From software threads to parallel hardware with LegUp high-level synthesis
Bibliographic record
Abstract
High-level synthesis (HLS) can automatically synthesize software to hardware. With the design specification in software, HLS can reduce the lengthy design cycles of hardware, and make the performance and energy-efficiency benefits of hardware accessible to those without hardware skills. Since the introduction of the first C-based HLS tools more than a decade ago, however, the adaption of the technology has been slow by both software and hardware engineers. We attribute this to two key factors: 1) For hardware engineers, there is still a gap between HLS-generated hardware and human-designed hardware, partly due to the inability of HLS tools to fully exploit hardware parallelism, and 2) for software engineers, HLS remains to be a difficult endeavour, as many parts of the design, such as system integration, largely remain a manual process. This dissertation provides an HLS framework, LegUp, which seeks to address both issues. LegUp can compile an entire software program to hardware to produce a hardware-only system, or it can also automatically partition the program to generate a processor-accelerator hybrid system, wherein the compute-intensive program segments are accelerated by hardware, with the remaining segments executed in software on a processor. In both cases, a complete system is generated, including necessary memories and interconnect. To allow one to easily exploit hardware parallelism, we provide HLS support for synthesizing parallel software to parallel hardware. In particular, we support automatically compiling a multi-threaded program with Pthreads and OpenMP to parallel hardware accelerators that operate concurrently within a hardware-only or a processor-accelerator hybrid system. In the context of parallel hardware, we investigate architectural and memory optimizations that help to improve circuit performance and area, and discuss a method of using the producer-consumer pattern in software to infer a streaming circuit in hardware. With these techniques, we show that LegUp can produce high-performance hardware that can be competitive to circuits that are generated by commercial HLS tools, and demonstrate that LegUp-generated circuits can also outperform software executing on x86 processors.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.002 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.002 | 0.001 |
| Open science | 0.001 | 0.002 |
| Research integrity | 0.001 | 0.002 |
| Insufficient payload (model declined to judge) | 0.008 | 0.003 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".