ISMM 2021
Tue 22 Jun 2021 PLDI
co-located with PLDI 2021

Virtual-to-physical memory translation is becoming an increasingly dominant cost in workload execution; as data sizes scale, up to four memory accesses are required per translation, and 24 in virtualised systems. However, the radix trees in use today to hold these translations have many favorable properties, including cacheability, ability to fit in conventional 4kiB page frames, and a sparse representation, and so they are unlikely to be replaced in the near future.

In this paper we argue that these structures are actually too sparse for modern workloads, so many of the overheads are unnecessary. Instead, where appropriate, we expand groups of 4kiB layers, each able to translate 9 bits of address space, into a single 2MiB layer, able to translate 18 bits in a single memory access. These fit in the standard huge-page allocations used by most conventional operating systems and architectures. With minor extensions to the page-table-walker structures to support these, and aid in their cacheability, we can reduce memory accesses per walk by 27%, or 56% for virtualised systems, without significant memory overhead.

Conference Day
Tue 22 Jun

Displayed time zone: Eastern Time (US & Canada) change

13:30 - 16:15
Session 2: Paging/Structuring & Session 3: Allocating/Copying ISMM 2021 at ISMM
Chair(s): Doug LeaState University of New York (SUNY) Oswego, Benjamin ZornMicrosoft Research
13:30
30m
Talk
Radiant: Efficient Page Table Management for Tiered Memory Systems
ISMM 2021
DOI Pre-print
14:00
30m
Talk
Compendia: Reducing Virtual-Memory Costs via Selective Densification
ISMM 2021
Sam AinsworthUniversity of Edinburgh, UK, Timothy M. JonesUniversity of Cambridge, UK
Pre-print Media Attached
14:30
45m
Meeting
ISMM Business Meeting
ISMM 2021
Tobias WrigstadUppsala University, Sweden
15:15
30m
Talk
Adaptive Huge-Page Subrelease for Non-Moving Memory Allocators in Warehouse-Scale Computers
ISMM 2021
Martin MaasGoogle Research, Chris KennellyGoogle, Khanh NguyenTexas A&M University, Darryl GoveGoogle, Kathryn S McKinleyGoogle, Paul TurnerGoogle
15:45
30m
Talk
automemcpy A framework for automatic generation of fundamental memory operations
ISMM 2021
Guillaume ChateletGoogle Research, Chris KennellyGoogle, Sam XiGoogle, Ondrej SykoraGoogle Research, Clement CourbetGoogle Research, David LiGoogle, Bruno De BackerGoogle Research
DOI Pre-print