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Rethinking Memory Management: From Latency Tolerance to Scalable Eviction

Series: Department Seminar

Speaker: Prof. Sanidhya Kashyap, EPFL, Switzerland

Date/Time: Jan 14 11:00:00

Location: CSA Auditorium, (Room No. 104, Ground Floor)

Abstract:
Modern systems increasingly use heterogeneous memory, from tiered CXL to disaggregated far memory. This new landscape exposes critical flaws in traditional OS management, which was not designed for such diversity in latency and bandwidth, leading to severe performance and scalability bottlenecks.
First, we explore an ongoing challenge in tiered memory: the inflexible policy of existing systems. They focus rigidly on reducing latency (page migration), overlooking the significant potential to tolerate it. We are investigating a more flexible solution that integrates both strategies, proposing a dynamic approach that chooses to either migrate data (reduce) or use tier-aware prefetching (tolerate) based on real-time data hotness and hardware contention.
However, making the right policy choice is only half the battle; the OS must also provide a mechanism that can execute these decisions at scale. This leads to our second focus: a complete solution for the critical scalability bottleneck in page-based far memory. Existing systems fail at high thread counts due to inefficient coordination between page fault-in (latency-sensitive) and eviction (throughput-sensitive). We propose three principles that balance these paths by decoupling them, pipelining eviction, and using coordination-avoiding data structures to eliminate critical-path overhead.
Together, these efforts offer a comprehensive framework for managing modern memory. We argue for a fundamental shift that tackles both: a flexible policy to tolerate latency and a high-throughput mechanism to manage data. Our work provides a clear path forward on both fronts, enabling systems to capitalize on the promise of modern memory, finally.

Speaker Bio:
Dr. Sanidhya Kashyap is an Assistant Professor in the School of Computer and Communication Sciences at EPFL, where he leads research on robust and scalable systems software. His work, which spans operating systems, file systems, and system security, has been published in top-tier conferences like SOSP and OSDI. Dr. Kashyap is a recipient of the VMware Early Career Faculty award and earned his Ph.D. from Georgia Tech in 2020.

Host Faculty: Arkaprava Basu