DUNE DAQ Core Software Meeting

Wednesday 20 Mar 2024, 09:00 → 10:05 US/Central

Kurt Biery (Fermilab), Roland Sipos (CERN)

Zoom:  https://fnal.zoom.us/j/91792149723

09:00 → 09:20 OKS status update

Speaker: Eric Flumerfelt (Fermilab)

OKS Update 20240320.pdf

OKS Update 20240320.pptx

09:20 → 09:35 DPDK/NICReceiver missed packets

Speaker: Roland Sipos (CERN)

20240320_145437.jpg

Screenshot from 2024-03-20 14-34-36.png

From SOFlow (  https://stackoverflow.com/questions/62387277/dpdk-19-11-ixgbe-pmd-got-imissed-when-up-to-8mppsdecreased-3mpps-any-one-have )

reasons for imissed in your applications could be the following reasons

1. CPU frequency is in power save and not performance (impact of not disabling C states in BIOS).
2. There is additional work or sleep added in RX thread loop will prevent rx_burst been invoked frequently
3. RSS is enabled, but traffic send to DPDK port is falling on 1 queue only. In case of too many RX queues like 16, this leads to increase delay to pick packet from the relevant queue.
4. iF RX thread is feeding worker cores based on flow id, there could be retries if RING full scenarios leading to loss of rx_burst.

If testpmd or example/skeleton or example/l2fwd is not having imissed. then here are my suggestions to debug your applciation.

1. try sending RX-TX from single-core
2. set power governed from powersave to performance.
3. ensure you are running the core threads on isolated cores.

09:35 → 09:50 AOB

Speakers: Kurt Biery (Fermilab), Roland Sipos (CERN)