X Window System Network Performance Keith Packard Cambridge Research Laboratory, HP Labs, HP
[email protected] James Gettys Cambridge Research Laboratory, HP Labs, HP
[email protected] Abstract havior (or on a local machine, context switches between the application and the X server). Performance was an important issue in the develop- One of the authors used the network visualization tool ment of X from the initial protocol design and contin- when analyzing the design of HTTP/1.1 [NGBS 97]. ues to be important in modern application and extension The methodology and tools used in that analysis in- development. That X is network transparent allows us volved passive packet level monitoring of traffic which to analyze the behavior of X from a perspective seldom allowed precise real-world measurements and compar- possible in most systems. We passively monitor network isons. The work described in this paper combines this packet flow to measure X application and server perfor- passive packet capture methodology with additional X mance. The network simulation environment, the data protocol specific analysis and visualization. Our experi- capture tool and data analysis tools will be presented. ence with this combination of the general technique with Data from this analysis are used to show the performance X specific additions was very positive and we believe impact of the Render extension, the limitations of the provides a powerful tool that could be used in the analy- LBX extension and help identify specific application and sis of other widely used protocols. toolkit performance problems. We believe this analysis With measurement tools in hand, we set about char- technique can be usefully applied to other network pro- acterizing the performance of a significant selection of tocols.