Accelerator Magnet Control from an SMP Workstation
Steve Herb, H.G. Wu
Deutsches Elektronen Synchrotron (DESY)
Standard commercial workstations and operating systems now support real time
scheduling on multiprocessor machines, which opens new possibilities for
structuring of control systems. We have built a prototype accelerator magnet
control system based on a Sparc 10 workstation with two processors running the
Solaris 2.4 operating system, which permits soft real time scheduling in a
symmetric multiprocessing environment. Fieldbus I/O is handled by a real time
task which monopolizes one processor and communicates via queues with VME
fieldbus drivers, leaving the other Sparc CPU free to handle a mix of real time
and time sharing tasks, including higher level controls functions and network
communications. Intertask communications use API level commands which access
queues and data structures built in shared memory with C++. Tests indicate
that the throughput is adequate for controlling the more than 1000 magnet power
supplies of the HERA electron and proton storage rings.