USENIX Technical Program - Abstract - USENIX Annual
Conference, General Session - June 2000
Operating System Support for Multi-User, Remote, Graphical
Alexander Ya-li Wong and Margo Seltzer, Harvard University
The emergence of thin client computing and multi-user, remote, graphical
interaction revives a range of operating system research issues long
dormant, and introduces new directions as well. This paper investigates
the effect of operating system design and implementation on the
performance of thin client service and interactive applications. We
contend that the key performance metric for this type of system and its
applications is user-perceived latency and we give a structured approach
for investigating operating system design with this criterion in mind.
In particular, we apply our approach to a quantitative comparison and
analysis of Windows NT, Terminal Server Edition (TSE), and Linux with
the X Windows System, two popular implementations of thin client
We find that the processor and memory scheduling algorithms in both
operating systems are not tuned for thin client service. Under heavy CPU
and memory load, we observed user-perceived latencies up to 100 times
beyond the threshold of human perception. Even in the idle state, these
systems induce unnecessary latency. TSE performs particularly poorly
despite scheduler modifications to improve interactive responsiveness.
We also show that TSE's network protocol outperforms X by up to six
times, and also makes use of a bitmap cache which is essential for
handling dynamic elements of modern user interfaces and can reduce
network load in these cases by up to 2000%.
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