The data acquisition system for the CMS experiment at the Large Hadron Collider (LHC) will require a large and high performance event building network. Several switch technologies are currently being ...evaluated in order to compare different architectures for the event builder. One candidate is Myrinet. This paper describes the demonstrator which has been setup to study a small-scale (16×16) event builder based on PCs running Linux connected to Myrinet and Ethernet switches.
A detailed study of the Myrinet switch performance has been performed for various traffic conditions, including the behaviour of composite switches. Results from event building studies are presented, including measurements on throughput, overhead and scaling. Traffic shaping techniques have been implemented and the effect on the event building performance has been investigated. The paper reports on performances and maximum event rate obtainable using custom software, not described, for the Myrinet control program and the low-level communication layer, implemented in a driver for Linux. A high performance sender is emulated by creating a dummy buffer that remains resident in the network interface and moving from the host only the first 64 bytes used by the event building protocol. An approximate scaling in
N is presented assuming a balanced system where each source sends on average data to all destinations with the same rate.
The data acquisition system for the CMS experiment at the Large Hadron Collider (LHC) will require a large and high performance event building network. Several switch technologies are currently being ...evaluated in order to compare different architectures for the event builder. One candidate is Myrinet. This paper describes the demonstrator which has been set up to study a small-scale (8/spl times/8) event builder based on a Myrinet switch. Measurements are presented on throughput, overhead and scaling for various traffic conditions. Results are shown on event building with a push architecture.
Traditional systems dominated by performance constraints tend to neglect other qualities such as maintainability and configurability. Object-Orientation allows one to encapsulate the technology ...differences in communication sub-systems and to provide a uniform view of data transport layer to the systems engineer. We applied this paradigm to the design and implementation of intelligent data servers in the Compact Muon Solenoid (CMS) data acquisition system at CERN to easily exploiting the physical communication resources of the available equipment. CMS is a high-energy physics experiment under study that incorporates a highly distributed data acquisition system. This paper outlines the architecture of one part, the so called Readout Unit, and shows how we can exploit the object advantage for systems with specific data rate requirements. A C++ streams communication layer with zero copying functionality has been established for UDP, TCP, DLPI and specific Myrinet and VME bus communication on the VxWorks real-time operating system. This software provides performance close to the hardware channel and hides communication details from the application programmers.
Argon purification in the liquid phase
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
09/1993
Journal Article
Mainstream computing equipment and the advent of affordable multi-Gigabit communication technology permit us to address grand-challenge data acquisition and processing problems with clusters of ...inexpensive computers. Such networks typically incorporate heterogeneous equipment, real-time partitions and even custom devices. Vital overall system requirements are high efficiency and flexibility. In preceding projects we experienced the difficulties to cover both requirements at once. Intelligent I/O (I/sub 2/O) is an industry specification that defines a uniform messaging format and execution environment for hardwareand operating system independent device drivers in computing systems with processor based communication equipment. Mapping this concept to a distributed computing environment and encapsulating the details of the specification into an application-programming framework allow us to provide architectural support for (i) efficient and (ii) extensible cluster operation. This paper portrays our view of applying I/sub 2/O to high-performance clusters. We demonstrate the feasibility of this approach by giving efficiency measurements of our XDAQ software framework for distributed data acquisition systems.
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