c1e168fdbe
+ Microarchitecture optimizations + 64-bit support + Xilinx FPGA support + LLVM-16 support + Refactoring and quality control fixes minor update minor update minor update minor update minor update minor update cleanup cleanup cache bindings and memory perf refactory minor update minor update hw unit tests fixes minor update minor update minor update minor update minor update minor udpate minor update minor update minor update minor update minor update minor update minor update minor updates minor updates minor update minor update minor update minor update minor update minor update minor updates minor updates minor updates minor updates minor update minor update
70 lines
2.2 KiB
Markdown
70 lines
2.2 KiB
Markdown
# Vortex Cache Subsystem
|
||
|
||
The Vortex Cache Sub-system has the following main properties:
|
||
|
||
- High-bandwidth with bank parallelism
|
||
- Snoop protocol to flush data for CPU access
|
||
- Generic design: Dcache, Icache, Shared Memory, L2 cache, L3 cache
|
||
|
||
### Cache Hierarchy
|
||
|
||
|
||
|
||
- Cache can be configured to be any level in the hierarchy
|
||
- Caches communicate via snooping
|
||
- Cache flush from AFU is passed down the hierarchy
|
||
|
||
### VX_cache.v (Top Module)
|
||
|
||
VX.cache.v is the top module of the cache verilog code located in the `/hw/rtl/cache` directory.
|
||
|
||
|
||
|
||
- Configurable (Cache size, number of banks, bank line size, etc.)
|
||
- I/O signals
|
||
- Core Request
|
||
- Core Rsp
|
||
- DRAM Req
|
||
- DRAM Rsp
|
||
- Snoop Rsp
|
||
- Snoop Rsp
|
||
- Snoop Forwarding Out
|
||
- Snoop Forwarding In
|
||
- Bank Select
|
||
- Assigns valid and ready signals for each bank
|
||
- Snoop Forwarder
|
||
- DRAM Request Arbiter
|
||
- Prepares cache response for communication with DRAM
|
||
- Snoop Response Arbiter
|
||
- Sends snoop response
|
||
- Core Response Merge
|
||
- Cache accesses one line at a time. As a result, each request may not come back in the same response. This module tries to recombine the responses by thread ID.
|
||
|
||
### VX_cache_bank.v
|
||
|
||
VX_cache_bank.v is the verilog code that handles cache bank functionality and is located in the `/hw/rtl/cache` directory.
|
||
|
||
|
||
|
||
- Allows for high throughput
|
||
- Each bank contains queues to hold requests to the cache
|
||
- I/O signals
|
||
- Core request
|
||
- Core Response
|
||
- DRAM Fill Requests
|
||
- DRAM Fill Response
|
||
- DRAM WB Requests
|
||
- Snp Request
|
||
- Snp Response
|
||
- Request Priority: DRAM fill, miss reserve, core request, snoop request
|
||
- Snoop Request Queue
|
||
- DRAM Fill Queue
|
||
- Core Req Arbiter
|
||
- Requests to be processed by the bank
|
||
- Tag Data Store
|
||
- Registers for valid, dirty, dirtyb, tag, and data
|
||
- Length of registers determined by lines in the bank
|
||
- Tag Data Access:
|
||
- I/O: stall, snoop info, force request miss
|
||
- Writes to cache or sends read response; hit or miss determined here
|
||
- A missed request goes to the miss reserve if it is not a snoop request or DRAM fill |