Current isotach systems projects include the DARPA sponsored
build of a prototype isotach system; an NSF sponsored study of delta cache
coherence protocols; and Army Simtech/NGIC sponsored work on isotach based
parallel production (rule-based) systems.
The isotach prototype project is building
a prototype isotach system designed to implement isotach logical time in
a way that is efficient and scalable. The tasks of maintaining isotach
logical time and ordering messages is done in hardware by special isotach-specific
devices, but the prototype consists primarily of commodity parts: PCs running
Linux interconnected with Myrinet.
An initial version of the prototype gives low cost message ordering even
though this initial version emulates the functionality of the isotach specific
components in software.
Isotach networks support a family of cache coherence protocols called
delta cache protocols that are more concurrent that other directory protocols.
Delta cache protocols
|Delta Cache Protocols
support multiple concurrent reads and writes to the same cache block;
allow processes to pipeline memory accesses without sacrificing sequential
allow processes to read and write multiple shared cache blocks atomically
without obtaining exclusive access right to the accessed blocks.
The delta cache project is studying the performance of delta cache protocols,
exploring extensions of the protocols, and writing a compiler targeting
The IsoRule project is exploring the application of isotach technology
to the problem of speeding up the execution of production (rule-based)
systems. Isorule is an asynchronous parallel production system that uses
isotach ordering properties to ensure that each rule fires atomically.
Since rules fire atomically, execution can be asynchronous without risk
of an incorrect (unserializable) execution. The asynchronous approach to
parallel production systems avoids the synchronization bottleneck represented
by the traditional Match/Recognize/Act cycle. The project is implementing
IsoRule on top of an initial version of the isotach prototype.