arXiv subjects

Clément Burgelin

Publications and source records attributed to Clément Burgelin.

4 recordsLinked to original sources

arXiv2026

KCensus: Synthesizing Latency-Optimal Consensus Fast Paths (Extended Version)

Strongly consistent geo-replication often relies on fast paths to reduce latency in the common case of no failures or contention. Existing fast-path schemes, however, are ad hoc and restrictive: each corresponds to a point in a broad design space shaped by network topology, workload, and latency objective, so no single scheme works best across settings. This paper looks at fast-path schemes from a new perspective, as mechanisms that spread knowledge about proposals. With this view, we identify a fundamental condition on the spread of knowledge for a fast-path scheme to work. We then introduce KCensus, a framework that turns this condition into an optimization problem, synthesizing new fast-path schemes that are optimal for a given setting. We use KCensus to build a geo-replicated key-value store and evaluate it across AWS regions. Our system outperforms competing protocols, with up to 16% lower average latency.

cs.DC↗

arXiv2026

ThreadShift: Transparent Thread-Level Offloading on Transient Cloud Resources Using MPKs

Transient cloud resources offer significant cost savings, but their unpredictability makes them hard to use for applications that cannot be safely restarted after reclamation. Existing approaches require application changes or rely on coarse-grained checkpointing, whose cost limits its benefits. We present ThreadShift, a system that transparently offloads compute-intensive threads of unmodified Linux applications to cheap transient resources while preserving correctness under reclamation. By operating at thread granularity, ThreadShift enables fast, fine-grained checkpointing and offloads only the threads that benefit from transient execution. The main challenge is to checkpoint individual threads despite cross-thread dependencies. ThreadShift does so by efficiently tracking memory dependencies, identifying per-thread memory writes, and maintaining coherence across machines. Three novel uses of Memory Protection Keys (MPKs) make these mechanisms efficient, enabling fast incremental checkpoints without pausing the entire application. We implement ThreadShift on x86-64 Linux and evaluate it on workloads including machine-learning inference, cryptographic tasks, and in-memory data processing. ThreadShift offloads threads in as little as 164 us, performs checkpointing up to three orders of magnitude faster than CRIU, and reduces deployment cost by up to 56% on commodity clouds.

cs.DC↗

arXiv2024

SWARM: Replicating Shared Disaggregated-Memory Data in No Time

Memory disaggregation is an emerging data center architecture that improves resource utilization and scalability. Replication is key to ensure the fault tolerance of applications, but replicating shared data in disaggregated memory is hard. We propose SWARM (Swift WAit-free Replication in disaggregated Memory), the first replication scheme for in-disaggregated-memory shared objects to provide (1) single-roundtrip reads and writes in the common case, (2) strong consistency (linearizability), and (3) strong liveness (wait-freedom). SWARM makes two independent contributions. The first is Safe-Guess, a novel wait-free replication protocol with single-roundtrip operations. The second is In-n-Out, a novel technique to provide conditional atomic update and atomic retrieval of large buffers in disaggregated memory in one roundtrip. Using SWARM, we build SWARM-KV, a low-latency, strongly consistent and highly available disaggregated key-value store. We evaluate SWARM-KV and find that it has marginal latency overhead compared to an unreplicated key-value store, and that it offers much lower latency and better availability than FUSEE, a state-of-the-art replicated disaggregated key-value store.

cs.DC↗

arXiv2024

DSig: Breaking the Barrier of Signatures in Data Centers

Data centers increasingly host mutually distrustful users on shared infrastructure. A powerful tool to safeguard such users are digital signatures. Digital signatures have revolutionized Internet-scale applications, but current signatures are too slow for the growing genre of microsecond-scale systems in modern data centers. We propose DSig, the first digital signature system to achieve single-digit microsecond latency to sign, transmit, and verify signatures in data center systems. DSig is based on the observation that, in many data center applications, the signer of a message knows most of the time who will verify its signature. We introduce a new hybrid signature scheme that combines cheap single-use hash-based signatures verified in the foreground with traditional signatures pre-verified in the background. Compared to prior state-of-the-art signatures, DSig reduces signing time from 18.9 to 0.7 us and verification time from 35.6 to 5.1 us, while keeping signature transmission time below 2.5 us. Moreover, DSig achieves 2.5x higher signing throughput and 6.9x higher verification throughput than the state of the art. We use DSig to (a) bring auditability to two key-value stores (HERD and Redis) and a financial trading system (based on Liquibook) for 86% lower added latency than the state of the art, and (b) replace signatures in BFT broadcast and BFT replication, reducing their latency by 73% and 69%, respectively

cs.CR↗