• Using the native compiler on a target example:
$ gcc <filename>.c -o <filename>.out -lrt –Wall
Scheduling policies have two classes:
Completely Fair Scheduling (CFS)
• SCHED_NORMAL
• SCHED_BATCH
• SCHED_IDLE
RT policies:
• SCHED_FIFO
• SCHED_RR
• SCHED_DEADLINE
4.5 IEEE 1588
This section provides an introduction to the IEEE 1588 features of Open IL. It includes a description of the Precision Time Protocol
(PTP) device types, Linux PTP stack, quick start guide for implementing PTP based on the IEEE standard 1588 for Linux, known
issues and limitations, and long term test results.
4.5.1 Introduction
IEEE Std 1588-2008 (IEEE Standard for a Precision Clock Synchronization Protocol for Networked Measurement and Control
Systems) defines a protocol enabling precise synchronization of clocks in measurement and control systems implemented with
technologies such as network communication, local computing, and distributed objects.
The 1588 timer module on NXP QorIQ platform provides hardware assist for 1588 compliant time stamping. Together with a
software PTP (Precision Time Protocol) stack, it implements precision clock synchronization defined by this standard. Many open
source PTP stacks are available with a little transplant effort, such as linuxptp, which are used for this release demo.
4.5.2 PTP device types
There are five basic types of PTP devices, as follows:
• Ordinary clock: A clock that has a single Precision Time Protocol (PTP) port in a domain and maintains the timescale used
in the domain. It may serve as a source of time (be a master clock) or may synchronize to another clock (be a slave clock).
• Boundary clock: A clock that has multiple Precision Time Protocol (PTP) ports in a domain and maintains the timescale used
in the domain. It may serve as a source of time (be a master clock) or may synchronize to another clock (be a slave clock).
• End-to-end transparent clock: A transparent clock that supports the use of the end-to-end delay measurement mechanism
between slave clocks and the master clock.
• Peer-to-peer transparent clock: A transparent clock that, in addition to providing Precision Time Protocol (PTP) event transit
time information, also provides corrections for the propagation delay of the link connected to the port receiving the PTP event
message. In the presence of peer-to-peer transparent clocks, delay measurements between slave clocks and the master
clock are performed using the peer-to-peer delay measurement mechanism.
• Management node: A device that configures and monitors clocks.
Transparent clock, is a device that measures the time taken for a Precision Time Protocol (PTP) event message
to transit the device and provides this information to clocks receiving this PTP event message.
NOTE
NXP Semiconductors
Industrial features
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