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Firefly is a shared-memory multiprocessor workstation that contains from one to seven MicroVAX 78032 processors, each with a floating point unit and a sixteen kilobyte cache. The caches are coherent, so that all processors see a consistent view of main memory. A system may contain from four to sixteen megabytes of storage. Input-output is done via a standard DEC QBus. Input-output devices are an Ethernet controller, fixed disks, and a monochrome 1024 x 768 display with keyboard and mouse. Optional hardware includes a high resolution color display and a controller for high capacity disks. Figure 1 is a system block diagram.The Firefly runs a software system that emulates the Ultrix system call interface. It also supports medium- and coarse-grained multiprocessing through multiple threads of control in a single address space. Communications are implemented uniformly through the use of remote procedure calls.This paper describes the goals, architecture, implementation and performance analysis of the Firefly. It then presents some measurements of hardware performance, and discusses the degree to which SRC has been successful in producing software to take advantage of multiprocessing.

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This paper quantitively evaluates the relevance of network jitter on player satisfaction and performance in multiplayer online games, particularly in comparison to overall network latency (or 'ping') times. We extend previously published work that showed Quake III players preferred servers less than 150-180ms away. Our modified, public Quake III server logged 20+ latency samples per second per client, from which we derived the jitter (instantaneous latency fluctuations) for each connected player. We found that using real-world traffic resulted in a highly correlated relationship between jitter and latency (jitter being generally one fifth, or less, of the path's latency), making it difficult to derive any independent relationship between jitter and player satisfaction. However, our results do demonstrate that absolute jitter over typical Internet paths is far less significant than the absolute latency for interactive games such as Quake III. This suggests Internet service providers (ISPs) should focus primarily on bringing latency within reasonable bounds.