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Message-ID: <20230815092348.1449179-4-francois.michel@uclouvain.be>
Date: Tue, 15 Aug 2023 11:23:40 +0200
From: Francois Michel <francois.michel@...ouvain.be>
To: unlisted-recipients:; (no To-header on input)
Cc: Francois Michel <francois.michel@...ouvain.be>,
Jamal Hadi Salim <jhs@...atatu.com>,
Cong Wang <xiyou.wangcong@...il.com>,
Jiri Pirko <jiri@...nulli.us>,
Stephen Hemminger <stephen@...workplumber.org>,
"David S. Miller" <davem@...emloft.net>,
Eric Dumazet <edumazet@...gle.com>,
Jakub Kicinski <kuba@...nel.org>,
Paolo Abeni <pabeni@...hat.com>, netdev@...r.kernel.org,
linux-kernel@...r.kernel.org
Subject: [PATCH v2 net-next 3/3] netem: use seeded PRNG for correlated loss events
From: François Michel <francois.michel@...ouvain.be>
Use prandom_u32_state() instead of get_random_u32() to generate
the correlated loss events of netem.
Signed-off-by: François Michel <francois.michel@...ouvain.be>
---
net/sched/sch_netem.c | 22 ++++++++++++----------
1 file changed, 12 insertions(+), 10 deletions(-)
diff --git a/net/sched/sch_netem.c b/net/sched/sch_netem.c
index 8b54b1005a10..4ad39a4a3cf5 100644
--- a/net/sched/sch_netem.c
+++ b/net/sched/sch_netem.c
@@ -184,15 +184,16 @@ static void init_crandom(struct crndstate *state, unsigned long rho)
* Next number depends on last value.
* rho is scaled to avoid floating point.
*/
-static u32 get_crandom(struct crndstate *state)
+static u32 get_crandom(struct crndstate *state, struct prng *p)
{
u64 value, rho;
unsigned long answer;
+ struct rnd_state *s = &p->prng_state;
if (!state || state->rho == 0) /* no correlation */
- return get_random_u32();
+ return prandom_u32_state(s);
- value = get_random_u32();
+ value = prandom_u32_state(s);
rho = (u64)state->rho + 1;
answer = (value * ((1ull<<32) - rho) + state->last * rho) >> 32;
state->last = answer;
@@ -295,7 +296,7 @@ static bool loss_event(struct netem_sched_data *q)
switch (q->loss_model) {
case CLG_RANDOM:
/* Random packet drop 0 => none, ~0 => all */
- return q->loss && q->loss >= get_crandom(&q->loss_cor);
+ return q->loss && q->loss >= get_crandom(&q->loss_cor, &q->prng);
case CLG_4_STATES:
/* 4state loss model algorithm (used also for GI model)
@@ -324,6 +325,7 @@ static bool loss_event(struct netem_sched_data *q)
*/
static s64 tabledist(s64 mu, s32 sigma,
struct crndstate *state,
+ struct prng *prng,
const struct disttable *dist)
{
s64 x;
@@ -333,7 +335,7 @@ static s64 tabledist(s64 mu, s32 sigma,
if (sigma == 0)
return mu;
- rnd = get_crandom(state);
+ rnd = get_crandom(state, prng);
/* default uniform distribution */
if (dist == NULL)
@@ -455,7 +457,7 @@ static int netem_enqueue(struct sk_buff *skb, struct Qdisc *sch,
skb->prev = NULL;
/* Random duplication */
- if (q->duplicate && q->duplicate >= get_crandom(&q->dup_cor))
+ if (q->duplicate && q->duplicate >= get_crandom(&q->dup_cor, &q->prng))
++count;
/* Drop packet? */
@@ -498,7 +500,7 @@ static int netem_enqueue(struct sk_buff *skb, struct Qdisc *sch,
* If packet is going to be hardware checksummed, then
* do it now in software before we mangle it.
*/
- if (q->corrupt && q->corrupt >= get_crandom(&q->corrupt_cor)) {
+ if (q->corrupt && q->corrupt >= get_crandom(&q->corrupt_cor, &q->prng)) {
if (skb_is_gso(skb)) {
skb = netem_segment(skb, sch, to_free);
if (!skb)
@@ -536,12 +538,12 @@ static int netem_enqueue(struct sk_buff *skb, struct Qdisc *sch,
cb = netem_skb_cb(skb);
if (q->gap == 0 || /* not doing reordering */
q->counter < q->gap - 1 || /* inside last reordering gap */
- q->reorder < get_crandom(&q->reorder_cor)) {
+ q->reorder < get_crandom(&q->reorder_cor, &q->prng)) {
u64 now;
s64 delay;
delay = tabledist(q->latency, q->jitter,
- &q->delay_cor, q->delay_dist);
+ &q->delay_cor, &q->prng, q->delay_dist);
now = ktime_get_ns();
@@ -645,7 +647,7 @@ static void get_slot_next(struct netem_sched_data *q, u64 now)
else
next_delay = tabledist(q->slot_config.dist_delay,
(s32)(q->slot_config.dist_jitter),
- NULL, q->slot_dist);
+ NULL, &q->prng, q->slot_dist);
q->slot.slot_next = now + next_delay;
q->slot.packets_left = q->slot_config.max_packets;
--
2.41.0
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