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netem: add uapi to express delay and jitter in nanoseconds 

netem userspace has long relied on a horrible /proc/net/psched hack
to translate the current notion of "ticks" to nanoseconds.

Expressing latency and jitter instead, in well defined nanoseconds,
increases the dynamic range of emulated delays and jitter in netem.

It will also ease a transition where reducing a tick to nsec
equivalence would constrain the max delay in prior versions of
netem to only 4.3 seconds.

Signed-off-by: Dave Taht <dave.taht@gmail.com>
Suggested-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Dave Taht 2017-11-08 15:12:27 -08:00 committed by David S. Miller
parent 112f9cb656
commit 99803171ef
2 changed files with 16 additions and 0 deletions
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2
include/uapi/linux/pkt_sched.h
View File

@ -537,6 +537,8 @@ enum {
TCA_NETEM_ECN,
TCA_NETEM_RATE64,
TCA_NETEM_PAD,
TCA_NETEM_LATENCY64,
TCA_NETEM_JITTER64,
__TCA_NETEM_MAX,
};

14
net/sched/sch_netem.c
View File

@ -819,6 +819,8 @@ static const struct nla_policy netem_policy[TCA_NETEM_MAX + 1] = {
[TCA_NETEM_LOSS] = { .type = NLA_NESTED },
[TCA_NETEM_ECN] = { .type = NLA_U32 },
[TCA_NETEM_RATE64] = { .type = NLA_U64 },
[TCA_NETEM_LATENCY64] = { .type = NLA_S64 },
[TCA_NETEM_JITTER64] = { .type = NLA_S64 },
};
static int parse_attr(struct nlattr *tb[], int maxtype, struct nlattr *nla,
@ -916,6 +918,12 @@ static int netem_change(struct Qdisc *sch, struct nlattr *opt)
q->rate = max_t(u64, q->rate,
nla_get_u64(tb[TCA_NETEM_RATE64]));
if (tb[TCA_NETEM_LATENCY64])
q->latency = nla_get_s64(tb[TCA_NETEM_LATENCY64]);
if (tb[TCA_NETEM_JITTER64])
q->jitter = nla_get_s64(tb[TCA_NETEM_JITTER64]);
if (tb[TCA_NETEM_ECN])
q->ecn = nla_get_u32(tb[TCA_NETEM_ECN]);
@ -1020,6 +1028,12 @@ static int netem_dump(struct Qdisc *sch, struct sk_buff *skb)
if (nla_put(skb, TCA_OPTIONS, sizeof(qopt), &qopt))
goto nla_put_failure;
if (nla_put(skb, TCA_NETEM_LATENCY64, sizeof(q->latency), &q->latency))
goto nla_put_failure;
if (nla_put(skb, TCA_NETEM_JITTER64, sizeof(q->jitter), &q->jitter))
goto nla_put_failure;
cor.delay_corr = q->delay_cor.rho;
cor.loss_corr = q->loss_cor.rho;
cor.dup_corr = q->dup_cor.rho;