Software memory compression has been a common practice among operating systems. Since then, prior works have explored hardware memory compression to reduce the load on the CPU by offloading memory compression to hardware. However, prior works on hardware memory compression cannot provide critical isolation in multi-tenant systems like cloud servers. Our evaluation of prior work (TMCC) shows that a tenant can be slowed down by more than 12x due to the lack of isolation.
This work, Compressed Memory Management Unit (CMMU), prototypes hardware compression for multi-tenant systems. CMMU provides critical isolation for multi-tenant systems.First, CMMU allows OS to control individual tenants' usage of physical memory. Second, CMMU compresses a tenant's memory to an OS-specified physical usage target. Finally, CMMU notifies the OS to start swapping the memory to the storage if it fails to compress the memory to the target.
We prototype CMMU with a real compression module on an FPGA board. CMMU runs with a Linux kernel modified to support CMMU. The prototype virtually expands the memory capacity to 4X. CMMU stably supports the modified Linux kernel with multiple tenants and applications. While achieving this, CMMU only requires several extra cycles of overhead besides the essential data structure accesses. ASIC synthesis results show CMMU fits within 0.00931mm2 of silicon and operates at 3GHz while consuming 36.90mW of power. It is a negligible cost to modern server systems. / Master of Science / Memory is a critical resource in computer systems. Memory compression is a common technique to save memory resources. Memory compression consumes the computing resource, traditionally supplied by the CPU. In other words, memory compression traditionally competes with applications for CPU computing power. The prior work, TMCC, provides a design to perform memory compression in ASIC hardware, therefore no longer competing for CPU computing power. However, TMCC provides no isolation in a multitenant system like a modern cloud server.
This thesis prototypes a new design, Compressed Memory Management Unit (CMMU), providing isolation in hardware memory compression. This prototype can speed up applications by 12x compared to without the isolation, with a 4x expansion in virtual memory capacity. CMMU supports a modified Linux OS running stably. CMMU also runs at high clock speed and offers little overhead in latency, silicon chip area, and power
| Identifer | oai:union.ndltd.org:VTETD/oai:vtechworks.lib.vt.edu:10919/116523 |
| Date | 18 October 2023 |
| Creators | Liu, Yuqing |
| Contributors | Computer Science and Applications, Jian, Xun, Min, Chang Woo, Hicks, Matthew |
| Publisher | Virginia Tech |
| Source Sets | Virginia Tech Theses and Dissertation |
| Language | English |
| Detected Language | English |
| Type | Thesis |
| Format | ETD, application/pdf |
| Rights | In Copyright, http://rightsstatements.org/vocab/InC/1.0/ |
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