The NVIDIA CUDA Direct Sparse Solver (cuDSS) is designed to tackle large-scale linear sparse problems in fields like Electronic Design Automation (EDA) and Computational Fluid Dynamics (CFD), which are becoming increasingly complex. cuDSS offers unprecedented scalability and performance by allowing users to run sparse solvers at a massive scale with minimal code changes. It leverages hybrid memory mode to utilize both CPU and GPU resources, enabling the handling of larger problems that exceed a single GPU's memory capacity. This approach allows for efficient computation even for problems with over 10 million rows and a billion nonzeros, by using 64-bit integer indexing arrays and optimizing memory usage across multiple GPUs or nodes. Hybrid memory mode in cuDSS addresses the memory limitations of a single GPU by using both CPU and GPU memories, albeit with a trade-off in data transfer time due to bus bandwidth. This mode is not enabled by default, but once activated, it allows the solver to manage device memory automatically or with user-defined limits. The performance of hybrid memory mode is influenced by the CPU/GPU memory bandwidth, but modern NVIDIA driver optimizations and fast interconnects help mitigate these impacts. By setting memory limits and utilizing the maximum GPU memory, users can achieve optimal performance, making it possible to solve larger problems efficiently. For even larger computational tasks, cuDSS supports multi-GPU mode (MG mode) and Multi-GPU Multi-Node (MGMN) mode, which allow the use of all GPUs in a node or across multiple nodes, respectively. MG mode simplifies the process by handling GPU communications internally, eliminating the need for developers to manage distributed communication layers. MGMN mode, on the other hand, requires a communication layer like Open MPI or NCCL, enabling the distribution of computations across multiple nodes. These modes allow for solving massive problems or speeding up computations by utilizing more GPUs, thereby accommodating the growing size and complexity of real-world problems. This matters because it provides a scalable solution for industries facing increasingly complex computational challenges.
