[dpdk-dev] mlx5 & pdump: convert HW timestamps to nanoseconds

[PATRICK KEROULAS]

On Wed, Jun 3, 2020 at 3:48 AM Slava Ovsiienko <viacheslavo at mellanox.com> wrote:
>
> > From: PATRICK KEROULAS <patrick.keroulas at radio-canada.ca>
> > * rdma-code, libibverbs-dev: 28.0
> > * NIC Part Number:      MCX516A-CDA_Ax
> > * ConnectX-5 Ex EN
> > * FW: 16.25.1020
>
> It looks like outdated firmware, please:
> - update the firmware - at least 16.27.2008 is GA. I would recommend to install OFED - it updates the FW
> - make sure the UCTX_EN option in FW configuration is set to "true"

Hello Slava,

I managed to query device_frequency_khz by simply setting UCTX_EN=1,
convert the mbuf->timestamp to nsec and write a pcap. However, the
accuracy is quite disappointing, compared to libvma or even SW TS.

The freq value looks constant (=78125kHz). Correct me if I'm wrong, a
ptp client is supposed to continuously adjust some kind of VCO on the
NIC. And even setting a crazy value through /dev/ptp interface manually
doesn't affect device_frequency_khz. Please could you clarify?

This leads me back to mlx5dv_clock_info->nsec. If this is a valid method,
I think the only missing piece is to access it from the secondary process,
which implies to share ibv_context.

Best Regards,

PK