PARALLELGPUOS: A Concurrent OS-level GPU Checkpoint and Restore System using Validated Speculation

Abstract

Checkpointing (C) and restoring (R) are key components for GPU tasks. POS is an OS-level GPU C/R system: It can transparently checkpoint or restore processes that use the GPU, without requiring any cooperation from the application, a key feature required by modern systems like the cloud. Moreover, POS is the first OS-level C/R system that can concurrently execute C/R with the application execution: a critical feature that can be trivially achieved when the processes only running on the CPU, but becomes challenging when the processes use GPU. The problem is how to ensure consistency during concurrent execution with the lack of application semantics due to transparency. CPU processes can leverage OS and hardware paging to fix inconsistency without application semantics. Unfortunately, GPU bypasses OS and paging for high performance. POS fills the semantic gap by speculatively extracting buffer access information of GPU kernels during runtime. Thanks to the simple and well-structured nature of GPU kernels, our speculative extraction (with runtime validation) achieves 100% accuracy on applications from training to inference whose domains span from vision, large language models, and reinforcement learning. Based on the extracted semantics, we systematically overlap C/R with application execution, and achieves orders of magnitude higher performance under various tasks compared with the state-of-the-art OS-level GPU C/R, including training fault tolerance, live GPU process migration, and cold starts acceleration in GPU-based serverless computing.