GMEM: Generalized Memory Management for Peripheral Devices

Abstract: This paper presents GMEM, generalized memory management, for peripheral devices. GMEM provides OS support for centralized memory management of both CPU and devices. GMEM provides a high-level interface that decouples MMU-specific functions. Device drivers can thus attach themselves to a process's address space and let the OS take charge of their memory management. This eliminates the need for device drivers to "reinvent the wheel" and allows them to benefit from general memory optimizations integrated by GMEM. Furthermore, GMEM internally coordinates all attached devices within each virtual address space. This drastically improves user-level programmability, since programmers can use a single address space within their program, even when operating across the CPU and multiple devices. A case study on device drivers demonstrates these benefits. A GMEM-based IOMMU driver eliminates around seven hundred lines of code and obtains 54% higher network receive throughput utilizing 32% less CPU compared to the state-of-the-art. In addition, the GMEM-based driver of a simulated GPU takes less than 70 lines of code, excluding its MMU functions.