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Message-ID: <20241203210929.3281461-1-edumazet@google.com>
Date: Tue, 3 Dec 2024 21:09:29 +0000
From: Eric Dumazet <edumazet@...gle.com>
To: "David S . Miller" <davem@...emloft.net>, Jakub Kicinski <kuba@...nel.org>,
Paolo Abeni <pabeni@...hat.com>
Cc: Jamal Hadi Salim <jhs@...atatu.com>, Victor Nogueira <victor@...atatu.com>,
Cong Wang <xiyou.wangcong@...il.com>, Jiri Pirko <jiri@...nulli.us>, netdev@...r.kernel.org,
eric.dumazet@...il.com, Eric Dumazet <edumazet@...gle.com>
Subject: [PATCH net-next] net_sched: sch_fq: add three drop_reason
Add three new drop_reason, more precise than generic QDISC_DROP:
"tc -s qd" show aggregate counters, it might be more useful
to use drop_reason infrastructure for bug hunting.
1) SKB_DROP_REASON_FQ_DROP_BAND_LIMIT
Whenever a packet is added while its band limit is hit.
Corresponding value in "tc -s qd" is bandX_drops XXXX
2) SKB_DROP_REASON_FQ_DROP_HORIZON_LIMIT
Whenever a packet has a timestamp too far in the future.
Corresponding value in "tc -s qd" is horizon_drops XXXX
3) SKB_DROP_REASON_FQ_DROP_FLOW_LIMIT
Whenever a flow has reached its limit.
Corresponding value in "tc -s qd" is flows_plimit XXXX
Tested:
tc qd replace dev eth0 root fq flow_limit 10 limit 100000
perf record -a -e skb:kfree_skb sleep 1; perf script
udp_stream 12329 [004] 216.929492: skb:kfree_skb: skbaddr=0xffff888eabe17e00 rx_sk=(nil) protocol=34525 location=__dev_queue_xmit+0x9d9 reason: FQ_DROP_FLOW_LIMIT
udp_stream 12385 [006] 216.929593: skb:kfree_skb: skbaddr=0xffff888ef8827f00 rx_sk=(nil) protocol=34525 location=__dev_queue_xmit+0x9d9 reason: FQ_DROP_FLOW_LIMIT
udp_stream 12389 [005] 216.929871: skb:kfree_skb: skbaddr=0xffff888ecb9ba500 rx_sk=(nil) protocol=34525 location=__dev_queue_xmit+0x9d9 reason: FQ_DROP_FLOW_LIMIT
udp_stream 12316 [009] 216.930398: skb:kfree_skb: skbaddr=0xffff888eca286b00 rx_sk=(nil) protocol=34525 location=__dev_queue_xmit+0x9d9 reason: FQ_DROP_FLOW_LIMIT
udp_stream 12400 [008] 216.930490: skb:kfree_skb: skbaddr=0xffff888eabf93d00 rx_sk=(nil) protocol=34525 location=__dev_queue_xmit+0x9d9 reason: FQ_DROP_FLOW_LIMIT
tc qd replace dev eth1 root fq flow_limit 100 limit 10000
perf record -a -e skb:kfree_skb sleep 1; perf script
udp_stream 18074 [001] 1058.318040: skb:kfree_skb: skbaddr=0xffffa23c881fc000 rx_sk=(nil) protocol=34525 location=__dev_queue_xmit+0x9d9 reason: FQ_DROP_BAND_LIMIT
udp_stream 18126 [005] 1058.320651: skb:kfree_skb: skbaddr=0xffffa23c6aad4000 rx_sk=(nil) protocol=34525 location=__dev_queue_xmit+0x9d9 reason: FQ_DROP_BAND_LIMIT
udp_stream 18118 [006] 1058.321065: skb:kfree_skb: skbaddr=0xffffa23df0d48a00 rx_sk=(nil) protocol=34525 location=__dev_queue_xmit+0x9d9 reason: FQ_DROP_BAND_LIMIT
udp_stream 18074 [001] 1058.321126: skb:kfree_skb: skbaddr=0xffffa23c881ffa00 rx_sk=(nil) protocol=34525 location=__dev_queue_xmit+0x9d9 reason: FQ_DROP_BAND_LIMIT
udp_stream 15815 [003] 1058.321224: skb:kfree_skb: skbaddr=0xffffa23c9835db00 rx_sk=(nil) protocol=34525 location=__dev_queue_xmit+0x9d9 reason: FQ_DROP_BAND_LIMIT
tc -s -d qd sh dev eth1
qdisc fq 8023: root refcnt 257 limit 10000p flow_limit 100p buckets 1024 orphan_mask 1023
bands 3 priomap 1 2 2 2 1 2 0 0 1 1 1 1 1 1 1 1 weights 589824 196608 65536 quantum 18Kb
initial_quantum 92120b low_rate_threshold 550Kbit refill_delay 40ms
timer_slack 10us horizon 10s horizon_drop
Sent 492439603330 bytes 336953991 pkt (dropped 61724094, overlimits 0 requeues 4463)
backlog 14611228b 9995p requeues 4463
flows 2965 (inactive 1151 throttled 0) band0_pkts 0 band1_pkts 9993 band2_pkts 0
gc 6347 highprio 0 fastpath 30 throttled 5 latency 2.32us flows_plimit 7403693
band1_drops 54320401
Signed-off-by: Eric Dumazet <edumazet@...gle.com>
---
include/net/dropreason-core.h | 18 ++++++++++++++++++
include/net/sch_generic.h | 9 +++++++++
net/sched/sch_fq.c | 14 ++++++++++----
3 files changed, 37 insertions(+), 4 deletions(-)
diff --git a/include/net/dropreason-core.h b/include/net/dropreason-core.h
index 6c5a1ea209a22d8702f8c982762ca5f69791b8eb..570605152a2a2d36a698aa062104d59d3aba000b 100644
--- a/include/net/dropreason-core.h
+++ b/include/net/dropreason-core.h
@@ -58,6 +58,9 @@
FN(TC_EGRESS) \
FN(SECURITY_HOOK) \
FN(QDISC_DROP) \
+ FN(FQ_DROP_BAND_LIMIT) \
+ FN(FQ_DROP_HORIZON_LIMIT) \
+ FN(FQ_DROP_FLOW_LIMIT) \
FN(CPU_BACKLOG) \
FN(XDP) \
FN(TC_INGRESS) \
@@ -311,6 +314,21 @@ enum skb_drop_reason {
* failed to enqueue to current qdisc)
*/
SKB_DROP_REASON_QDISC_DROP,
+ /**
+ * @SKB_DROP_REASON_FQ_DROP_BAND_LIMIT: dropped by fq qdisc when per band
+ * limit is reached.
+ */
+ SKB_DROP_REASON_FQ_DROP_BAND_LIMIT,
+ /**
+ * @SKB_DROP_REASON_FQ_DROP_HORIZON_LIMIT: dropped by fq qdisc when packet
+ * timestamp is too far in the future.
+ */
+ SKB_DROP_REASON_FQ_DROP_HORIZON_LIMIT,
+ /**
+ * @SKB_DROP_REASON_FQ_DROP_FLOW_LIMIT: dropped by fq qdisc when a flow
+ * exceeds its limits.
+ */
+ SKB_DROP_REASON_FQ_DROP_FLOW_LIMIT,
/**
* @SKB_DROP_REASON_CPU_BACKLOG: failed to enqueue the skb to the per CPU
* backlog queue. This can be caused by backlog queue full (see
diff --git a/include/net/sch_generic.h b/include/net/sch_generic.h
index 5d74fa7e694cc85be91dbf01f0876b9feaa29115..c7a33c2c69830a6cbff8f6359de7cc468c2e845e 100644
--- a/include/net/sch_generic.h
+++ b/include/net/sch_generic.h
@@ -1245,6 +1245,15 @@ static inline int qdisc_drop(struct sk_buff *skb, struct Qdisc *sch,
return NET_XMIT_DROP;
}
+static inline int qdisc_drop_reason(struct sk_buff *skb, struct Qdisc *sch,
+ struct sk_buff **to_free,
+ enum skb_drop_reason reason)
+{
+ tcf_set_drop_reason(skb, reason);
+ return qdisc_drop(skb, sch, to_free);
+}
+
+
static inline int qdisc_drop_all(struct sk_buff *skb, struct Qdisc *sch,
struct sk_buff **to_free)
{
diff --git a/net/sched/sch_fq.c b/net/sched/sch_fq.c
index a5e87f9ea9861cbedb7ce858fbbcabb5d67cf821..9180810e39fa230ee2c4b6b94bcb87df388f4df8 100644
--- a/net/sched/sch_fq.c
+++ b/net/sched/sch_fq.c
@@ -537,6 +537,8 @@ static bool fq_packet_beyond_horizon(const struct sk_buff *skb,
return unlikely((s64)skb->tstamp > (s64)(now + q->horizon));
}
+#define FQDR(reason) SKB_DROP_REASON_FQ_DROP_##reason
+
static int fq_enqueue(struct sk_buff *skb, struct Qdisc *sch,
struct sk_buff **to_free)
{
@@ -548,7 +550,8 @@ static int fq_enqueue(struct sk_buff *skb, struct Qdisc *sch,
band = fq_prio2band(q->prio2band, skb->priority & TC_PRIO_MAX);
if (unlikely(q->band_pkt_count[band] >= sch->limit)) {
q->stat_band_drops[band]++;
- return qdisc_drop(skb, sch, to_free);
+ return qdisc_drop_reason(skb, sch, to_free,
+ FQDR(BAND_LIMIT));
}
now = ktime_get_ns();
@@ -558,8 +561,9 @@ static int fq_enqueue(struct sk_buff *skb, struct Qdisc *sch,
/* Check if packet timestamp is too far in the future. */
if (fq_packet_beyond_horizon(skb, q, now)) {
if (q->horizon_drop) {
- q->stat_horizon_drops++;
- return qdisc_drop(skb, sch, to_free);
+ q->stat_horizon_drops++;
+ return qdisc_drop_reason(skb, sch, to_free,
+ FQDR(HORIZON_LIMIT));
}
q->stat_horizon_caps++;
skb->tstamp = now + q->horizon;
@@ -572,7 +576,8 @@ static int fq_enqueue(struct sk_buff *skb, struct Qdisc *sch,
if (f != &q->internal) {
if (unlikely(f->qlen >= q->flow_plimit)) {
q->stat_flows_plimit++;
- return qdisc_drop(skb, sch, to_free);
+ return qdisc_drop_reason(skb, sch, to_free,
+ FQDR(FLOW_LIMIT));
}
if (fq_flow_is_detached(f)) {
@@ -597,6 +602,7 @@ static int fq_enqueue(struct sk_buff *skb, struct Qdisc *sch,
return NET_XMIT_SUCCESS;
}
+#undef FQDR
static void fq_check_throttled(struct fq_sched_data *q, u64 now)
{
--
2.47.0.338.g60cca15819-goog
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