Solarflare Enhanced PTP Daemon

The sfptpd service synchronises local clocks together with multiple PTP and PPS sources in one integrated application with high quality timestamp filtering and supports LACP and active-backup bonds with and without VLANs. The default and Enterprise PTP profiles are supported.

Instantaneous and long term statistics for monitoring along with support for 'NetSync Monitor' and standard PTP event monitoring support compliance.

Integration is provided to work with NTP sources via ntpsec, ntpd and subject to limitations, chronyd. The daemon works on Linux systems for 3.0 kernels and later.

See the changelog for recent additions to sfptpd. The current stable branch is v3_7.

For a quick start (operating PTP on bond0, domain 100), see one line docker example.

Building and running from source

1. Change directory to the root of the sfptpd source repository or package
2. Type make all
3. The executable daemon is sfptpd in the build/ directory

The built sfptpd daemon does not require installation. However, it must normally be started as root.

Example installation recipies may be found in INSTALL.md and examples configuration files under config.

A simple back-to-back PTP example:

# On host A:
sudo build/sfptpd -i eth1 -f config/ptp_master_freerun.cfg

# On host B, first disabling ntpd and chronyd for simplicity:
for i in ntp{,d} chrony{,d}; do sudo service $i stop 2>/dev/null; done
sudo build/sfptpd -i eth1 -f config/ptp_slave.cfg

Supported releases

Supported releases of sfptpd are available from https://www.xilinx.com/download/drivers. These are supported by AMD for the Solarflare adapters and operating systems listed in the relevant release notes.

The user guide for supported releases is available at https://docs.xilinx.com/r/en-US/ug1602-ptp-user.

Community-supported usage

The sfptpd daemon provides a system-centric time sync solution that can be used with any network adapter and driver supporting standard Linux time APIs. This gives advantages over other software which lacks the same degree of support for link aggregation and which does not integrate remote and local synchronisation in one process.

Using non-Solarflare network adapters

Enable the use of non-Solarflare adapters with:

non_solarflare_nics on

By default non-Solarflare adapters are not synchronised to avoid potential limitations with their drivers:

Sfptpd is normally configured to synchronise all available NIC clocks automatically so that applications can obtain meaningful hardware timestamps on all interfaces.

In the case of Solarflare NICs, the sfc net driver presents the same "PTP Hardware Clock" (PHC) device (e.g. /dev/ptp0) for each of the physical network ports on a single adapter. Other NICs typically present an apparently independent PHC device for each network port.

However, these apparently independent PHC devices typically are not independent but represent the same underlying physical clock. This arrangement has one of two consequences:

1. When sfptpd tries to synchronise the same physical clock using apparently but not actually independent PHC devices, duplicate corrections occur. To mitigate this sfptpd has an option assume_one_phc_per_nic.
2. If all but one of the PHC devices is treated by the driver as read only and the instance made writable by the net driver is not the one on the lowest-numbered port, then with assume_one_phc_per_nic set to on, sfptpd will attempt to discipline the clock but there will be no effect. This situation can be mitigated by leaving assume_one_phc_per_nic off but that will result in wasteful clock comparisons for all the PHC devices that are effectively read only.

The current best recommendation to mitigate these limitations is to list explicitly the network ports of the NIC clocks to be disciplined with clock_list. Typically other software expects the clocks to be explicitly listed anyway.

Footnotes

SPDX-License-Identifier: BSD-3-Clause
SPDX-FileCopyrightText: (c) Copyright 2013-2024 Advanced Micro Devices, Inc.

This software is licensed as BSD-3-Clause AND BSD-2-Clause AND NTP AND ISC. See LICENSE file for details.