Publications by Willy Zwaenepoel

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Graph processing systems are used in a wide variety of fields, ranging from biology to social networks, and a large number of such systems have been described in the recent literature. We perform a systematic comparison of various techniques proposed to sp ...

Clock-SI is a fully distributed protocol that implements snapshot isolation (SI) for partitioned data stores. It derives snapshot and commit timestamps from loosely synchronized clocks, rather than from a centralized timestamp authority as used in current ...

The performance of the networking stack in an operating system depends on the overhead incurred by two of its components: the per-byte overhead incurred in data-touching operations, and the per-packet overhead of protocol processing and other operating sys ...

Geo-replicated data platforms are at the backbone of several large-scale online services. Transactional Causal Consistency (TCC) is an attractive consistency level for building such platforms. TCC avoids many anomalies of eventual consistency, eschews the ...

This paper is concerned with performance debugging of multi- tier applications, such as commonly found in servers and dynamic-content web sites. Existing tools and techniques for profiling such applications are not general enough to track and profile trans ...

BEST PAPER AWARDIn this paper, we propose and evaluate three techniques for optimizing network performance in the Xen virtualized environment. Our techniques retain the basic Xen architecture of locating device dri ...

GentleRain is a new causally consistent geo-replicated data store that provides throughput comparable to eventual consistency and superior to current implementations of causal consistency. GentleRain uses a periodic aggregation protocol to deter- mine whet ...

This paper investigates the problem of deriving a white box performance model of Hardware Transactional Memory (HTM) systems. The proposed model targets TSX, a popular implementation of HTM integrated in Intel processors starting with the Haswell family in ...

This paper presents hardware and software mechanisms to enable concurrent direct network access (CDNA) by operating systems running within a virtual machine monitor. In a conventional virtual machine monitor, each operating system running within a virtual ...

In a modern data center (DC), a large majority of costs arise from energy consumption. The most popular technique used to mitigate this issue is virtualization and more precisely virtual machine (VM) consolidation. Although consolidation may increase serve ...

This paper addresses the problem of efficient scheduling of large clusters under high load and heterogeneous workloads. A heterogeneous workload typically consists of many short jobs and a small number of large jobs that consume the bulk of the cluster's r ...

Causal consistency is an attractive consistency model for geo-replicated data stores. It is provably the strongest model that tolerates network partitions. It avoids the long latencies associated with strong consistency, and, especially when using read-onl ...

Geo-replicated data platforms are the backbone of several large-scale online services. Transactional Causal Consistency (TCC) is an attractive consistency level for building such platforms. TCC avoids many anomalies of eventual consistency, eschews the syn ...

Current cluster computing frameworks suffer from load imbalance and limited parallelism due to skewed data distributions, processing times, and machine speeds. We observe that the underlying cause for these issues in current systems is that they partition ...

Instead of writing SQL queries directly, programmers often prefer writing all their code in a general purpose programming language like Java and having their programs be automatically rewritten to use database queries. Traditional tools such as object-rela ...

Causeway provides runtime support for the development of distributed meta-applications. These meta-applications control or analyze the behavior of multi-tier distributed applications such as multi-tier web sites or web services. Examples of meta-applicatio ...

Generalized snapshot isolation extends snapshot isolation as used in Oracle and other databases in a manner suitable for replicated databases. While (conventional) snapshot isolation requires that transactions observe the “latest” snapshot of the database, ...

Many distributed storage systems are transactional and a lot of work has been devoted to optimizing their performance, especially the performance of read-only transactions that are considered the most frequent in practice. Yet, the results obtained so far ...

In a virtualized environment, device drivers are often run inside a virtual machine (VM) rather than in the hypervisor. Doing so protects the hypervisor from bugs in the driver, and also allows the reuse of the device driver and its support infrastructure ...

Modern operating systems create ephemeral virtual-to-physical mappings for a variety of purposes, ranging from the implementation of interprocess communication to the implementation of process tracing and debugging. With succeeding generations of processor ...

Willy Zwaenepoel

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Everything You Always Wanted to Know about Multicore Graph Processing but Were Afraid to Ask

Clock-SI: Snapshot Isolation for Partitioned Data Stores Using Loosely Synchronized Clocks

Optimizing TCP Receive Performance

PaRiS: Causally Consistent Transactions with Non-blocking Reads and Partial Replication

Whodunit: Transactional Profiling for Multi-Tier Applications

Optimizing Network Virtualization in Xen

GentleRain: Cheap and Scalable Causal Consistency with Physical Clocks

An Analytical Model of Hardware Transactional Memory

Concurrent Direct Network Access for Virtual Machine Monitors

Drowsy-DC: Data center power management system

Hawk: Hybrid Datacenter Scheduling

Causal Consistency and Latency Optimality: Friend or Foe? [Extended Version]

PaRiS: Causally Consistent Transactions with Non-blocking Reads and Partial Replication

Rock You like a Hurricane: Taming Skew in Large Scale Analytics

JReq: Database Queries in Imperative Languages

Causeway: Support for Controlling and Analyzing the Execution of Web-Accessible Applications

Database Replication Using Generalized Snapshot Isolation

Distributed Transactions: Dissecting the Nightmare

TwinDrivers: Semi-Automatic Derivation of Fast and Safe Hypervisor Network Drivers from Guest OS Drivers

A Portable Kernel Abstraction for Low-Overhead Ephemeral Mapping Management