FlowTT: Exploiting Computation Flow Reuse in Irregular Tensor-Train Embedding
Tensor-Train (TT) decomposition effectively compresses large embedding tables in recommendation models, but TT-based embedding lookup remains inefficient because partially shared computation flows across input indices are not fully reused and intermediate results are repeatedly materialized off-chip between sequential TT-core contractions. We present FlowTT, a flow-aware GPU execution framework that reformulates TT gather as a set of prefix-shared irregular computation flows. FlowTT combines flow-aligned prefix-based index grouping, a fused TT-embedding execution path with on-chip intermediate retention, and persistent-thread scheduling with chunk-based work stealing and L2 checkpointing to preserve reuse under skewed workloads. By co-designing task formation, data buffering, and scheduling with the structure of TT gather, FlowTT reduces redundant TT-core operations, global-memory traffic, and load imbalance. On Meta's synthetic recommendation benchmarks (Meta-240, Meta-480, and Meta-788), FlowTT consistently achieves the lowest latency compared to existing methods. At batch size 32,768, it reduces latency by up to 42.2% in inference and 49.2% in training relative to EcoRec, while also achieving the lowest inference peak memory usage. These results show that exposing prefix-shared computation is key to efficient TT-based embedding execution.