From: "Toke Høiland-Jørgensen" <toke@redhat.com>
To: Eric Dumazet <edumazet@google.com>,
"David S . Miller" <davem@davemloft.net>,
Jakub Kicinski <kuba@kernel.org>, Paolo Abeni <pabeni@redhat.com>
Cc: Jamal Hadi Salim <jhs@mojatatu.com>,
Victor Nogueira <victor@mojatatu.com>,
Cong Wang <xiyou.wangcong@gmail.com>,
Jiri Pirko <jiri@resnulli.us>,
netdev@vger.kernel.org, eric.dumazet@gmail.com,
Eric Dumazet <edumazet@google.com>
Subject: Re: [PATCH v2 net-next] net_sched: sch_fq: add three drop_reason
Date: Thu, 05 Dec 2024 12:57:06 +0100 [thread overview]
Message-ID: <875xny9wbx.fsf@toke.dk> (raw)
In-Reply-To: <20241204171950.89829-1-edumazet@google.com>
Eric Dumazet <edumazet@google.com> writes:
> 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_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_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_FLOW_LIMIT
> Whenever a flow has reached its limit.
> Corresponding value in "tc -s qd" is flows_plimit XXXX
>
> Tested:
> tc qd replace dev eth1 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_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_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_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_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_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_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_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_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_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_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@google.com>
Nice to see qdisc-specific drop reasons - guess I should look at this
for sch_cake as well!
Reviewed-by: Toke Høiland-Jørgensen <toke@redhat.com>
next prev parent reply other threads:[~2024-12-05 11:57 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-12-04 17:19 [PATCH v2 net-next] net_sched: sch_fq: add three drop_reason Eric Dumazet
2024-12-05 1:07 ` Victor Nogueira
2024-12-05 11:57 ` Toke Høiland-Jørgensen [this message]
2024-12-05 12:41 ` Jamal Hadi Salim
2024-12-08 2:43 ` Jakub Kicinski
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