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Arm Cortex-A55 Core Technical Reference Manual : About the L1 memory system

About the L1 memory system

The Cortex®-A55 core's L1 memory system enhances core performance and power efficiency.

It consists of separate instruction and data caches. You can configure instruction and data caches independently during implementation to sizes of 16KB, 32KB, or 64KB.

L1 instruction-side memory system

The L1 instruction-side memory system provides an instruction stream to the DPU. Its key features are:

  • 64-byte instruction side cache line length.
  • 4-way set associative L1 instruction cache.
  • 128-bit read interface to the L2 memory system.

The Cortex-A55 core uses extensive branch prediction to improve Instructions Per Clock (IPC) and power efficiency.

L1 data-side memory system

The L1 data-side memory system responds to load and store requests from the DPU. It also responds to SCU snoop requests from other cores, or external masters. Its key features are:

  • 64-byte data side cache line length.
  • 4-way set associative L1 data cache.
  • Read buffer that services both the Data Cache Unit (DCU), and the Instruction Fetch Unit (IFU).
  • 64-bit read path from the data L1 memory system to the datapath.
  • 128-bit write path from the datapath to the L1 memory system.
  • Merging store buffer capability which writes to all types of memory (device, normal cacheable and normal non-cacheable).
  • Data side prefetch engine that detects patterns of strides with multiple streams are allowed in parallel, capable of detecting both constant and patterns of strides.