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Programmable Temporal Isolation through Variable-Bandwidth Servers
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by Silviu S. Craciunas, Christoph Kirsch, Hannes Payer, Harald Roeck,
and Ana Sokolova
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Abstract:
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We introduce variable-bandwidth servers
(VBS) for scheduling and executing processes under programmable
temporal isolation. A VBS is an extension
of a constant-bandwidth server where throughput and
latency of process execution can not only be controlled to
remain constant across different competing workloads but
also to vary in time as long as the resulting bandwidth
stays below a given bandwidth cap. We have designed
and implemented a VBS-based EDF-style constant-time
scheduling algorithm, a constant-time admission test, and
four alternative queue management plugins which influence
the scheduling algorithm’s overall temporal and
spatial complexity. Experiments confirm the theoretical
bounds in a number of microbenchmarks and demonstrate
that the scheduler can effectively manage in constant time
any number of processes up to available memory while
maintaining response times of individual processes within a
bounded range. We have also developed a small-footprint,
bare-metal virtual machine that uses VBS for temporal
isolation of multiple, concurrently running processes executing
real code.
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