Review

Predictable Accelerator Design with Time-Sensitive Affine Types

• Why Fuse generates C/C++ codes since it's designed for Verilog?

• If "traditional HLS tools...allow uneven banking and silently insert additional hardware to account for the complicated access patterns that it induces". Why this time we won't have any complicated access pattern?

• A[1] is equivalent to A{1}[0]. How about A[3] given decl A:float[10 bank 2]?

• A question I remember asked by Chris was even though Fuse can constrain the syntax to be "safe", in real world, it would still be contrained by FPGA resources.

• Highligted blocks? suffix or prefix?

Review: Predictable Accelerator Design with Time-Sensitive Affine Types

• Abstract

  • Despite its restrictiveness, Dahlia admits hardware implementations that are nearly as efficient as designs from traditional HLS. Sounds weak. It sounds like we are trying to compare HLS and Dahlia in efficiency, which is misleading.

  • it can express 18 benchmarks from MachSuite. I guess this will be modified anyway.

  • Try to conclude "even though Fuse can constrain the syntax to be "safe", in real world, it would still be contrained by FPGA resources, why do people want to use Dahlia?"

• Intro

  • it is too explicit and verbose for productive engineering in most cases. Give example whenever trying to illustrate a point.

  • If possible, can we add graph of HLS because PL people may not know it?

  • Talk more about HLS limitations. Examples/experiments like when it goes wrong.

  • Previous research has shown how to apply sub-structural type systems to model classic computational re-sources such as memory allocations and file handles [24, 9, 36, 49] and to enforce exclusion for safe shared-memory par-allelism [23, 8, 14]. ???

  • imperative erasure What does that mean?

• HLS vs Dahlia

  • Figure 2(a). in[10] -> out[10]

  • How about a type to compare cycles and hardware overhead for three designs?

  • What will happen if no array partition is placed?

  • In design principle (2.2), is there a way to mention view and order composition (; and --- )as one of the important selling point? Explain why do we want to include have order composition and why do we want to use view should be reflected in design principle. Why time-sensitive affine types is not mentioned here?

  • Why design principle belongs to section HLS vs Dahlia? Can we summarize with a table to learn the difference between HLS and dahlia?

Spatial

• Resource usage.

• There are some mechanism users cannot control due to automation. E.g. Spatial has its own banking decision. Users can only specify the unrolling factor. Dahlia is more transparant. It tries to generate designs following your instruction.

• It turns out Spatial's banking decision is not great. See the abrupt increase of LUT given certain unrolling (see DSP usage) and banking decision.

• Even with perfect DSE tool, automation can only output one point on pareto curve. Dahlia is trying to guide users to give possible designs on / close to pareto curve.