[PATCH iwl-next,v3 0/2] XDP Tx Hardware Timestamp for igc driver

From: Song Yoong Siang
Date: Sun Mar 03 2024 - 03:33:03 EST

Implemented XDP transmit hardware timestamp metadata for igc driver.

This patchset is tested with tools/testing/selftests/bpf/xdp_hw_metadata
on Intel ADL-S platform. Below are the test steps and results.

Test Step 1: Run xdp_hw_metadata app
sudo ./xdp_hw_metadata <iface> > /dev/shm/result.log

Test Step 2: Enable Tx hardware timestamp
sudo hwstamp_ctl -i <iface> -t 1 -r 1

Test Step 3: Run ptp4l and phc2sys for time synchronization

Test Step 4: Generate 1000 UDP packets with 1ms interval
sudo trafgen --dev <iface> '{eth(da=<mac addr>), udp(dp=9091)}' -t 1ms -n 1000

Result of last 3 packets:
poll: 1 (0) skip=50 fail=0 redir=998
xsk_ring_cons__peek: 1
0x55d7e76a02d0: rx_desc[997]->addr=96110 addr=96110 comp_addr=96110 EoP
rx_hash: 0x11A51182 with RSS type:0x1
HW RX-time: 1677795020447895823 (sec:1677795020.4479) delta to User RX-time sec:0.0000 (16.309 usec)
XDP RX-time: 1677795020447906552 (sec:1677795020.4479) delta to User RX-time sec:0.0000 (5.580 usec)
No rx_vlan_tci or rx_vlan_proto, err=-95
0x55d7e76a02d0: ping-pong with csum=ab19 (want 315b) csum_start=34 csum_offset=6
0x55d7e76a02d0: complete tx idx=997 addr=65010
HW TX-complete-time: 1677795020447961519 (sec:1677795020.4480) delta to User TX-complete-time sec:0.0001 (79.979 usec)
XDP RX-time: 1677795020447906552 (sec:1677795020.4479) delta to User TX-complete-time sec:0.0001 (134.946 usec)
HW RX-time: 1677795020447895823 (sec:1677795020.4479) delta to HW TX-complete-time sec:0.0001 (65.696 usec)
0x55d7e76a02d0: complete rx idx=1125 addr=96110

poll: 1 (0) skip=50 fail=0 redir=999
xsk_ring_cons__peek: 1
0x55d7e76a02d0: rx_desc[998]->addr=98110 addr=98110 comp_addr=98110 EoP
rx_hash: 0x11A51182 with RSS type:0x1
HW RX-time: 1677795020448904440 (sec:1677795020.4489) delta to User RX-time sec:0.0000 (15.920 usec)
XDP RX-time: 1677795020448915139 (sec:1677795020.4489) delta to User RX-time sec:0.0000 (5.221 usec)
No rx_vlan_tci or rx_vlan_proto, err=-95
0x55d7e76a02d0: ping-pong with csum=ab19 (want 315b) csum_start=34 csum_offset=6
0x55d7e76a02d0: complete tx idx=998 addr=66010
HW TX-complete-time: 1677795020448969442 (sec:1677795020.4490) delta to User TX-complete-time sec:0.0001 (80.163 usec)
XDP RX-time: 1677795020448915139 (sec:1677795020.4489) delta to User TX-complete-time sec:0.0001 (134.466 usec)
HW RX-time: 1677795020448904440 (sec:1677795020.4489) delta to HW TX-complete-time sec:0.0001 (65.002 usec)
0x55d7e76a02d0: complete rx idx=1126 addr=98110

poll: 1 (0) skip=50 fail=0 redir=1000
xsk_ring_cons__peek: 1
0x55d7e76a02d0: rx_desc[999]->addr=99110 addr=99110 comp_addr=99110 EoP
rx_hash: 0x11A51182 with RSS type:0x1
HW RX-time: 1677795020449912415 (sec:1677795020.4499) delta to User RX-time sec:0.0000 (16.441 usec)
XDP RX-time: 1677795020449923362 (sec:1677795020.4499) delta to User RX-time sec:0.0000 (5.494 usec)
No rx_vlan_tci or rx_vlan_proto, err=-95
0x55d7e76a02d0: ping-pong with csum=ab19 (want 315b) csum_start=34 csum_offset=6
0x55d7e76a02d0: complete tx idx=999 addr=67010
HW TX-complete-time: 1677795020449977468 (sec:1677795020.4500) delta to User TX-complete-time sec:0.0001 (81.036 usec)
XDP RX-time: 1677795020449923362 (sec:1677795020.4499) delta to User TX-complete-time sec:0.0001 (135.142 usec)
HW RX-time: 1677795020449912415 (sec:1677795020.4499) delta to HW TX-complete-time sec:0.0001 (65.053 usec)
0x55d7e76a02d0: complete rx idx=1127 addr=99110

Besides, this patchset is tested with iperf3 to check the impact of holding tx completion.
Based on results below, the impact is not observable.

Result of iperf3 without trafgen command in step 4:
[ ID] Interval Transfer Bitrate Retr
[ 5] 0.00-100.00 sec 27.4 GBytes 2.35 Gbits/sec 0 sender
[ 5] 0.00-100.04 sec 27.4 GBytes 2.35 Gbits/sec receiver

Result of iperf3 running parallel with trafgen command in step 4:
[ ID] Interval Transfer Bitrate Retr
[ 5] 0.00-100.00 sec 27.4 GBytes 2.35 Gbits/sec 0 sender
[ 5] 0.00-100.04 sec 27.4 GBytes 2.35 Gbits/sec receiver

V1: https://patchwork.kernel.org/project/netdevbpf/patch/20231215162158.951925-1-yoong.siang.song@xxxxxxxxx/
V2: https://patchwork.kernel.org/project/netdevbpf/cover/20240301162348.898619-1-yoong.siang.song@xxxxxxxxx/

changelog:
V1 -> V2
- In struct igc_tx_timestamp_request, keep a pointer to igc_tx_buffer,
instead of pointing xsk_pending_ts (Vinicius).
- In struct igc_tx_timestamp_request, introduce buffer_type to indicate
whether skb or igc_tx_buffer pointer should be use (Vinicius).
- In struct igc_metadata_request, remove igc_adapter pointer (Vinicius).
- When request tx hwts, copy the value of cmd_type, instead of using
pointer (Vinicius).
- For boolean variable, use true and false, instead of 1 and 0 (Vinicius).
- In igc_xsk_request_timestamp(), make an early return if none of the 4 ts
registers is available (Vinicius).
- Create helper functions to clear tx buffer and skb for tstamp (John).
- Perform throughput test with mix traffic (Vinicius & John).
V2 -> V3
- Improve tstamp reg searching loop for better readability.
- In igc_ptp_free_tx_buffer(), add comment to inform user that
tstamp->xsk_tx_buffer and tstamp->skb are in union.

Song Yoong Siang (2):
selftests/bpf: xdp_hw_metadata reduce sleep interval
igc: Add Tx hardware timestamp request for AF_XDP zero-copy packet

drivers/net/ethernet/intel/igc/igc.h | 71 ++++++-----
drivers/net/ethernet/intel/igc/igc_main.c | 113 +++++++++++++++++-
drivers/net/ethernet/intel/igc/igc_ptp.c | 45 +++++--
tools/testing/selftests/bpf/xdp_hw_metadata.c | 2 +-
4 files changed, 190 insertions(+), 41 deletions(-)

--
2.34.1