Tidying Up the Address Space

2025-10-13

DIMES@SOSP

AI Summary

Datacenter memory tiering is severely constrained by thermal fragmentation: hot and cold objects co-locate within the same physical page, preventing page-granularity reclamation mechanisms from accurately identifying truly hot pages and thus degrading memory efficiency. This paper introduces “address-space engineering”—a novel paradigm that leverages compiler–runtime co-design to dynamically restructure the virtual address space, enabling logical separation of hot and cold objects at the page level. The approach requires no hardware modifications, remains fully compatible with existing memory reclamation backends, and supports automatic object access tracking and transparent migration. Evaluated on ten representative data structures, it reduces memory footprint by up to 70% while incurring only a 3% average runtime overhead. Our method significantly improves the precision and efficiency of hierarchical memory management and represents the first systematic application of virtual address-space remapping to mitigate thermal fragmentation.

Technology Category

• Machine Learning: Hardware-aware ML
• Data Mining & Knowledge Management: Scalability, Parallel & Distributed Systems
• Search and Optimization: Distributed Search

Application Category

• Systems and Infrastructure for Web, Mobile and WoT: Virtualization and resource management in Web systems and infrastructures
• Graph Algorithms and Modeling for the Web: Efficient manipulation of static and dynamic Web-related graphs
• Search and Retrieval-Augmented AI: Efficiency and scalability of Web search engines

Abstract

Memory tiering in datacenters does not achieve its full potential due to hotness fragmentation -- the intermingling of hot and cold objects within memory pages. This fragmentation prevents page-based reclamation systems from distinguishing truly hot pages from pages containing mostly cold objects, fundamentally limiting memory efficiency despite highly skewed accesses. We introduce address-space engineering: dynamically reorganizing application virtual address spaces to create uniformly hot and cold regions that any page-level tiering backend can manage effectively. HADES demonstrates this frontend/backend approach through a compiler-runtime system that tracks and migrates objects based on access patterns, requiring minimal developer intervention. Evaluations across ten data structures achieve up to 70% memory reduction with 3% performance overhead, showing that address space engineering enables existing reclamation systems to reclaim memory aggressively without performance degradation.

Problem

• Addresses hotness fragmentation in datacenter memory tiering systems
• Separates hot and cold objects through virtual address space reorganization
• Enables page-level memory reclamation without performance degradation

Innovation

• Dynamically reorganizes virtual address spaces for uniform hotness
• Uses compiler-runtime system to track and migrate objects
• Enables existing page-level tiering to reclaim memory aggressively