2018-10-21 - 07:46
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OSADL Realtime QA Farm

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Real-time Ethernet (TSN) synchronization analysis

Wakeup latency of all systems - Real-time optimization - Peer-to-peer UDP duplex link - PTP/TSN - Powerlink - Ethercat - Network load - kvm - Sleep states

One of the Linux real-time test systems (rack #9, slot #3 at shadow position) serves as PTP grandmaster while receiving global time information via NTP in the same way as all other systems. This PTP server is connected to an industrial Cisco switch (type IE 3000-4TC) that is capable of handling PTP packets in level 2 and is configured to transparently forward them in an end-to-end mode. This switch is, in turn, connected to two real-time test systems (rack #b, slot #6 at primary and shadow position) that serve as PTP test clients and are equipped with continuous PTP jitter and system time jitter monitoring. They receive time information uniquely from the PTP link. Thus, the three peers, one PTP grandmaster and two PTP clients, share the same time information with the below depicted jitter and can be used to send SO_TXTIME packets across the peers with a predictable arrival time at the destination peer.

PTP grandmaster: Jitter analysis from system time to network adapter by week

Last update 14 minutes ago

Jitter analysis of time synchronization to the network adapter
Please note that the recorded values of this and of all below plots represent the maximum of subsequent 5-min intervals. Thus, from the given numerical values below the plot the only meaningful value is the one in the column labeled "Max:".

 

PTP client #1: Jitter analysis from network to network adapter and from network adapter to system by week

Last update 15 minutes ago

Jitter analysis of the network adapter
Jitter analysis from network to network adapter

Jitter analysis of the system
Jitter analysis from network adapter to system time

 

PTP client #2: Jitter analysis from network to network adapter and from network adapter to system by week

Last update 14 minutes ago

Jitter analysis of the network adapter
Jitter analysis from network to network adapter

Jitter analysis of the system
Jitter analysis from network adapter to system time