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DualPI2 provides L4S-type low latency & loss to traffic that uses a
scalable congestion controller (e.g. TCP-Prague, DCTCP) without
degrading the performance of 'classic' traffic (e.g. Reno,
Cubic etc.). It is to be the reference implementation of IETF RFC9332
DualQ Coupled AQM (https://datatracker.ietf.org/doc/html/rfc9332).
Note that creating two independent queues cannot meet the goal of
DualPI2 mentioned in RFC9332: "...to preserve fairness between
ECN-capable and non-ECN-capable traffic." Further, it could even
lead to starvation of Classic traffic, which is also inconsistent
with the requirements in RFC9332: "...although priority MUST be
bounded in order not to starve Classic traffic." DualPI2 is
designed to maintain approximate per-flow fairness on L-queue and
C-queue by forming a single qdisc using the coupling factor and
scheduler between two queues.
The qdisc provides two queues called low latency and classic. It
classifies packets based on the ECN field in the IP headers. By
default it directs non-ECN and ECT(0) into the classic queue and
ECT(1) and CE into the low latency queue, as per the IETF spec.
Each queue runs its own AQM:
* The classic AQM is called PI2, which is similar to the PIE AQM but
more responsive and simpler. Classic traffic requires a decent
target queue (default 15ms for Internet deployment) to fully
utilize the link and to avoid high drop rates.
* The low latency AQM is, by default, a very shallow ECN marking
threshold (1ms) similar to that used for DCTCP.
The DualQ isolates the low queuing delay of the Low Latency queue
from the larger delay of the 'Classic' queue. However, from a
bandwidth perspective, flows in either queue will share out the link
capacity as if there was just a single queue. This bandwidth pooling
effect is achieved by coupling together the drop and ECN-marking
probabilities of the two AQMs.
The PI2 AQM has two main parameters in addition to its target delay.
The integral gain factor alpha is used to slowly correct any persistent
standing queue error from the target delay, while the proportional gain
factor beta is used to quickly compensate for queue changes (growth or
shrinkage). Either alpha and beta are given as a parameter, or they can
be calculated by tc from alternative typical and maximum RTT parameters.
Internally, the output of a linear Proportional Integral (PI)
controller is used for both queues. This output is squared to
calculate the drop or ECN-marking probability of the classic queue.
This counterbalances the square-root rate equation of Reno/Cubic,
which is the trick that balances flow rates across the queues. For
the ECN-marking probability of the low latency queue, the output of
the base AQM is multiplied by a coupling factor. This determines the
balance between the flow rates in each queue. The default setting
makes the flow rates roughly equal, which should be generally
applicable.
If DUALPI2 AQM has detected overload (due to excessive non-responsive
traffic in either queue), it will switch to signaling congestion
solely using drop, irrespective of the ECN field. Alternatively, it
can be configured to limit the drop probability and let the queue
grow and eventually overflow (like tail-drop).
GSO splitting in DUALPI2 is configurable from userspace while the
default behavior is to split gso. When running DUALPI2 at unshaped
10gigE with 4 download streams test, splitting gso apart results in
halving the latency with no loss in throughput:
Summary of tcp_4down run 'no_split_gso':
avg median # data pts
Ping (ms) ICMP : 0.53 0.30 ms 350
TCP download avg : 2326.86 N/A Mbits/s 350
TCP download sum : 9307.42 N/A Mbits/s 350
TCP download::1 : 2672.99 2568.73 Mbits/s 350
TCP download::2 : 2586.96 2570.51 Mbits/s 350
TCP download::3 : 1786.26 1798.82 Mbits/s 350
TCP download::4 : 2261.21 2309.49 Mbits/s 350
Summart of tcp_4down run 'split_gso':
avg median # data pts
Ping (ms) ICMP : 0.22 0.23 ms 350
TCP download avg : 2335.02 N/A Mbits/s 350
TCP download sum : 9340.09 N/A Mbits/s 350
TCP download::1 : 2335.30 2334.22 Mbits/s 350
TCP download::2 : 2334.72 2334.20 Mbits/s 350
TCP download::3 : 2335.28 2334.58 Mbits/s 350
TCP download::4 : 2334.79 2334.39 Mbits/s 350
A similar result is observed when running DUALPI2 at unshaped 1gigE
with 1 download stream test:
Summary of tcp_1down run 'no_split_gso':
avg median # data pts
Ping (ms) ICMP : 1.13 1.25 ms 350
TCP download : 941.41 941.46 Mbits/s 350
Summart of tcp_1down run 'split_gso':
avg median # data pts
Ping (ms) ICMP : 0.51 0.55 ms 350
TCP download : 941.41 941.45 Mbits/s 350
Additional details can be found in the draft:
https://datatracker.ietf.org/doc/html/rfc9332
Signed-off-by: Koen De Schepper <koen.de_schepper@nokia-bell-labs.com>
Co-developed-by: Olga Albisser <olga@albisser.org>
Signed-off-by: Olga Albisser <olga@albisser.org>
Co-developed-by: Olivier Tilmans <olivier.tilmans@nokia.com>
Signed-off-by: Olivier Tilmans <olivier.tilmans@nokia.com>
Co-developed-by: Henrik Steen <henrist@henrist.net>
Signed-off-by: Henrik Steen <henrist@henrist.net>
Co-developed-by: Chia-Yu Chang <chia-yu.chang@nokia-bell-labs.com>
Signed-off-by: Chia-Yu Chang <chia-yu.chang@nokia-bell-labs.com>
Signed-off-by: Bob Briscoe <research@bobbriscoe.net>
Signed-off-by: Ilpo Järvinen <ij@kernel.org>
Acked-by: Dave Taht <dave.taht@gmail.com>
Link: https://patch.msgid.link/20250722095915.24485-4-chia-yu.chang@nokia-bell-labs.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
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Add a new SKB drop reason (SKB_DROP_REASON_PFMEMALLOC) to track packets
dropped due to memory pressure. In production environments, we've observed
memory exhaustion reported by memory layer stack traces, but these drops
were not properly tracked in the SKB drop reason infrastructure.
While most network code paths now properly report pfmemalloc drops, some
protocol-specific socket implementations still use sk_filter() without
drop reason tracking:
- Bluetooth L2CAP sockets
- CAIF sockets
- IUCV sockets
- Netlink sockets
- SCTP sockets
- Unix domain sockets
These remaining cases represent less common paths and could be converted
in a follow-up patch if needed. The current implementation provides
significantly improved observability into memory pressure events in the
network stack, especially for key protocols like TCP and UDP, helping to
diagnose problems in production environments.
Reported-by: Matt Fleming <mfleming@cloudflare.com>
Signed-off-by: Jesper Dangaard Brouer <hawk@kernel.org>
Link: https://patch.msgid.link/175268316579.2407873.11634752355644843509.stgit@firesoul
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
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Add a new SNMP MIB : LINUX_MIB_BEYOND_WINDOW
Incremented when an incoming packet is received beyond the
receiver window.
nstat -az | grep TcpExtBeyondWindow
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Kuniyuki Iwashima <kuniyu@google.com>
Link: https://patch.msgid.link/20250711114006.480026-3-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
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Currently, TCP accepts incoming packets which might go beyond the
offered RWIN.
Add to tcp_sequence() the validation of packet end sequence.
Add the corresponding check in the fast path.
We relax this new constraint if the receive queue is empty,
to not freeze flows from buggy peers.
Add a new drop reason : SKB_DROP_REASON_TCP_INVALID_END_SEQUENCE.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Kuniyuki Iwashima <kuniyu@google.com>
Link: https://patch.msgid.link/20250711114006.480026-2-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
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Besides the existing pr_warn_once(), use skb drop reasons in case AF_CAN
layer drops non-conformant CAN{,FD,XL} frames, or conformant frames
received by "wrong" devices, so that it's possible to debug (and count)
such events using existing tracepoints:
| # perf record -e skb:kfree_skb -aR -- ./drv/canfdtest -v -g -l 1 vcan0
| # perf script
| [...]
| canfdtest 1123 [000] 3893.271264: skb:kfree_skb: skbaddr=0xffff975703c9f700 rx_sk=(nil) protocol=12 location=can_rcv+0x4b reason: CAN_RX_INVALID_FRAME
Signed-off-by: Davide Caratti <dcaratti@redhat.com>
Link: https://patch.msgid.link/20250604160605.1005704-2-dcaratti@redhat.com
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
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neigh_connected_output()
Replace kfree_skb() used in neigh_resolve_output() and
neigh_connected_output() with kfree_skb_reason().
Following new skb drop reason is added:
/* failed to fill the device hard header */
SKB_DROP_REASON_NEIGH_HH_FILLFAIL
Signed-off-by: Qiu Yutan <qiu.yutan@zte.com.cn>
Signed-off-by: Jiang Kun <jiang.kun2@zte.com.cn>
Reviewed-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Reviewed-by: Xu Xin <xu.xin16@zte.com.cn>
Signed-off-by: David S. Miller <davem@davemloft.net>
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When TCP is in TIME_WAIT state, PAWS verification uses
LINUX_PAWSESTABREJECTED, which is ambiguous and cannot be distinguished
from other PAWS verification processes.
We added a new counter, like the existing PAWS_OLD_ACK one.
Also we update the doc with previously missing PAWS_OLD_ACK.
usage:
'''
nstat -az | grep PAWSTimewait
TcpExtPAWSTimewait 1 0.0
'''
Suggested-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Jiayuan Chen <jiayuan.chen@linux.dev>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Link: https://patch.msgid.link/20250409112614.16153-3-jiayuan.chen@linux.dev
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
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Devices in the networking path, such as firewalls, NATs, or routers, which
can perform SNAT or DNAT, use addresses from their own limited address
pools to masquerade the source address during forwarding, causing PAWS
verification to fail more easily.
Currently, packet loss statistics for PAWS can only be viewed through MIB,
which is a global metric and cannot be precisely obtained through tracing
to get the specific 4-tuple of the dropped packet. In the past, we had to
use kprobe ret to retrieve relevant skb information from
tcp_timewait_state_process().
We add a drop_reason pointer, similar to what previous commit does:
commit e34100c2ecbb ("tcp: add a drop_reason pointer to tcp_check_req()")
This commit addresses the PAWSESTABREJECTED case and also sets the
corresponding drop reason.
We use 'pwru' to test.
Before this commit:
''''
./pwru 'port 9999'
2025/04/07 13:40:19 Listening for events..
TUPLE FUNC
172.31.75.115:12345->172.31.75.114:9999(tcp) sk_skb_reason_drop(SKB_DROP_REASON_NOT_SPECIFIED)
'''
After this commit:
'''
./pwru 'port 9999'
2025/04/07 13:51:34 Listening for events..
TUPLE FUNC
172.31.75.115:12345->172.31.75.114:9999(tcp) sk_skb_reason_drop(SKB_DROP_REASON_TCP_RFC7323_TW_PAWS)
'''
Suggested-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Jiayuan Chen <jiayuan.chen@linux.dev>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Link: https://patch.msgid.link/20250409112614.16153-2-jiayuan.chen@linux.dev
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
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Use two existing drop reasons in tcp_check_req():
- TCP_RFC7323_PAWS
- TCP_OVERWINDOW
Add two new ones:
- TCP_RFC7323_TSECR (corresponds to LINUX_MIB_TSECRREJECTED)
- TCP_LISTEN_OVERFLOW (when a listener accept queue is full)
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Jason Xing <kerneljasonxing@gmail.com>
Reviewed-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Link: https://patch.msgid.link/20250301201424.2046477-3-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
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unix_dgram_disconnected() is called from two places:
1. when a connect()ed socket dis-connect()s or re-connect()s to
another socket
2. when sendmsg() fails because the peer socket that the client
has connect()ed to has been close()d
Then, the client's recv queue is purged to remove all messages from
the old peer socket.
Let's define a new drop reason for that case.
# echo 1 > /sys/kernel/tracing/events/skb/kfree_skb/enable
# python3
>>> from socket import *
>>>
>>> # s1 has a message from s2
>>> s1, s2 = socketpair(AF_UNIX, SOCK_DGRAM)
>>> s2.send(b'hello world')
>>>
>>> # re-connect() drops the message from s2
>>> s3 = socket(AF_UNIX, SOCK_DGRAM)
>>> s3.bind('')
>>> s1.connect(s3.getsockname())
# cat /sys/kernel/tracing/trace_pipe
python3-250 ... kfree_skb: ... location=skb_queue_purge_reason+0xdc/0x110 reason: UNIX_DISCONNECT
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Link: https://patch.msgid.link/20250116053441.5758-8-kuniyu@amazon.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
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AF_UNIX SOCK_STREAM socket supports MSG_OOB.
When OOB data is sent to a socket, recv() will break at that point.
If the next recv() does not have MSG_OOB, the normal data following
the OOB data is returned.
Then, the OOB skb is dropped.
Let's define a new drop reason for that case in manage_oob().
# echo 1 > /sys/kernel/tracing/events/skb/kfree_skb/enable
# python3
>>> from socket import *
>>> s1, s2 = socketpair(AF_UNIX)
>>> s1.send(b'a', MSG_OOB)
>>> s1.send(b'b')
>>> s2.recv(2)
b'b'
# cat /sys/kernel/tracing/trace_pipe
...
python3-223 ... kfree_skb: ... location=unix_stream_read_generic+0x59e/0xc20 reason: UNIX_SKIP_OOB
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Link: https://patch.msgid.link/20250116053441.5758-6-kuniyu@amazon.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
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unix_release_sock() is called when the last refcnt of struct file
is released.
Let's define a new drop reason SKB_DROP_REASON_SOCKET_CLOSE and
set it for kfree_skb() in unix_release_sock().
# echo 1 > /sys/kernel/tracing/events/skb/kfree_skb/enable
# python3
>>> from socket import *
>>> s1, s2 = socketpair(AF_UNIX)
>>> s1.send(b'hello world')
>>> s2.close()
# cat /sys/kernel/tracing/trace_pipe
...
python3-280 ... kfree_skb: ... protocol=0 location=unix_release_sock+0x260/0x420 reason: SOCKET_CLOSE
To be precise, unix_release_sock() is also called for a new child
socket in unix_stream_connect() when something fails, but the new
sk does not have skb in the recv queue then and no event is logged.
Note that only tcp_inbound_ao_hash() uses a similar drop reason,
SKB_DROP_REASON_TCP_CLOSE, and this can be generalised later.
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Link: https://patch.msgid.link/20250116053441.5758-3-kuniyu@amazon.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
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The following patch adds a new drop reason starting with
the SOCKET_ prefix.
Let's gather the existing SOCKET_ reasons.
Note that the order is not part of uAPI.
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Link: https://patch.msgid.link/20250116053441.5758-2-kuniyu@amazon.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
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Prior patch in the series added TCP_RFC7323_PAWS_ACK drop reason.
This patch adds the corresponding SNMP counter, for folks
using nstat instead of tracing for TCP diagnostics.
nstat -az | grep PAWSOldAck
Suggested-by: Neal Cardwell <ncardwell@google.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Neal Cardwell <ncardwell@google.com>
Reviewed-by: Jason Xing <kerneljasonxing@gmail.com>
Tested-by: Neal Cardwell <ncardwell@google.com>
Reviewed-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Link: https://patch.msgid.link/20250113135558.3180360-4-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
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XPS can cause reorders because of the relaxed OOO
conditions for pure ACK packets.
For hosts not using RFS, what can happpen is that ACK
packets are sent on behalf of the cpu processing NIC
interrupts, selecting TX queue A for ACK packet P1.
Then a subsequent sendmsg() can run on another cpu.
TX queue selection uses the socket hash and can choose
another queue B for packets P2 (with payload).
If queue A is more congested than queue B,
the ACK packet P1 could be sent on the wire after
P2.
A linux receiver when processing P1 (after P2) currently increments
LINUX_MIB_PAWSESTABREJECTED (TcpExtPAWSEstab)
and use TCP_RFC7323_PAWS drop reason.
It might also send a DUPACK if not rate limited.
In order to better understand this pattern, this
patch adds a new drop_reason : TCP_RFC7323_PAWS_ACK.
For old ACKS like these, we no longer increment
LINUX_MIB_PAWSESTABREJECTED and no longer sends a DUPACK,
keeping credit for other more interesting DUPACK.
perf record -e skb:kfree_skb -a
perf script
...
swapper 0 [148] 27475.438637: skb:kfree_skb: ... location=tcp_validate_incoming+0x4f0 reason: TCP_RFC7323_PAWS_ACK
swapper 0 [208] 27475.438706: skb:kfree_skb: ... location=tcp_validate_incoming+0x4f0 reason: TCP_RFC7323_PAWS_ACK
swapper 0 [208] 27475.438908: skb:kfree_skb: ... location=tcp_validate_incoming+0x4f0 reason: TCP_RFC7323_PAWS_ACK
swapper 0 [148] 27475.439010: skb:kfree_skb: ... location=tcp_validate_incoming+0x4f0 reason: TCP_RFC7323_PAWS_ACK
swapper 0 [148] 27475.439214: skb:kfree_skb: ... location=tcp_validate_incoming+0x4f0 reason: TCP_RFC7323_PAWS_ACK
swapper 0 [208] 27475.439286: skb:kfree_skb: ... location=tcp_validate_incoming+0x4f0 reason: TCP_RFC7323_PAWS_ACK
...
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Neal Cardwell <ncardwell@google.com>
Reviewed-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Reviewed-by: Jason Xing <kerneljasonxing@gmail.com>
Link: https://patch.msgid.link/20250113135558.3180360-3-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
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The bridge input code may drop frames for various reasons and at various
points in the ingress handling logic. Currently kfree_skb() is used
everywhere, and therefore no drop reason is specified. Add drop reasons
to the most common drop points.
Drop reasons are not added exhaustively to the entire bridge code. The
intention is to incrementally add drop reasons to the rest of the bridge
code in follow up patches.
Signed-off-by: Radu Rendec <rrendec@redhat.com>
Reviewed-by: Ido Schimmel <idosch@nvidia.com>
Acked-by: Nikolay Aleksandrov <razor@blackwall.org>
Link: https://patch.msgid.link/20241219163606.717758-3-rrendec@redhat.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
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The SKB_DROP_REASON_VXLAN_NO_REMOTE skb drop reason was introduced in
the specific context of vxlan. As it turns out, there are similar cases
when a packet needs to be dropped in other parts of the network stack,
such as the bridge module.
Rename SKB_DROP_REASON_VXLAN_NO_REMOTE and give it a more generic name,
so that it can be used in other parts of the network stack. This is not
a functional change, and the numeric value of the drop reason even
remains unchanged.
Signed-off-by: Radu Rendec <rrendec@redhat.com>
Reviewed-by: Ido Schimmel <idosch@nvidia.com>
Acked-by: Nikolay Aleksandrov <razor@blackwall.org>
Link: https://patch.msgid.link/20241219163606.717758-2-rrendec@redhat.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
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Add three qdisc-specific drop reasons and use them in sch_cake:
1) SKB_DROP_REASON_QDISC_OVERLIMIT
Whenever the total queue limit for a qdisc instance is exceeded
and a packet is dropped to make room.
2) SKB_DROP_REASON_QDISC_CONGESTED
Whenever a packet is dropped by the qdisc AQM algorithm because
congestion is detected.
3) SKB_DROP_REASON_CAKE_FLOOD
Whenever a packet is dropped by the flood protection part of the
CAKE AQM algorithm (BLUE).
Also use the existing SKB_DROP_REASON_QUEUE_PURGE in cake_clear_tin().
Reasons show up as:
perf record -a -e skb:kfree_skb sleep 1; perf script
iperf3 665 [005] 848.656964: skb:kfree_skb: skbaddr=0xffff98168a333500 rx_sk=(nil) protocol=34525 location=__dev_queue_xmit+0x10f0 reason: QDISC_OVERLIMIT
swapper 0 [001] 909.166055: skb:kfree_skb: skbaddr=0xffff98168280cee0 rx_sk=(nil) protocol=34525 location=cake_dequeue+0x5ef reason: QDISC_CONGESTED
Reviewed-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Jamal Hadi Salim <jhs@mojatatu.com>
Acked-by: Dave Taht <dave.taht@gmail.com>
Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com>
Link: https://patch.msgid.link/20241211-cake-drop-reason-v2-1-920afadf4d1b@redhat.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
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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>
Reviewed-by: Victor Nogueira <victor@mojatatu.com>
Reviewed-by: Toke Høiland-Jørgensen <toke@redhat.com>
Acked-by: Jamal Hadi Salim <jhs@mojatatu.com>
Link: https://patch.msgid.link/20241204171950.89829-1-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
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In this commit, we make ip_mkroute_input() and __mkroute_input() return
drop reasons.
The drop reason "SKB_DROP_REASON_ARP_PVLAN_DISABLE" is introduced for
the case: the packet which is not IP is forwarded to the in_dev, and
the proxy_arp_pvlan is not enabled.
Signed-off-by: Menglong Dong <dongml2@chinatelecom.cn>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
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In this commit, we make ip_route_input_slow() return skb drop reasons,
and following new skb drop reasons are added:
SKB_DROP_REASON_IP_INVALID_DEST
The only caller of ip_route_input_slow() is ip_route_input_rcu(), and we
adjust it by making it return -EINVAL on error.
Signed-off-by: Menglong Dong <dongml2@chinatelecom.cn>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
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Make ip_mc_validate_source() return drop reason, and adjust the call of
it in ip_route_input_mc().
Another caller of it is ip_rcv_finish_core->udp_v4_early_demux, and the
errno is not checked in detail, so we don't do more adjustment for it.
The drop reason "SKB_DROP_REASON_IP_LOCALNET" is added in this commit.
Signed-off-by: Menglong Dong <dongml2@chinatelecom.cn>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
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In this commit, we make fib_validate_source() and __fib_validate_source()
return -reason instead of errno on error.
The return value of fib_validate_source can be -errno, 0, and 1. It's hard
to make fib_validate_source() return drop reasons directly.
The fib_validate_source() will return 1 if the scope of the source(revert)
route is HOST. And the __mkroute_input() will mark the skb with
IPSKB_DOREDIRECT in this case (combine with some other conditions). And
then, a REDIRECT ICMP will be sent in ip_forward() if this flag exists. We
can't pass this information to __mkroute_input if we make
fib_validate_source() return drop reasons.
Therefore, we introduce the wrapper fib_validate_source_reason() for
fib_validate_source(), which will return the drop reasons on error.
In the origin logic, LINUX_MIB_IPRPFILTER will be counted if
fib_validate_source() return -EXDEV. And now, we need to adjust it by
checking "reason == SKB_DROP_REASON_IP_RPFILTER". However, this will take
effect only after the patch "net: ip: make ip_route_input_noref() return
drop reasons", as we can't pass the drop reasons from
fib_validate_source() to ip_rcv_finish_core() in this patch.
Following new drop reasons are added in this patch:
SKB_DROP_REASON_IP_LOCAL_SOURCE
SKB_DROP_REASON_IP_INVALID_SOURCE
Signed-off-by: Menglong Dong <dongml2@chinatelecom.cn>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
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Replace kfree_skb() with kfree_skb_reason() in vxlan_xmit(). Following
new skb drop reasons are introduced for vxlan:
/* no remote found for xmit */
SKB_DROP_REASON_VXLAN_NO_REMOTE
/* packet without necessary metadata reached a device which is
* in "external" mode
*/
SKB_DROP_REASON_TUNNEL_TXINFO
Signed-off-by: Menglong Dong <dongml2@chinatelecom.cn>
Reviewed-by: Simon Horman <horms@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
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Change the return type of vxlan_set_mac() from bool to enum
skb_drop_reason. In this commit, the drop reason
"SKB_DROP_REASON_LOCAL_MAC" is introduced for the case that the source
mac of the packet is a local mac.
Signed-off-by: Menglong Dong <dongml2@chinatelecom.cn>
Reviewed-by: Simon Horman <horms@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
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Change the return type of vxlan_snoop() from bool to enum
skb_drop_reason. In this commit, two drop reasons are introduced:
SKB_DROP_REASON_MAC_INVALID_SOURCE
SKB_DROP_REASON_VXLAN_ENTRY_EXISTS
Signed-off-by: Menglong Dong <dongml2@chinatelecom.cn>
Reviewed-by: Simon Horman <horms@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
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Introduce skb drop reasons to the function vxlan_rcv(). Following new
drop reasons are added:
SKB_DROP_REASON_VXLAN_INVALID_HDR
SKB_DROP_REASON_VXLAN_VNI_NOT_FOUND
SKB_DROP_REASON_IP_TUNNEL_ECN
Signed-off-by: Menglong Dong <dongml2@chinatelecom.cn>
Reviewed-by: Simon Horman <horms@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
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Correct spelling in Networking headers.
As reported by codespell.
Signed-off-by: Simon Horman <horms@kernel.org>
Link: https://patch.msgid.link/20240822-net-spell-v1-12-3a98971ce2d2@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
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Soon later patches can use these relatively more accurate
reasons to recognise and find out the cause.
Signed-off-by: Jason Xing <kernelxing@tencent.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: David Ahern <dsahern@kernel.org>
Reviewed-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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Adding one drop reason to detect the condition of skb dropped
because of hook points in cookie check and extending NO_SOCKET
to consider another two cases can be used later.
Signed-off-by: Jason Xing <kernelxing@tencent.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: David Ahern <dsahern@kernel.org>
Reviewed-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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Continue expanding Daniel's patch by adding new skb drop reasons that
are idiosyncratic to TC.
More specifically:
- SKB_DROP_REASON_TC_COOKIE_ERROR: An error occurred whilst
processing a tc ext cookie.
- SKB_DROP_REASON_TC_CHAIN_NOTFOUND: tc chain lookup failed.
- SKB_DROP_REASON_TC_RECLASSIFY_LOOP: tc exceeded max reclassify loop
iterations
Signed-off-by: Victor Nogueira <victor@mojatatu.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
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Commit da37845fdce2 ("packet: uses kfree_skb() for errors.") switches
from consume_skb to kfree_skb to improve error handling. However, this
could bring a lot of noises when we monitor real packet drops in
kfree_skb[1], because in tpacket_rcv or packet_rcv only packet clones
can be freed, not actual packets.
Adding a generic drop reason to allow distinguish these "clone drops".
[1]: https://lore.kernel.org/netdev/CABWYdi00L+O30Q=Zah28QwZ_5RU-xcxLFUK2Zj08A8MrLk9jzg@mail.gmail.com/
Fixes: da37845fdce2 ("packet: uses kfree_skb() for errors.")
Suggested-by: Eric Dumazet <edumazet@google.com>
Suggested-by: Willem de Bruijn <willemdebruijn.kernel@gmail.com>
Signed-off-by: Yan Zhai <yan@cloudflare.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Willem de Bruijn <willemb@google.com>
Link: https://lore.kernel.org/r/ZW4piNbx3IenYnuw@debian.debian
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
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Introduce segment counters that are useful for troubleshooting/debugging
as well as for writing tests.
Now there are global snmp counters as well as per-socket and per-key.
Co-developed-by: Francesco Ruggeri <fruggeri@arista.com>
Signed-off-by: Francesco Ruggeri <fruggeri@arista.com>
Co-developed-by: Salam Noureddine <noureddine@arista.com>
Signed-off-by: Salam Noureddine <noureddine@arista.com>
Signed-off-by: Dmitry Safonov <dima@arista.com>
Acked-by: David Ahern <dsahern@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
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Now there is a common function to verify signature on TCP segments:
tcp_inbound_hash(). It has checks for all possible cross-interactions
with MD5 signs as well as with unsigned segments.
The rules from RFC5925 are:
(1) Any TCP segment can have at max only one signature.
(2) TCP connections can't switch between using TCP-MD5 and TCP-AO.
(3) TCP-AO connections can't stop using AO, as well as unsigned
connections can't suddenly start using AO.
Co-developed-by: Francesco Ruggeri <fruggeri@arista.com>
Signed-off-by: Francesco Ruggeri <fruggeri@arista.com>
Co-developed-by: Salam Noureddine <noureddine@arista.com>
Signed-off-by: Salam Noureddine <noureddine@arista.com>
Signed-off-by: Dmitry Safonov <dima@arista.com>
Acked-by: David Ahern <dsahern@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
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Introduce a helper that:
(1) shares the common code with TCP-MD5 header options parsing
(2) looks for hash signature only once for both TCP-MD5 and TCP-AO
(3) fails with -EEXIST if any TCP sign option is present twice, see
RFC5925 (2.2):
">> A single TCP segment MUST NOT have more than one TCP-AO in its
options sequence. When multiple TCP-AOs appear, TCP MUST discard
the segment."
Co-developed-by: Francesco Ruggeri <fruggeri@arista.com>
Signed-off-by: Francesco Ruggeri <fruggeri@arista.com>
Co-developed-by: Salam Noureddine <noureddine@arista.com>
Signed-off-by: Salam Noureddine <noureddine@arista.com>
Signed-off-by: Dmitry Safonov <dima@arista.com>
Acked-by: David Ahern <dsahern@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
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Add an initial user for the newly added tcf_set_drop_reason() helper to set the
drop reason for internal errors leading to TC_ACT_SHOT inside {__,}tcf_classify().
Right now this only adds a very basic SKB_DROP_REASON_TC_ERROR as a generic
fallback indicator to mark drop locations. Where needed, such locations can be
converted to more specific codes, for example, when hitting the reclassification
limit, etc.
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Cc: Jamal Hadi Salim <jhs@mojatatu.com>
Cc: Victor Nogueira <victor@mojatatu.com>
Link: https://lore.kernel.org/r/20231009092655.22025-2-daniel@iogearbox.net
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
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skb_queue_purge() and __skb_queue_purge() become wrappers
around the new generic functions.
New SKB_DROP_REASON_QUEUE_PURGE drop reason is added,
but users can start adding more specific reasons.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
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tcp_sequence() uses two conditions to decide to drop a packet,
and we currently report generic TCP_INVALID_SEQUENCE drop reason.
Duplicates are common, we need to distinguish them from
the other case.
I chose to not reuse TCP_OLD_DATA, and instead added
TCP_OLD_SEQUENCE drop reason.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Link: https://lore.kernel.org/r/20230719064754.2794106-1-edumazet@google.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
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Extend drop reasons to make them usable by subsystems
other than core by reserving the high 16 bits for a
new subsystem ID, of which 0 of course is used for the
existing reasons immediately.
To still be able to have string reasons, restructure
that code a bit to make the loopup under RCU, the only
user of this (right now) is drop_monitor.
Link: https://lore.kernel.org/netdev/00659771ed54353f92027702c5bbb84702da62ce.camel@sipsolutions.net
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
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This will, after the next patch, hold only the core
drop reasons and minimal infrastructure. Fix a small
kernel-doc issue while at it, to avoid the move
triggering a checker.
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
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