X-Cache: A Modular Architecture for Domain-Specific Caches

Terminology:

• non-affine memeory access
• cache
  • data-structure walks
  • multiple refills
  • preloading
• data orchestration

Intro

Emerging DSAs target a broad set of applications characterized by

• Non-affine data structure

  DSAs typically organize data in DRAM with a minimal footprint. Hence, they employ sparse data structures, indirect-indexes, and hash tables. Getting an element's global address requires data structure traversal

• Dynamic accesses

  Both the data structure and loop pattern cause emerging DSAs to have dynamic (i.e. indirectly addressed) and irregular non-linear accesses. A cache is necessary to capture the reuse.

• Walkers

  Since data is stored in non-linear data structures, a walker is required to traverse and preload the cache. A single miss could trigger multiple nested preloads

• Explicit orchestration

  Finally, DSAs need to explicitly orchestrate cache replacement and refill with the computational datapaths.