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Published 20 hours ago • verified publisher icon verilog-to-routing

6D router lookahead and 3D custom switch block conflicts

Open saaramahmoudi opened this issue 1 year ago • 4 comments

My branch (3d_track_to_track_conn) is working with 6d_router_lookahead for 3D custom switchblocks. The last commit id from 6D_router_lookahead that I merged with my branch is "c3a247092cf66167c4eb3b0c7d91fefecabb1fb2". Up to this commit, an 3D architecture with only switch block connections across dice was working properly. However, after 6d_router_lookahead with master branch, routing always errors out if there is no OPIN connection between dice even for a very large channel width (e.g., 1600).

Expected Behaviour

Routing stage should be completed with only switch block 3D connections.

Current Behaviour

Routing always fails for nets travelling across dice even for a very small circuits and very large channel width. The same circuit and architecture (attached below) used to route with channel width 60 without a problem. Now, router just errors out that no possible path exists. I have generated RR graph for both master branch and my branch commit id (1370c03) that was working before, the RR graphs are identical.

Architecture and Design Files

  • arch file: 3D S4 with custom 3D switch blocks
  • design file: alu4.blif, mult_5x6.blif
  • vpr command line used: ./vpr ../vtr_flow/arch/multi_die/stratixiv_arch.timing.xml ../vtr_flow/benchmarks/blif/alu4.blif --route_chan_width 60 --pack --place --route

saaramahmoudi avatar Nov 30 '23 20:11 saaramahmoudi

@vaughnbetz this is the issue to track 6d_router_lookahead and custom 3D switch blocks conflict.

saaramahmoudi avatar Nov 30 '23 20:11 saaramahmoudi

Thanks for the detailed issue @saaramahmoudi . This should make it a lot easier to find ... an error out condition like this sounds like the lookahead builder is pruning some connection/option.

vaughnbetz avatar Dec 01 '23 03:12 vaughnbetz

Thanks Sara for flagging the problem. In this PR, I have addressed the issue. I am running QoR to make sure it doesn't affect the run-time for 2D architecture. Feel free to merge it to your branch (I tested it, and it was passing the case that you mentioned).

amin1377 avatar Dec 02 '23 22:12 amin1377

Great, thanks! Changed the title from costume to custom switch blocks :).

vaughnbetz avatar Dec 02 '23 22:12 vaughnbetz