A.o. Univ. Prof. Dr. Dipl.-Ing. eva Kühn
TU Wien

Roland Moser

Communication analysis of Distributed Data Acquisition Systems


Magister Thesis, TU-Vienna, 2007



The Compact Muon Solenid experiment for the Large Hadron Collider experiment at CERN uses a Distributed Data Acquisition System. This system samples, collects and processes sensor data. It consists of a cluster of computers with a switching fabric between them. For efficient data handling, segments of this switching fabric use Myrinet, a high throughput network technology [31] [33].


The programming environment for the CMS online system includes a framework for developing distributed systems called XDAQ. This framework decouples distributed applications from the underlying network technologies. For example the network technology can be changed from Ethernet to Myrinet without modifying the distributed application concerned [15] [13] [31].


The goal of this thesis is to measure the performance of the Myrinet network technology and understand the behavior of its hardware and software components. To improve the validity of the tests conducted for this thesis, the tests have been carried out in the CMS data acquisition test setup, which is a real-scale application. Results from analyzing different cluster configurations are presented as well as comparisons between tests performed using Myrinet and Ethernet.


During my Masters I have improved both my technical and social skills. I had to decide how to approach the integration of a new library into an existing system. I also had to decide, which Myrinet performance tests needed to be carried out. My work was conducted within the CMS DAQ project. This is a large scale multi-national project within which I have had to work collaboratively. Solving everything oneself is too time consuming and inefficient in such a large project.


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