TileDRAM: Compiler-Controlled Tile-to-DRAM Layouts for 3D DRAM GPGPUs

Overview & Synopsis

Modern GPU compilers expose rich layout abstractions for mapping tensors to threads and on-chip resources, but compute-unit-local (CU-local) 3D DRAM architectures lack a corresponding abstraction for specifying how operand-tile data are arranged within the DRAM address space. Without such an abstraction, conventional placement under the existing DRAM address mapping can subject structured tile accesses to severe row-buffer conflicts. We present TileDRAM, a compiler-runtime toolchain that introduces tile-to-DRAM layouts as a compiler-visible abstraction for DRAM placement. TileDRAM extends the GPU Linear Layout abstraction from compute-side mapping targets to DRAM placement coordinates and selects layouts per tile access signature, using recurring tile-local access behavior as the specialization unit. Since row-buffer locality depends on ordered request history, TileDRAM evaluates candidate layouts through their row-buffer behavior under fixed DRAM address mappings. Accesses under the selected layouts are realized through ordinary address arithmetic, without new address-remapping hardware or ISA support. In full-trace replay on Accel-Sim/Ramulator2 across 108 mixture-of-experts (MoE) feed-forward network (FFN) cases, TileDRAM reduces the request-weighted row-conflict rate from 75.7% to 15.2% and achieves a 1.77x geomean speedup. Retargeting six traces to six 3D DRAM organizations yields a 2.20x geomean speedup under the same compiler abstraction. On an RTX 3090, address transformation adds 0.17% geomean overhead over identity.