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>

diff --git a/include/uapi/linux/pkt_sched.h b/include/uapi/linux/pkt_sched.h
index 6a2c5ea7e9c4e04264ddd80de963dc7ba1f8fede..8fe6d1842bee5c74b74e84e2bf36f3ccfb8bfc49 100644 (file)
--- 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 e64e0e0d94ff3121bc09d802f4457eed0be142e7..47d6decba0ea66294ef0b946706cbd75a63ced38 100644 (file)
--- 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;