diff mbox series

[v2,net-next,2/3] netem: add uapi to express delay and jitter in nanoseconds

Message ID 1510175399-7404-3-git-send-email-dave.taht@gmail.com
State Superseded, archived
Delegated to: David Miller
Headers show
Series netem: add nsec scheduling and slot feature | expand

Commit Message

Dave Taht Nov. 8, 2017, 9:09 p.m. UTC 
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>
---
 include/uapi/linux/pkt_sched.h |  2 ++
 net/sched/sch_netem.c          | 14 ++++++++++++++
 2 files changed, 16 insertions(+)

Comments

Eric Dumazet Nov. 8, 2017, 10:29 p.m. UTC | #1 
On Wed, 2017-11-08 at 13:09 -0800, Dave Taht wrote:
> 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>
diff mbox series

Patch

diff --git a/include/uapi/linux/pkt_sched.h b/include/uapi/linux/pkt_sched.h
index 6a2c5ea..8fe6d18 100644
--- a/include/uapi/linux/pkt_sched.h
+++ b/include/uapi/linux/pkt_sched.h
@@ -537,6 +537,8 @@  enum {
 	TCA_NETEM_ECN,
 	TCA_NETEM_RATE64,
 	TCA_NETEM_PAD,
+	TCA_NETEM_LATENCY64,
+	TCA_NETEM_JITTER64,
 	__TCA_NETEM_MAX,
 };
 
diff --git a/net/sched/sch_netem.c b/net/sched/sch_netem.c
index 5559ad1..ef63ae4 100644
--- a/net/sched/sch_netem.c
+++ b/net/sched/sch_netem.c
@@ -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;