Hi,
I am looking into getting the hardware
timestamp of when a packet is received by the NIC inside of my
DPDK program. In a regular program I can get the timestamp the
packet is received by the NIC and the kernel using SO_TIMESTAMPING [0]. Is there a way to get this
timestamp in dpdk?
What I found when looking for this, it looks like `mbuf->timestamp` was deprecated [1] and was replaced in this [2] example by `rte_mbuf_timestamp_t` (in hwts_field). When looking at the values I get from `hwts_field` it cycles around 50244192 though, going up _and_ down?
Looking at the output I am unsure what is
actually being measured by the rxtx_callback example. With a
hardware freq. of 156024300 and about 40 cycles the latency
is about 262ns. But what is this latency? From the time the
packet is received by the NIC to the first time dpdk
interacts with it? Or when I get the packet in my dpdk
program?
Thanks
Arne
[0]
https://docs.kernel.org/networking/timestamping.html
[1] https://github.com/DPDK/dpdk/commit/c7e857e16fda217cb9fd3644b66abe19daa3afb3
[1]
https://github.com/DPDK/dpdk/blob/main/examples/rxtx_callbacks/main.c#L101