Recent processors rely on huge pages to reduce the cost
of virtual-to-physical address translation. However, huge
pages are notorious for creating memory bloat – a phenomenon
wherein the OS ends up allocating more physical
memory to an application than its actual requirement.
This extra memory can be reclaimed by the OS
via de-bloating at runtime. However, we find that current
OS-level solutions either lack support for dynamic memory
de-bloating, or suffer from performance and fairness
pathologies while de-bloating.
We address these issues with EMD (Efficient Memory
De-bloating). The key insight in EMD is that different
regions in an application’s address space exhibit
different amounts of memory bloat. Consequently, the
tradeoff between memory efficiency and performance
varies significantly within a given application e.g., we
find that memory bloat is typically concentrated in specific
regions, and de-bloating them leads to minimal
performance impact. Hinged on this insight, EMD employs
a prioritization scheme for fine-grained, efficient,
and fair reclamation of memory bloat. EMD improves
performance by up to 69% compared to HawkEye — a
state-of-the-art OS-based huge page management system.
EMD also eliminates fairness concerns associated
with dynamic memory de-bloating.