User Manual

Driver FeaturesRev 2.0-3.0.0

Mellanox Technologies

4.6 Time-Stamping Service

Time stamping is the process of keeping track of the creation of a packet/ A time-stamping ser-

vice supports assertions of proof that a datum existed before a particular time. Incoming packets

are time-stamped before they are distributed on the PCI depending on the congestion in the PCI

buffers. Outgoing packets are time-stamped very close to placing them on the wire.

4.6.1 Enabling Time Stamping

Time-stamping is off by default and should be enabled before use.

 To enable time stamping for a socket:

• Call setsockopt() with SO_TIMESTAMPING and with the following flags:

 To enable time stamping for a net device:

Admin privileged user can enable/disable time stamping through calling ioctl(sock, SIOCSHWT-

STAMP, &ifreq) with following values:

Send side time sampling:

Time Stamping is currently at beta level.

Please be aware that everything listed here is subject to change.

Time Stamping is currently supported in ConnectX®-3/ConnectX®-3 Pro adapter

cards only.

SOF_TIMESTAMPING_TX_HARDWARE: try to obtain send time stamp in hardware

SOF_TIMESTAMPING_TX_SOFTWARE: if SOF_TIMESTAMPING_TX_HARDWARE is off or

fails, then do it in software

SOF_TIMESTAMPING_RX_HARDWARE: return the original, unmodified time stamp

as generated by the hardware

SOF_TIMESTAMPING_RX_SOFTWARE: if SOF_TIMESTAMPING_RX_HARDWARE is off or

fails, then do it in software

SOF_TIMESTAMPING_RAW_HARDWARE: return original raw hardware time stamp

SOF_TIMESTAMPING_SYS_HARDWARE: return hardware time stamp transformed to

the system time base

SOF_TIMESTAMPING_SOFTWARE: return system time stamp generated in

software

SOF_TIMESTAMPING_TX/RX determine how time stamps are generated.

SOF_TIMESTAMPING_RAW/SYS determine how they are reported