> > > > 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. > > Indeed, the clock in the device is not an atomic one :) > We need to adjust the time conversion continuously. > I am not an expert of time synchronization, so I add more people Cc > who could help for having a precise timestamp.
Thanks Thomas. Not sure this is a synchronization issue. We have dedicated processes (linuxptp) to keep both NIC and sys clocks in sync with an external clock. It is "just" a matter of unit conversion. If it has to be performed in dpdk-pdump, I would need some help to retrieve mlx5_clock_info from inside a secondary process. Looking at mlx5_read_clock(), this info is extracted from ibv_context which looks reachable in a primary process only (segfault, if I try in pdump).
