[Router] Upstream Fine-Grained Parallel Router (FPT'24) #2920
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Upstreamed the fine-grained parallel router implementation into the VTR master. The original branch is https://github.com/verilog-to-routing/vtr-verilog-to-routing/tree/mq-parallel-router. Modified the MultiQueue (SPAA'24) implementation and integrated it into the VTR codebase.
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VPR
The original FG parallel router used to use boost. VTR does not install boost by default. Moved to STL instead.
Added a partial abstract class for ConnectionRouter, derived from the pure abstract ConnectionRouterInterface. The SerialConnectionRouter and ParallelConnectionRouter classes are now derived from the ConnectionRouter class, utilizing the common class members and helper functions to reduce code duplication.
Added Doxygen-style code comments and documentation for connection routers, including the ConnectionRouter abstract class, the Parallel- ConnectionRouter concrete class, and the SerialConnectionRouter concrete class. Updated the helper messages for command-line options added for parallel connection router.
Fixed the interface issues of ConnectionRouter in NestedNetlistRouter. Fixed code formats. Fixed typo in read_options.cpp.
Updated the command-line usage for parallel connection router in both Read the Docs and read_options.cpp.
Added regression tests for parallel connection router by appending extra sets of configurations to those VTR flow regression tests previously selected by Fahri for testing coarse-grained parallel router. Removed VPR connection router test (vpr/test/test_connection_router.cpp), since it has been out-dated for a very long time and has caused lots of trouble for running VPR C++ tests locally.
Fixed a weird code formatting issue in libs/librtlnumber/src/include/ internal_bits.hpp. GitHub CI said the file failed dev/check-format.sh, however, the same script runs perfectly in my local environment. Double checked the version of clang-format, which seemed to be the same as CI. Directly copied the file from the GitHub repo to resolve this issue.
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Hi @ueqri
These changes are looking great! I have left some comments.
You mentioned to me that the parallel router code was not 100% commented yet, so I will review that after you give me the go ahead.
The `No source in route tree` bug in ParallelConnectionRouter (since commit 875b98e) has been fixed. It turns out that putting another member variable `MultiQueueDAryHeap<HeapImplementation::arg_D> heap_` in the derived class ParallelConnectionRouter together with the existing `HeapImplementation heap_` in the base class ConnectionRouter causes the issue. The solution is to keep `heap_` only in the base class and use `ConnectionRouter<MultiQueueDAryHeap<HeapImplementation::arg_D>>` rather than `ConnectionRouter<HeapImplementation>` for deriving the parallel connection router. Please note that ParallelConnectionRouter still has some bugs (i.e., getting stuck in the MultiQueue pop). This commit is not fully working. Please do not use it for any experiments. Updated the previously incorrect command-line options for the parallel connection router in the regression tests.
Fixed the weird bug in parallel connection router as mentioned in commit f73212c. The bug occurred because two function parameters 'num_threads' and 'num_queues' have been misplaced when instantiating the MQ_IO. This took two weeks to figure out exactly. The VTR benchmark (`vtr_reg_qor_chain` task) has been tested/passed for different cases (1) 'serial mode' 1T+2Q (1 thread, 2 queues), (2) 2T+4Q, and (3) 4T+2Q. The determinism has also been verified for the VTR benchmark.
Added more explanation to the command-line options messages and code comments. Cleaned up ParallelConnectionRouter-related codebase.
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Upstreamed the fine-grained parallel router implementation into the VTR master. The original branch is https://github.com/verilog-to-routing/vtr-verilog-to-routing/tree/mq-parallel-router.
Modified the MultiQueue (SPAA'24) implementation and integrated it into the VTR codebase.
VTR strong regression tests passed.
TODOs