The Tree Machine: A Highly Concurrent Computing Environment
Read PDF →Browning, 1980
Category: Computer Architecture
Overall Rating
Score Breakdown
- Cross Disciplinary Applicability: 6/10
- Latent Novelty Potential: 4/10
- Obscurity Advantage: 4/5
- Technical Timeliness: 3/10
Synthesized Summary
This paper is a fascinating historical document demonstrating a specific approach to concurrent hardware design tailored to the limitations of early VLSI, focusing on communication costs.
While it explored the elegant idea of mapping tree-structured computational problems onto a physical tree, the specific architectural choices made (simple integer-only nodes, fixed tree topology, low-level explicit message passing) are fundamentally mismatched with modern computational demands and silicon capabilities.
Attempting to leverage this specific design for modern applications would mean rebuilding it using vastly different principles, negating the core contribution of the thesis itself.
Optimist's View
The core idea of a general-purpose architecture based on a binary tree of simple processors... is not a mainstream paradigm today.
the paper's detailed exploration of mapping various algorithms, particularly exhaustive search strategies for NP-complete problems, onto this hierarchical structure holds significant latent novelty.
Modern VLSI technology allows integrating millions, if not billions, of transistors, making the physical realization of such an architecture (or a similar one) with many more, possibly more powerful, processors feasible.
A modern "Tree Search Accelerator" could feature millions of simple processing elements, interconnected as a deep binary tree, with custom logic optimized for the specific "node" operations...
Skeptic's View
Its core tenets are rooted in assumptions and technological constraints that no longer hold, its contributions have been superseded, and its fundamental limitations make it ill-suited for contemporary computational challenges.
The thesis's communication model – strictly message passing on the tree edges – feels fundamentally limited in a world where shared memory, hardware-supported cache coherence... are common parallel programming abstractions, often mapped onto topologies far richer than a binary tree.
This thesis likely faded because the Tree Machine... failed to establish itself as a truly general-purpose highly concurrent architecture.
The processor design described... is exceedingly simple, lacking crucial features for modern computation... The lack of hardware support for floating-point is a fundamental limitation for almost any non-trivial modern application.
Final Takeaway / Relevance
Ignore