From: Yang Yingliang <yangyingliang@huawei•com>
To: Eric Dumazet <eric.dumazet@gmail•com>
Cc: netdev <netdev@vger•kernel.org>, <davem@davemloft•net>,
<brouer@redhat•com>, <jpirko@redhat•com>, <jbrouer@redhat•com>
Subject: [PATCH] net: sched: tbf: fix calculation of max_size
Date: Mon, 25 Nov 2013 20:04:23 +0800 [thread overview]
Message-ID: <52933CC7.9070805@huawei.com> (raw)
In-Reply-To: <5292C76E.1070701@huawei.com>
From: Yang Yingliang <yangyingliang@huawei•com>
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. And 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().
This patch fixes the calculation of max_size by using psched_l2t_ns() and
q->buffer to recalculate burst(max_size).
Also, add support to get burst from userland directly. We can avoid loss
in byte-to-time transform by using burst directly. Iproute2 will need a
patch to send burst to kernel.
Suggested-by: Jesper Dangaard Brouer <jbrouer@redhat•com>
Signed-off-by: Yang Yingliang <yangyingliang@huawei•com>
---
include/uapi/linux/pkt_sched.h | 2 +
net/sched/sch_tbf.c | 110 ++++++++++++++++++++++++++---------------
2 files changed, 72 insertions(+), 40 deletions(-)
diff --git a/include/uapi/linux/pkt_sched.h b/include/uapi/linux/pkt_sched.h
index 307f293..b5a0976 100644
--- a/include/uapi/linux/pkt_sched.h
+++ b/include/uapi/linux/pkt_sched.h
@@ -173,6 +173,8 @@ enum {
TCA_TBF_PTAB,
TCA_TBF_RATE64,
TCA_TBF_PRATE64,
+ TCA_TBF_BURST,
+ TCA_TBF_PBURST,
__TCA_TBF_MAX,
};
diff --git a/net/sched/sch_tbf.c b/net/sched/sch_tbf.c
index a609005..3d01bf0 100644
--- a/net/sched/sch_tbf.c
+++ b/net/sched/sch_tbf.c
@@ -281,8 +281,12 @@ static const struct nla_policy tbf_policy[TCA_TBF_MAX + 1] = {
[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 },
};
+#define MAX_PKT_LEN 65535
+
static int tbf_change(struct Qdisc *sch, struct nlattr *opt)
{
int err;
@@ -292,7 +296,7 @@ static int tbf_change(struct Qdisc *sch, struct nlattr *opt)
struct qdisc_rate_table *rtab = NULL;
struct qdisc_rate_table *ptab = NULL;
struct Qdisc *child = NULL;
- int max_size, n;
+ int max_size;
u64 rate64 = 0, prate64 = 0;
err = nla_parse_nested(tb, TCA_TBF_MAX, opt, tbf_policy);
@@ -304,38 +308,20 @@ static int tbf_change(struct Qdisc *sch, struct nlattr *opt)
goto done;
qopt = nla_data(tb[TCA_TBF_PARMS]);
- rtab = qdisc_get_rtab(&qopt->rate, tb[TCA_TBF_RTAB]);
- if (rtab == NULL)
- goto done;
-
- if (qopt->peakrate.rate) {
- if (qopt->peakrate.rate > qopt->rate.rate)
- ptab = qdisc_get_rtab(&qopt->peakrate, tb[TCA_TBF_PTAB]);
- if (ptab == NULL)
- goto done;
+ if (qopt->rate.linklayer == TC_LINKLAYER_UNAWARE) {
+ rtab = qdisc_get_rtab(&qopt->rate, tb[TCA_TBF_RTAB]);
+ if (rtab) {
+ qdisc_put_rtab(rtab);
+ rtab = NULL;
+ }
}
-
- for (n = 0; n < 256; n++)
- if (rtab->data[n] > qopt->buffer)
- break;
- max_size = (n << qopt->rate.cell_log) - 1;
- if (ptab) {
- int size;
-
- for (n = 0; n < 256; n++)
- if (ptab->data[n] > qopt->mtu)
- break;
- size = (n << qopt->peakrate.cell_log) - 1;
- if (size < max_size)
- max_size = size;
+ if (qopt->peakrate.linklayer == TC_LINKLAYER_UNAWARE) {
+ ptab = qdisc_get_rtab(&qopt->peakrate, tb[TCA_TBF_PTAB]);
+ if (ptab) {
+ qdisc_put_rtab(ptab);
+ ptab = NULL;
+ }
}
- if (max_size < 0)
- goto done;
-
- if (max_size < psched_mtu(qdisc_dev(sch)))
- pr_warn_ratelimited("sch_tbf: burst %u is lower than device %s mtu (%u) !\n",
- max_size, qdisc_dev(sch)->name,
- psched_mtu(qdisc_dev(sch)));
if (q->qdisc != &noop_qdisc) {
err = fifo_set_limit(q->qdisc, qopt->limit);
@@ -357,30 +343,74 @@ static int tbf_change(struct Qdisc *sch, struct nlattr *opt)
}
q->limit = qopt->limit;
q->mtu = PSCHED_TICKS2NS(qopt->mtu);
- q->max_size = max_size;
q->buffer = PSCHED_TICKS2NS(qopt->buffer);
q->tokens = q->buffer;
q->ptokens = q->mtu;
if (tb[TCA_TBF_RATE64])
rate64 = nla_get_u64(tb[TCA_TBF_RATE64]);
- psched_ratecfg_precompute(&q->rate, &rtab->rate, rate64);
- if (ptab) {
+ psched_ratecfg_precompute(&q->rate, &qopt->rate, rate64);
+ if (!q->rate.rate_bytes_ps)
+ goto unlock_done;
+
+ if (tb[TCA_TBF_BURST]) {
+ u32 burst = nla_get_u32(tb[TCA_TBF_BURST]);
+ q->buffer = psched_l2t_ns(&q->rate, burst);
+ max_size = min_t(u32, burst, MAX_PKT_LEN);
+ } else {
+ for (max_size = 0; max_size < MAX_PKT_LEN; max_size++)
+ if (psched_l2t_ns(&q->rate, max_size) > q->buffer)
+ break;
+ max_size--;
+ if (max_size < 0)
+ goto unlock_done;
+ }
+
+ if (qopt->peakrate.rate) {
+ int size = 0;
if (tb[TCA_TBF_PRATE64])
prate64 = nla_get_u64(tb[TCA_TBF_PRATE64]);
- psched_ratecfg_precompute(&q->peak, &ptab->rate, prate64);
+ psched_ratecfg_precompute(&q->peak, &qopt->peakrate, prate64);
+ if (q->peak.rate_bytes_ps <= q->rate.rate_bytes_ps) {
+ pr_err("Rate must be lower than peakrate!\n");
+ goto unlock_done;
+ }
+
+ if (tb[TCA_TBF_PBURST]) {
+ u32 pburst = nla_get_u32(tb[TCA_TBF_PBURST]);
+ q->mtu = psched_l2t_ns(&q->peak, pburst);
+ size = min_t(u32, pburst, MAX_PKT_LEN);
+ } else {
+ for (size = 0; size < MAX_PKT_LEN; size++)
+ if (psched_l2t_ns(&q->peak, size) > q->mtu)
+ break;
+ size--;
+ if (size < 0)
+ goto unlock_done;
+ }
+ max_size = min_t(u32, max_size, size);
q->peak_present = true;
} else {
q->peak_present = false;
}
+ if (!max_size)
+ goto unlock_done;
+
+ if (max_size < psched_mtu(qdisc_dev(sch)))
+ pr_warn_ratelimited("sch_tbf: burst %u is lower than device %s mtu (%u) !\n",
+ max_size, qdisc_dev(sch)->name,
+ psched_mtu(qdisc_dev(sch)));
+
+ q->max_size = max_size;
+
sch_tree_unlock(sch);
- err = 0;
+ return 0;
+
+unlock_done:
+ sch_tree_unlock(sch);
+ err = -EINVAL;
done:
- if (rtab)
- qdisc_put_rtab(rtab);
- if (ptab)
- qdisc_put_rtab(ptab);
return err;
}
-- 1.8.0
next prev parent reply other threads:[~2013-11-25 12:04 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-11-19 7:25 [PATCH net v3 0/2] net: sched: fix some issues Yang Yingliang
2013-11-19 7:25 ` [PATCH net v3 1/2] net: sched: tbf: fix calculation of max_size Yang Yingliang
2013-11-19 9:38 ` Jesper Dangaard Brouer
2013-11-20 2:14 ` Yang Yingliang
2013-11-20 10:04 ` Jesper Dangaard Brouer
2013-11-20 12:50 ` Yang Yingliang
2013-11-23 19:06 ` Eric Dumazet
2013-11-24 7:28 ` Yang Yingliang
2013-11-24 18:40 ` Eric Dumazet
2013-11-25 3:43 ` Yang Yingliang
2013-11-25 12:04 ` Yang Yingliang [this message]
2013-11-25 12:22 ` [PATCH] " David Laight
2013-11-26 1:28 ` Yang Yingliang
2013-11-26 2:35 ` Yang Yingliang
2013-12-02 1:11 ` David Miller
2013-12-02 10:29 ` David Laight
2013-12-02 16:45 ` David Miller
2013-12-03 0:59 ` Yang Yingliang
2013-11-19 7:25 ` [PATCH net v3 2/2] net: sched: htb: fix calculation of quantum Yang Yingliang
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