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Shigeki Tomishima

Publications and source records attributed to Shigeki Tomishima.

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PIMID: A Full-System Simulator with Intricacy and Diversity for Processing-in-Memory

Processing-in-Memory addresses the memory wall by co-locating computation with memory, but because real PIM hardware remains scarce, simulation is the primary way to explore the PIM design space. Yet existing PIM simulators each cover only part of that space: they typically model a single memory technology, fix processing elements at one level of the memory hierarchy, support a single execution model, and stop at the device boundary. We therefore present PIMID, an execution- and trace-driven full-system simulator that closes these gaps in one tool. PIMID supports both the shared-memory and message-passing execution models, running annotated parallel code in OpenMP and MPI side by side across eleven memory technologies (seven DRAM standards, SRAM, and three non-volatile memories); it places PEs anywhere from subarrays to logic dies, sweeps PE count and core-model fidelity, and prices the in-memory network per technology from measured congestion. Its single-process host-device co-simulation resolves an end-to-end time and energy breakdown (host preparation, device compute, and explicit boundary charges) that device-only tools cannot produce. Across the resulting dual-execution-model dataset, PIMID shows that the memory technology alone moves execution time by more than an order of magnitude and that the best host main memory is not the best PIM substrate; that regular kernels scale superlinearly with PE count as in-memory bandwidth co-scales with compute; that graph traversal under message-passing hits a collective-communication wall absent under shared memory; and that at full-system scope the offload trades time for energy only on the bandwidth-class memory: shared-memory offload saves energy on HBM3 while a 16-core host keeps every end-to-end time win. PIMID's plugin interfaces let new engines and models be added through standardized YAML specifications as PIM technology evolves.

cs.AR

Enabling Homomorphically Encrypted Inference for Large DNN Models

The proliferation of machine learning services in the last few years has raised data privacy concerns. Homomorphic encryption (HE) enables inference using encrypted data but it incurs 100x-10,000x memory and runtime overheads. Secure deep neural network (DNN) inference using HE is currently limited by computing and memory resources, with frameworks requiring hundreds of gigabytes of DRAM to evaluate small models. To overcome these limitations, in this paper we explore the feasibility of leveraging hybrid memory systems comprised of DRAM and persistent memory. In particular, we explore the recently-released Intel Optane PMem technology and the Intel HE-Transformer nGraph to run large neural networks such as MobileNetV2 (in its largest variant) and ResNet-50 for the first time in the literature. We present an in-depth analysis of the efficiency of the executions with different hardware and software configurations. Our results conclude that DNN inference using HE incurs on friendly access patterns for this memory configuration, yielding efficient executions.

cs.CR