The expansion of long-context Large Language Models (LLMs) creates significant memory system challenges. While Processing-in-Memory (PIM) is a promising accelerator, we identify that it suffers from critical inefficiencies when scaled to long contexts: severe channel underutilization, performancelimiting I/O bottlenecks, and massive memory waste from static KV cache management. In this work, we propose PIMphony, a PIM orchestrator that systematically resolves these issues with three co-designed techniques. First, Token-Centric PIM Partitioning (TCP) ensures high channel utilization regardless of batch size. Second, Dynamic PIM Command Scheduling (DCS) mitigates the I/O bottleneck by overlapping data movement and computation. Finally, a Dynamic PIM Access (DPA) controller enables dynamic memory management to eliminate static memory waste. Implemented via an MLIR-based compiler and evaluated on a cycle-accurate simulator, PIMphony significantly improves throughput for long-context LLM inference (up to 72B parameters and 1M context length). Our evaluations show performance boosts of up to 11.3× on PIM-only systems and 8.4× on xPU+PIM systems, enabling more efficient deployment of LLMs in real-world long-context applications.

•Recap Accelerator-in-Memory (AiM) & AiMX •System Extensions of AiMX Card for Datacenter •AiM & AiMX for On-device AI •Design Choices for Future AiM/AiMX •Conclusion

Memory wall issue has become the overwhelming bottleneck of future systems due to the explosive parameter growth and low computing density large language model (LLM). Near-data processing (NDP) could alleviate data traffic and energy consumption, but the storage demand of LLM is still enormous. Weight sparsity is helpful for reducing data capacity. Unstructured sparsity sacrifices less accuracy compared to structured one, but the random non-zero values distribution in NDP leads to load imbalance among parallel processing units. Here we propose LauWS which is seamlessly combined into various prior arts of sparsity. LauWS follows the local characteristics of feature distribution in weight matrix for various models, preserving even tiny features and discarding non-feature values as far as possible region by region. That is the key for LauWS achieving a trade-off between high prune ratio (PR) and less accuracy loss (AL). Evaluations are carried out based on a GDDR6-based bank-NDP system. The typical optimization compared to the no-prune includes 38% speedup at 0.8PR with no AL for MLP, 22.7% speedup at 0.5PR with no AL for GPT-2, 23.6% speedup at 0.5PR with the lowest perplexity for OPT-125m.

This poster presents system architecture, software stack, and performance analysis for SK hynix’s very first GDDR6-based processing-in-memory (PIM) product sample, called Accelerator-in-Memory (AiM).AiM is designed for the in-memory acceleration of matrix-vector product operations, which are commonly found in machine learning applications. The strength of AiM primarily comes from the two design factors, which are 1) all-bank operation support and 2) extended DRAM command set. All-bank operations allow AiM to fully utilize the abundant internal DRAM bandwidth, which makes it an attractive solution for memory-bound applications. The extended command set allows the host to address these new operations efficiently and provides a clean separation of concerns between the AiM architecture and its software stack design.We present a dedicated FPGA-based reference platform with a software stack, which is used to validate AiM design and evaluate its system-level performance. We also demonstrate FMC-based AiM extension cards that are compatible with the off-the-shelf FPGA boards and serve as an open research platform allowing potential collaborators and academic institutes to access our hardware and software systems.