Commit 99803171 authored by Dave Taht's avatar Dave Taht Committed by David S. Miller
Browse files

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: default avatarDave Taht <dave.taht@gmail.com>
Suggested-by: default avatarEric Dumazet <edumazet@google.com>
Reviewed-by: default avatarEric Dumazet <edumazet@google.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 112f9cb6

include/uapi/linux/pkt_sched.h

+2 −0
Original line number Diff line number Diff line
@@ -537,6 +537,8 @@ enum { 
	TCA_NETEM_ECN,

	TCA_NETEM_RATE64,

	TCA_NETEM_PAD,

	TCA_NETEM_LATENCY64,

	TCA_NETEM_JITTER64,

	__TCA_NETEM_MAX,

};

net/sched/sch_netem.c

+14 −0
Original line number Diff line number Diff line
@@ -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;

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