick mchardypatrick mchardy810.67%337.50%
americo wangamerico wang810.67%112.50%
dmitry torokhovdmitry torokhov79.33%112.50%
stephen hemmingerstephen hemminger34.00%112.50%
eric dumazeteric dumazet11.33%112.50%

static const struct nla_policy tbf_policy[TCA_TBF_MAX + 1] = { [TCA_TBF_PARMS] = { .len = sizeof(struct tc_tbf_qopt) }, [TCA_TBF_RTAB] = { .type = NLA_BINARY, .len = TC_RTAB_SIZE }, [TCA_TBF_PTAB] = { .type = NLA_BINARY, .len = TC_RTAB_SIZE }, [TCA_TBF_RATE64] = { .type = NLA_U64 }, [TCA_TBF_PRATE64] = { .type = NLA_U64 }, [TCA_TBF_BURST] = { .type = NLA_U32 }, [TCA_TBF_PBURST] = { .type = NLA_U32 }, };
static int tbf_change(struct Qdisc *sch, struct nlattr *opt) { int err; struct tbf_sched_data *q = qdisc_priv(sch); struct nlattr *tb[TCA_TBF_MAX + 1]; struct tc_tbf_qopt *qopt; struct Qdisc *child = NULL; struct psched_ratecfg rate; struct psched_ratecfg peak; u64 max_size; s64 buffer, mtu; u64 rate64 = 0, prate64 = 0; err = nla_parse_nested(tb, TCA_TBF_MAX, opt, tbf_policy); if (err < 0) return err; err = -EINVAL; if (tb[TCA_TBF_PARMS] == NULL) goto done; qopt = nla_data(tb[TCA_TBF_PARMS]); if (qopt->rate.linklayer == TC_LINKLAYER_UNAWARE) qdisc_put_rtab(qdisc_get_rtab(&qopt->rate, tb[TCA_TBF_RTAB])); if (qopt->peakrate.linklayer == TC_LINKLAYER_UNAWARE) qdisc_put_rtab(qdisc_get_rtab(&qopt->peakrate, tb[TCA_TBF_PTAB])); buffer = min_t(u64, PSCHED_TICKS2NS(qopt->buffer), ~0U); mtu = min_t(u64, PSCHED_TICKS2NS(qopt->mtu), ~0U); if (tb[TCA_TBF_RATE64]) rate64 = nla_get_u64(tb[TCA_TBF_RATE64]); psched_ratecfg_precompute(&rate, &qopt->rate, rate64); if (tb[TCA_TBF_BURST]) { max_size = nla_get_u32(tb[TCA_TBF_BURST]); buffer = psched_l2t_ns(&rate, max_size); } else { max_size = min_t(u64, psched_ns_t2l(&rate, buffer), ~0U); } if (qopt->peakrate.rate) { if (tb[TCA_TBF_PRATE64]) prate64 = nla_get_u64(tb[TCA_TBF_PRATE64]); psched_ratecfg_precompute(&peak, &qopt->peakrate, prate64); if (peak.rate_bytes_ps <= rate.rate_bytes_ps) { pr_warn_ratelimited("sch_tbf: peakrate %llu is lower than or equals to rate %llu !\n", peak.rate_bytes_ps, rate.rate_bytes_ps); err = -EINVAL; goto done; } if (tb[TCA_TBF_PBURST]) { u32 pburst = nla_get_u32(tb[TCA_TBF_PBURST]); max_size = min_t(u32, max_size, pburst); mtu = psched_l2t_ns(&peak, pburst); } else { max_size = min_t(u64, max_size, psched_ns_t2l(&peak, mtu)); } } else { memset(&peak, 0, sizeof(peak)); } if (max_size < psched_mtu(qdisc_dev(sch))) pr_warn_ratelimited("sch_tbf: burst %llu is lower than device %s mtu (%u) !\n", max_size, qdisc_dev(sch)->name, psched_mtu(qdisc_dev(sch))); if (!max_size) { err = -EINVAL; goto done; } if (q->qdisc != &noop_qdisc) { err = fifo_set_limit(q->qdisc, qopt->limit); if (err) goto done; } else if (qopt->limit > 0) { child = fifo_create_dflt(sch, &bfifo_qdisc_ops, qopt->limit); if (IS_ERR(child)) { err = PTR_ERR(child); goto done; } } sch_tree_lock(sch); if (child) { qdisc_tree_reduce_backlog(q->qdisc, q->qdisc->q.qlen, q->qdisc->qstats.backlog); qdisc_destroy(q->qdisc); q->qdisc = child; } q->limit = qopt->limit; if (tb[TCA_TBF_PBURST]) q->mtu = mtu; else q->mtu = PSCHED_TICKS2NS(qopt->mtu); q->max_size = max_size; if (tb[TCA_TBF_BURST]) q->buffer = buffer; else q->buffer = PSCHED_TICKS2NS(qopt->buffer); q->tokens = q->buffer; q->ptokens = q->mtu; memcpy(&q->rate, &rate, sizeof(struct psched_ratecfg)); memcpy(&q->peak, &peak, sizeof(struct psched_ratecfg)); sch_tree_unlock(sch); err = 0; done: return err; }


yang yingliangyang yingliang31342.30%312.00%
hiroaki shimodahiroaki shimoda9112.30%28.00%
patrick mchardypatrick mchardy618.24%728.00%
eric dumazeteric dumazet375.00%312.00%
dmitry torokhovdmitry torokhov172.30%14.00%
jiri pirkojiri pirko111.49%14.00%
americo wangamerico wang91.22%14.00%
linus torvaldslinus torvalds81.08%14.00%
ilpo jarvinenilpo jarvinen60.81%14.00%
stephen hemmingerstephen hemminger30.41%14.00%

static int tbf_init(struct Qdisc *sch, struct nlattr *opt) { struct tbf_sched_data *q = qdisc_priv(sch); if (opt == NULL) return -EINVAL; q->t_c = ktime_get_ns(); qdisc_watchdog_init(&q->watchdog, sch); q->qdisc = &noop_qdisc; return tbf_change(sch, opt); }


dmitry torokhovdmitry torokhov710.29%111.11%
patrick mchardypatrick mchardy710.29%333.33%
stephen hemmingerstephen hemminger34.41%111.11%
eric dumazeteric dumazet11.47%111.11%
david s. millerdavid s. miller11.47%111.11%

static void tbf_destroy(struct Qdisc *sch) { struct tbf_sched_data *q = qdisc_priv(sch); qdisc_watchdog_cancel(&q->watchdog); qdisc_destroy(q->qdisc); }


dmitry torokhovdmitry torokhov719.44%120.00%
stephen hemmingerstephen hemminger38.33%120.00%
patrick mchardypatrick mchardy25.56%120.00%

static int tbf_dump(struct Qdisc *sch, struct sk_buff *skb) { struct tbf_sched_data *q = qdisc_priv(sch); struct nlattr *nest; struct tc_tbf_qopt opt; sch->qstats.backlog = q->qdisc->qstats.backlog; nest = nla_nest_start(skb, TCA_OPTIONS); if (nest == NULL) goto nla_put_failure; opt.limit = q->limit; psched_ratecfg_getrate(&opt.rate, &q->rate); if (tbf_peak_present(q)) psched_ratecfg_getrate(&opt.peakrate, &q->peak); else memset(&opt.peakrate, 0, sizeof(opt.peakrate)); opt.mtu = PSCHED_NS2TICKS(q->mtu); opt.buffer = PSCHED_NS2TICKS(q->buffer); if (nla_put(skb, TCA_TBF_PARMS, sizeof(opt), &opt)) goto nla_put_failure; if (q->rate.rate_bytes_ps >= (1ULL << 32) && nla_put_u64_64bit(skb, TCA_TBF_RATE64, q->rate.rate_bytes_ps, TCA_TBF_PAD)) goto nla_put_failure; if (tbf_peak_present(q) && q->peak.rate_bytes_ps >= (1ULL << 32) && nla_put_u64_64bit(skb, TCA_TBF_PRATE64, q->peak.rate_bytes_ps, TCA_TBF_PAD)) goto nla_put_failure; return nla_nest_end(skb, nest); nla_put_failure: nla_nest_cancel(skb, nest); return -1; }


yang yingliangyang yingliang6123.64%214.29%
eric dumazeteric dumazet228.53%214.29%
patrick mchardypatrick mchardy197.36%214.29%
jiri pirkojiri pirko114.26%17.14%
david s. millerdavid s. miller72.71%17.14%
nicolas dichtelnicolas dichtel62.33%17.14%
hiroaki shimodahiroaki shimoda62.33%17.14%
stephen hemmingerstephen hemminger31.16%17.14%
arnaldo carvalho de meloarnaldo carvalho de melo20.78%17.14%

static int tbf_dump_class(struct Qdisc *sch, unsigned long cl, struct sk_buff *skb, struct tcmsg *tcm) { struct tbf_sched_data *q = qdisc_priv(sch); tcm->tcm_handle |= TC_H_MIN(1); tcm->tcm_info = q->qdisc->handle; return 0; }


dmitry torokhovdmitry torokhov5291.23%250.00%
stephen hemmingerstephen hemminger35.26%125.00%

static int tbf_graft(struct Qdisc *sch, unsigned long arg, struct Qdisc *new, struct Qdisc **old) { struct tbf_sched_data *q = qdisc_priv(sch); if (new == NULL) new = &noop_qdisc; *old = qdisc_replace(sch, new, &q->qdisc); return 0; }


dmitry torokhovdmitry torokhov5280.00%116.67%
americo wangamerico wang710.77%116.67%
stephen hemmingerstephen hemminger34.62%116.67%
patrick mchardypatrick mchardy23.08%233.33%

static struct Qdisc *tbf_leaf(struct Qdisc *sch, unsigned long arg) { struct tbf_sched_data *q = qdisc_priv(sch); return q->qdisc; }


dmitry torokhovdmitry torokhov2990.62%150.00%
stephen hemmingerstephen hemminger39.38%150.00%

static unsigned long tbf_get(struct Qdisc *sch, u32 classid) { return 1; }


dmitry torokhovdmitry torokhov18100.00%1100.00%

static void tbf_put(struct Qdisc *sch, unsigned long arg) { }


dmitry torokhovdmitry torokhov14100.00%1100.00%

static void tbf_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++; } }


dmitry torokhovdmitry torokhov64100.00%2100.00%

static const struct Qdisc_class_ops tbf_class_ops = { .graft = tbf_graft, .leaf = tbf_leaf, .get = tbf_get, .put = tbf_put, .walk = tbf_walk, .dump = tbf_dump_class, }; static struct Qdisc_ops tbf_qdisc_ops __read_mostly = { .next = NULL, .cl_ops = &tbf_class_ops, .id = "tbf", .priv_size = sizeof(struct tbf_sched_data), .enqueue = tbf_enqueue, .dequeue = tbf_dequeue, .peek = qdisc_peek_dequeued, .init = tbf_init, .reset = tbf_reset, .destroy = tbf_destroy, .change = tbf_change, .dump = tbf_dump, .owner = THIS_MODULE, };
static int __init tbf_module_init(void) { return register_qdisc(&tbf_qdisc_ops); }


al viroal viro318.75%133.33%

static void __exit tbf_module_exit(void) { unregister_qdisc(&tbf_qdisc_ops); }


al viroal viro320.00%133.33%

module_init(tbf_module_init) module_exit(tbf_module_exit) MODULE_LICENSE("GPL");

Overall Contributors

yang yingliangyang yingliang49919.65%57.81%
dmitry torokhovdmitry torokhov37414.72%34.69%
eric dumazeteric dumazet33113.03%914.06%
patrick mchardypatrick mchardy1746.85%1320.31%
hiroaki shimodahiroaki shimoda1224.80%23.12%
americo wangamerico wang622.44%34.69%
jiri pirkojiri pirko572.24%11.56%
jarek poplawskijarek poplawski351.38%34.69%
stephen hemmingerstephen hemminger301.18%11.56%
dave jonesdave jones271.06%11.56%
linus torvaldslinus torvalds170.67%57.81%
al viroal viro150.59%11.56%
jussi kivilinnajussi kivilinna110.43%23.12%
david s. millerdavid s. miller100.39%46.25%
john fastabendjohn fastabend90.35%11.56%
florian westphalflorian westphal70.28%23.12%
ilpo jarvinenilpo jarvinen60.24%11.56%
nicolas dichtelnicolas dichtel60.24%11.56%
ben greearben greear20.08%11.56%
arnaldo carvalho de meloarnaldo carvalho de melo20.08%11.56%
Directory: net/sched
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