A Case for Alternative Nested Paging Models for Virtualized Systems

Address translation often emerges as a critical performance bottleneck for virtualized systems and has recently been the impetus for hardware paging mechanisms. These mechanisms apply similar translation models for both guest and host address translations. We make an important observation that the model employed to translate from guest physical addresses (GPAs) to host physical addresses (HPAs) is in fact orthogonal to the model used to translate guest virtual addresses (GVAs) to GPAs. Changing this model requires VMM cooperation, but has no implications for guest OS compatibility. As an example, we consider a hashed page table approach for GPAHPA translation. Nested paging, widely considered the most promising approach, uses unhashed multi-level forward page tables for both GVAGPA and GPAHPA translations, resulting in a potential O(n2) page walk cost on a TLB miss, for n-level page tables. In contrast, the hashed page table approach results in an expected O(n) cost. Our simulation res...

• Type: Journal
• Year: 2010
• Where: CAL
• Authors: Giang Hoang, Chang Bae, Jack Lange, Lide Zhang, Peter A. Dinda, Russ Joseph
• Keywords: CAL 2010, Hashed Page Table, Page Table, Page Table Approach, Software Engineering