High performance message passing for the ATLAS DAQ/EF-1 project

Summary form only. A message passing library has been developed in the context of the ATLAS DAQ/EF-1 project. It is used for time critical applications within the front-end part of the DAQ system, mainly to exchange data control messages between I/O processors. Key objectives of the design were low message overheads, efficient use of the data transfer buses, provision of broadcast functionality and a hardware and operating system independent implementation of the application interface. The design and implementation of the message passing library are presented. As required by the project, the implementation is based on commercial components, namely VMEbus, PCI, the Lynx-OS real-time operating system and an additional inter-processor link, PVIC. The latter offers broadcast functionality identified as being important to the overall performance of the message passing. In addition, performance benchmarks for all implementing buses are presented for both simple test programs and the full DAQ applications.