> > I'm trying to build an accurate capture device based on Mellanox > > Connect-X5 with following requirements: > > - capture every incoming packets with hardware timestamps > > - output: pcap with timestamps in nanoseconds > > My problem is that the packets forwarded to `dpdk-pdump` carry raw > > timestamps from NIC clock. > > Please could you describe how you use dpdk-pdump? > Is it using the mlx5 PMD or pcap PMD?
We're actually using both: # Rx, receive from NIC CONFIG_RTE_LIBRTE_MLX5_PMD=y # Tx, output to pcap file CONFIG_RTE_LIBRTE_PMD_PCAP=y $ sudo ./build/app/testpmd -w 0000:01:00.0 -w 0000:01:00.1 -n4 -- --enable-rx-timestamp $ dpdk-pdump -- --pdump 'port=0,queue=*,rx-dev=capture.pcap' We've sent this placeholder with the intention to start the discussion. https://github.com/DPDK/dpdk/commit/bd371e1ba5bfc5b7092d712a01bbc28799fd58bc.patch https://github.com/DPDK/dpdk/commit/e6f5c731c4ab27ab80b229af98c9b3d257e13843.patch > > mlx5 part of libibverbs includes a ts-to-ns converter which takes the > > instantaneous clock info. It's unused in dpdk so far. I've tested it in the > > device/port init routine and the result looks reliable. Since this approach > > looks very simple, compared to the time sync mechanism, I'm trying to > > integrate. > > > > The conversion should occur in the primary process (testpmd) I suppose. > > 1) The needed clock info derives from ethernet device. Is it possible to > > access that struct from a rx callback? > > 2) how to attach the nanosecond to mbuf so that `pdump` catches it? > > (workaround: copy `mbuf->udata64` in forwarded packets.) > > 3) any other idea? > > The timestamp is carried in mbuf. > Then the conversion must be done by the ethdev caller (application or > any other upper layer). What if the converter function needs a clock_info? https://github.com/linux-rdma/rdma-core/blob/7af01c79e00555207dee6132d72e7bfc1bb5485e/providers/mlx5/mlx5dv.h#L1201 I'm affraid this info may change by the time the converter is called by upper layer. Thanks, PK
