On 11/06/2025 12:08, chia-yu.chang@nokia-bell-labs.com wrote:
From: Chia-Yu Chang chia-yu.chang@nokia-bell-labs.com
Hello,
Please find the DualPI2 patch v17.
This patch serise adds DualPI Improved with a Square (DualPI2) with following features:
- Supports congestion controls that comply with the Prague requirements in RFC9331 (e.g. TCP-Prague)
- Coupled dual-queue that separates the L4S traffic in a low latency queue (L-queue), without harming remaining traffic that is scheduled in classic queue (C-queue) due to congestion-coupling using PI2 as defined in RFC9332
- Configurable overload strategies
- Use of sojourn time to reliably estimate queue delay
- Supports ECN L4S-identifier (IP.ECN==0b*1) to classify traffic into respective queues
For more details of DualPI2, please refer IETF RFC9332 (https://datatracker.ietf.org/doc/html/rfc9332).
Best regards, Chia-Yu
v17 (25-May-2025, Resent at 11-Jun-2025)
- Replace 0xffffffff with U32_MAX (Paolo Abeni pabeni@redhat.com)
- Use helper function qdisc_dequeue_internal() and add new helper function skb_apply_step() (Paolo Abeni pabeni@redhat.com)
- Add s64 casting when calculating the delta of the PI controller (Paolo Abeni pabeni@redhat.com)
- Change the drop reason into SKB_DROP_REASON_QDISC_CONGESTED for drop_early (Paolo Abeni pabeni@redhat.com)
- Modify the condition to remove the original skb when enqueuing multiple GSO segments (Paolo Abeni pabeni@redhat.com)
- Add READ_ONCE() in dualpi2_dump_stat() (Paolo Abeni pabeni@redhat.com)
- Add comments, brackets, and brackets for readability (Paolo Abeni pabeni@redhat.com)
v16 (16-MAy-2025)
- Add qdisc_lock() to dualpi2_timer() in dualpi2_timer (Paolo Abeni pabeni@redhat.com)
- Introduce convert_ns_to_usec() to convert usec to nsec without overflow in #1 (Paolo Abeni pabeni@redhat.com)
- Update convert_us_tonsec() to convert nsec to usec without overflow in #2 (Paolo Abeni pabeni@redhat.com)
- Add more descriptions with respect to DualPI2 in the cover ltter and add changelog in each patch (Paolo Abeni pabeni@redhat.com)
v15 (09-May-2025)
- Add enum of TCA_DUALPI2_ECN_MASK_CLA_ECT to remove potential leakeage in #1 (Simon Horman horms@kernel.org)
- Fix one typo in comment of #2
- Update tc.yaml in #5 to aligh with the updated enum of pkt_sched.h
v14 (05-May-2025)
- Modify tc.yaml: (1) Replace flags with enum and remove enum-as-flags, (2) Remove credit-queue in xstats, and (3) Change attribute types (Donald Hunter <donald.hun
- Add enum and fix the ordering of variables in pkt_sched.h to align with the modified tc.yaml (Donald Hunter donald.hunter@gmail.com)
- Add validators for DROP_OVERLOAD, DROP_EARLY, ECN_MASK, and SPLIT_GSO in sch_dualpi2.c (Donald Hunter donald.hunter@gmail.com)
- Update dualpi2.json to align with the updated variable order in pkt_sched.h
- Reorder patches (Donald Hunter donald.hunter@gmail.com)
v13 (26-Apr-2025)
- Use dashes in member names to follow YNL conventions in tc.yaml (Donald Hunter donald.hunter@gmail.com)
- Define enumerations separately for flags of drop-early, drop-overload, ecn-mask, credit-queue in tc.yaml (Donald Hunter donald.hunter@gmail.com)
- Change the types of split-gso and step-packets into flag in tc.yaml (Donald Hunter donald.hunter@gmail.com)
- Revert to u32/u8 types for tc-dualpi2-xstats members in tc.yaml (Donald Hunter donald.hunter@gmail.com)
- Add new test cases in tc-tests/qdiscs/dualpi2.json to cover all dualpi2 parameters (Donald Hunter donald.hunter@gmail.com)
- Change the type of TCA_DUALPI2_STEP_PACKETS into NLA_FLAG (Donald Hunter donald.hunter@gmail.com)
v12 (22-Apr-2025)
- Remove anonymous struct in sch_dualpi2.c (Paolo Abeni pabeni@redhat.com)
- Replace u32/u8 with uint and s32 with int in tc spec document (Paolo Abeni pabeni@redhat.com)
- Introduce get_memory_limit function to handle potential overflow when multipling limit with MTU (Paolo Abeni pabeni@redhat.com)
- Double the packet length to further include packet overhead in memory_limit (Paolo Abeni pabeni@redhat.com)
- Remove the check of qdisc_qlen(sch) when calling qdisc_tree_reduce_backlog (Paolo Abeni pabeni@redhat.com)
v11 (15-Apr-2025)
- Replace hstimer_init with hstimer_setup in sch_dualpi2.c
v10 (25-Mar-2025)
- Remove leftover include in include/linux/netdevice.h and anonymous struct in sch_dualpi2.c (Paolo Abeni pabeni@redhat.com)
- Use kfree_skb_reason() and add SKB_DROP_REASON_DUALPI2_STEP_DROP drop reason (Paolo Abeni pabeni@redhat.com)
- Split sch_dualpi2.c into 3 patches (and overall 5 patches): Struct definition & parsing, Dump stats & configuration, Enqueue/Dequeue (Paolo Abeni pabeni@redhat.com)
v9 (16-Mar-2025)
Fix mem_usage error in previous version
Add min_qlen_step to the dualpi2 attribute as the minimum queue length in number of packets in the L-queue to start step threshold marking. In previous versions, this value was fixed to 2, so the step threshold was applied to mark packets in the L queue only when the queue length of the L queue was greater than or equal to 2 packets. This will cause larger queuing delays for L4S traffic at low rates (<20Mbps). So we parameterize it and change the default value to 0. Comparison of tcp_1down run 'HTB 20Mbit + DUALPI2 + 10ms base delay' Old versions: avg median # data pts Ping (ms) ICMP : 11.55 11.70 ms 350 TCP upload avg : 18.96 N/A Mbits/s 350 TCP upload sum : 18.96 N/A Mbits/s 350
New version (v9): avg median # data pts Ping (ms) ICMP : 10.81 10.70 ms 350 TCP upload avg : 18.91 N/A Mbits/s 350 TCP upload sum : 18.91 N/A Mbits/s 350
Comparison of tcp_1down run 'HTB 10Mbit + DUALPI2 + 10ms base delay' Old versions: avg median # data pts Ping (ms) ICMP : 12.61 12.80 ms 350 TCP upload avg : 9.48 N/A Mbits/s 350 TCP upload sum : 9.48 N/A Mbits/s 350
New version (v9): avg median # data pts Ping (ms) ICMP : 11.06 10.80 ms 350 TCP upload avg : 9.43 N/A Mbits/s 350 TCP upload sum : 9.43 N/A Mbits/s 350
Comparison of tcp_1down run 'HTB 10Mbit + DUALPI2 + 10ms base delay' Old versions: avg median # data pts Ping (ms) ICMP : 40.86 37.45 ms 350 TCP upload avg : 0.88 N/A Mbits/s 350 TCP upload sum : 0.88 N/A Mbits/s 350 TCP upload::1 : 0.88 0.97 Mbits/s 350
New version (v9): avg median # data pts Ping (ms) ICMP : 11.07 10.40 ms 350 TCP upload avg : 0.55 N/A Mbits/s 350 TCP upload sum : 0.55 N/A Mbits/s 350 TCP upload::1 : 0.55 0.59 Mbits/s 350
v8 (11-Mar-2025)
- Fix warning messages in v7
v7 (07-Mar-2025)
- Separate into 3 patches to avoid mixing changes of documentation, selftest, and code. (Cong Wang xiyou.wangcong@gmail.com)
v6 (04-Mar-2025)
- Add modprobe for dulapi2 in tc-testing script tc-testing/tdc.sh (Jakub Kicinski kuba@kernel.org)
- Update test cases in dualpi2.json
- Update commit message
v5 (22-Feb-2025)
A comparison was done between MQ + DUALPI2, MQ + FQ_PIE, MQ + FQ_CODEL: Unshaped 1gigE with 4 download streams test:
Summary of tcp_4down run 'MQ + FQ_CODEL': avg median # data pts Ping (ms) ICMP : 1.19 1.34 ms 349 TCP download avg : 235.42 N/A Mbits/s 349 TCP download sum : 941.68 N/A Mbits/s 349 TCP download::1 : 235.19 235.39 Mbits/s 349 TCP download::2 : 235.03 235.35 Mbits/s 349 TCP download::3 : 236.89 235.44 Mbits/s 349 TCP download::4 : 234.57 235.19 Mbits/s 349
Summary of tcp_4down run 'MQ + FQ_PIE' avg median # data pts Ping (ms) ICMP : 1.21 1.37 ms 350 TCP download avg : 235.42 N/A Mbits/s 350 TCP download sum : 941.61 N/A Mbits/s 350 TCP download::1 : 232.54 233.13 Mbits/s 350 TCP download::2 : 232.52 232.80 Mbits/s 350 TCP download::3 : 233.14 233.78 Mbits/s 350 TCP download::4 : 243.41 241.48 Mbits/s 350
Summary of tcp_4down run 'MQ + DUALPI2' avg median # data pts Ping (ms) ICMP : 1.19 1.34 ms 349 TCP download avg : 235.42 N/A Mbits/s 349 TCP download sum : 941.68 N/A Mbits/s 349 TCP download::1 : 235.19 235.39 Mbits/s 349 TCP download::2 : 235.03 235.35 Mbits/s 349 TCP download::3 : 236.89 235.44 Mbits/s 349 TCP download::4 : 234.57 235.19 Mbits/s 349
Unshaped 1gigE with 128 download streams test:
Summary of tcp_128down run 'MQ + FQ_CODEL': avg median # data pts Ping (ms) ICMP : 1.88 1.86 ms 350 TCP download avg : 7.39 N/A Mbits/s 350 TCP download sum : 946.47 N/A Mbits/s 350
Summary of tcp_128down run 'MQ + FQ_PIE': avg median # data pts Ping (ms) ICMP : 1.88 1.86 ms 350 TCP download avg : 7.39 N/A Mbits/s 350 TCP download sum : 946.47 N/A Mbits/s 350
Summary of tcp_128down run 'MQ + DUALPI2': avg median # data pts Ping (ms) ICMP : 1.88 1.86 ms 350 TCP download avg : 7.39 N/A Mbits/s 350 TCP download sum : 946.47 N/A Mbits/s 350
Unshaped 10gigE with 4 download streams test:
Summary of tcp_4down run 'MQ + FQ_CODEL': avg median # data pts Ping (ms) ICMP : 0.22 0.23 ms 350 TCP download avg : 2354.08 N/A Mbits/s 350 TCP download sum : 9416.31 N/A Mbits/s 350 TCP download::1 : 2353.65 2352.81 Mbits/s 350 TCP download::2 : 2354.54 2354.21 Mbits/s 350 TCP download::3 : 2353.56 2353.78 Mbits/s 350 TCP download::4 : 2354.56 2354.45 Mbits/s 350
Summary of tcp_4down run 'MQ + FQ_PIE': avg median # data pts Ping (ms) ICMP : 0.20 0.19 ms 350 TCP download avg : 2354.76 N/A Mbits/s 350 TCP download sum : 9419.04 N/A Mbits/s 350 TCP download::1 : 2354.77 2353.89 Mbits/s 350 TCP download::2 : 2353.41 2354.29 Mbits/s 350 TCP download::3 : 2356.18 2354.19 Mbits/s 350 TCP download::4 : 2354.68 2353.15 Mbits/s 350
Summary of tcp_4down run 'MQ + DUALPI2': avg median # data pts Ping (ms) ICMP : 0.24 0.24 ms 350 TCP download avg : 2354.11 N/A Mbits/s 350 TCP download sum : 9416.43 N/A Mbits/s 350 TCP download::1 : 2354.75 2353.93 Mbits/s 350 TCP download::2 : 2353.15 2353.75 Mbits/s 350 TCP download::3 : 2353.49 2353.72 Mbits/s 350 TCP download::4 : 2355.04 2353.73 Mbits/s 350
Unshaped 10gigE with 128 download streams test:
Summary of tcp_128down run 'MQ + FQ_CODEL': avg median # data pts Ping (ms) ICMP : 7.57 8.69 ms 350 TCP download avg : 73.97 N/A Mbits/s 350 TCP download sum : 9467.82 N/A Mbits/s 350
Summary of tcp_128down run 'MQ + FQ_PIE': avg median # data pts Ping (ms) ICMP : 7.82 8.91 ms 350 TCP download avg : 73.97 N/A Mbits/s 350 TCP download sum : 9468.42 N/A Mbits/s 350
Summary of tcp_128down run 'MQ + DUALPI2': avg median # data pts Ping (ms) ICMP : 6.87 7.93 ms 350 TCP download avg : 73.95 N/A Mbits/s 350 TCP download sum : 9465.87 N/A Mbits/s 350
From the results shown above, we see small differences between combinations.
Update commit message to include results of no_split_gso and split_gso (Dave Taht dave.taht@gmail.com and Paolo Abeni pabeni@redhat.com)
Add memlimit in the dualpi2 attribute, and add memory_used, max_memory_used, memory_limit in dualpi2 stats (Dave Taht dave.taht@gmail.com)
Update note in sch_dualpi2.c related to BBRv3 status (Dave Taht dave.taht@gmail.com)
Update license identifier (Dave Taht dave.taht@gmail.com)
Add selftest in tools/testing/selftests/tc-testing (Cong Wang xiyou.wangcong@gmail.com)
Use netlink policies for parameter checks (Jamal Hadi Salim jhs@mojatatu.com)
Modify texts & fix typos in Documentation/netlink/specs/tc.yaml (Dave Taht dave.taht@gmail.com)
Add descriptions of packet counter statistics and the reset function of sch_dualpi2.c
Fix step_thresh in packets
Update code comments in sch_dualpi2.c
v4 (22-Oct-2024)
- Update statement in Kconfig for DualPI2 (Stephen Hemminger stephen@networkplumber.org)
- Put a blank line after #define in sch_dualpi2.c (Stephen Hemminger stephen@networkplumber.org)
- Fix line length warning.
v3 (19-Oct-2024)
- Fix compilaiton error
- Update Documentation/netlink/specs/tc.yaml (Jakub Kicinski kuba@kernel.org)
v2 (18-Oct-2024)
- Add Documentation/netlink/specs/tc.yaml (Jakub Kicinski kuba@kernel.org)
- Use dualpi2 instead of skb prefix (Jamal Hadi Salim jhs@mojatatu.com)
- Replace nla_parse_nested_deprecated with nla_parse_nested (Jamal Hadi Salim jhs@mojatatu.com)
- Fix line length warning
Chia-Yu Chang (4): sched: Struct definition and parsing of dualpi2 qdisc sched: Dump configuration and statistics of dualpi2 qdisc selftests/tc-testing: Add selftests for qdisc DualPI2 Documentation: netlink: specs: tc: Add DualPI2 specification
Koen De Schepper (1): sched: Add enqueue/dequeue of dualpi2 qdisc
Documentation/netlink/specs/tc.yaml | 156 +++ include/net/dropreason-core.h | 6 + include/uapi/linux/pkt_sched.h | 68 + net/sched/Kconfig | 12 + net/sched/Makefile | 1 + net/sched/sch_dualpi2.c | 1146 +++++++++++++++++ tools/testing/selftests/tc-testing/config | 1 + .../tc-testing/tc-tests/qdiscs/dualpi2.json | 254 ++++ tools/testing/selftests/tc-testing/tdc.sh | 1 + 9 files changed, 1645 insertions(+) create mode 100644 net/sched/sch_dualpi2.c create mode 100644 tools/testing/selftests/tc-testing/tc-tests/qdiscs/dualpi2.json
Build broke:
net/sched/sch_dualpi2.c: In function ‘dualpi2_timer’: net/sched/sch_dualpi2.c:711:40: error: implicit declaration of function ‘from_timer’; did you mean ‘mod_timer’? [-Werror=implicit-function-declaration] 711 | struct dualpi2_sched_data *q = from_timer(q, timer, pi2_timer); | ^~~~~~~~~~ | mod_timer net/sched/sch_dualpi2.c:711:61: error: ‘pi2_timer’ undeclared (first use in this function); did you mean ‘bpf_timer’? 711 | struct dualpi2_sched_data *q = from_timer(q, timer, pi2_timer); | ^~~~~~~~~ | bpf_timer