Experimental Results

 

Figure: With out-of-order transfers, download requests take almost constant time to complete as the load increases. When file data transfers are served sequentially, however, the download duration increases significantly as a function of the system load. We consider the case where all clients have the same network link capacity (a-c), and when clients of different link capacities are served by a single server (d-f). It is our objective to minimize the download time of the file transfers.

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We compare the performance of the Circus prototype with an unmodified FreeBSD 4.5 ftpd implementation. In our experimentation, we investigate alternative client features, network conditions, file characteristics, and server configuration parameters. We find Circus to significantly improve the server throughput, and dramatically reduce the file download time.