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Willy Zwaenepoel

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Related publications (57)

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Performance Profiling of Virtual Machines

Willy Zwaenepoel, Jiaqing Du

Profilers based on hardware performance counters are indispensable for performance debugging of complex software systems. All modern processors feature hardware performance counters, but current virtual machine monitors (VMMs) do not properly expose them t ...

2011

Diagnosing Performance Overheads in the Xen Virtual Machine Environment

Willy Zwaenepoel

Virtual Machine (VM) environments (e.g., VMware and Xen) are experiencing a resurgence of interest for diverse uses including server consolidation and shared hosting. An application's performance in a virtual machine environ- ment can differ markedly from ...

2005

Don't cry over spilled records: Memory elasticity of data-parallel applications and its application to cluster scheduling

Willy Zwaenepoel, Syed Mohammad Aunn Raza, Calin Iorgulescu, Florin Dinu

Understanding the performance of data-parallel workloads when resource-constrained has significant practical importance but unfortunately has received only limited attention. This paper identifies, quantifies and demonstrates memory elasticity, an intrinsi ...

The USENIX Association2017

Dynamic Content Web Applications: Crash, Failover, and Recovery Analysis

Willy Zwaenepoel

This work assesses how crashes and recoveries affect the performance of a replicated dynamic content web application. RobustStore is the result of retrofitting TPC-W’s online bookstore with Treplica, a middleware for building dependable applications. Imple ...

2009

Queryll: Java Database Queries through Bytecode Rewriting

Willy Zwaenepoel, Christopher Ming-Yee Iu

When interfacing Java with other systems such as databases, programmers must often program in special interface languages like SQL. Code written in these languages often needs to be embedded in strings where they cannot be error-checked at compile-time, or ...

2006

Wren: Nonblocking Reads in a Partitioned Transactional Causally Consistent Data Store

Willy Zwaenepoel, Diego Didona, Kristina Spirovska

Transactional Causal Consistency (TCC) extends causal consistency, the strongest consistency model compatible with availability, with interactive read-write transactions, and is therefore particularly appealing for geo-replicated platforms. This paper pres ...

2018

Low-Overhead Dynamic Instruction Mix Generation using Hybrid Basic Block Profiling

Willy Zwaenepoel, Andrzej Pawel Nowak

Dynamic instruction mixes form an important part of the toolkits of performance tuners, compiler writers, and CPU architects. Instruction mixes are traditionally generated using software instrumentation, an accurate yet slow method, that is normally limite ...

2018

Denial-of-service resilience in peer-to-peer file sharing systems

Dan Mihai Dumitriu, Willy Zwaenepoel

Peer-to-peer (p2p) file sharing systems are characterized by highly replicated content distributed among nodes with enormous aggregate resources for storage and communication. These properties alone are not sufficient, however, to render p2p networks immun ...

2005

Striking a New Balance Between Program Instrumentation and Debugging Time

Willy Zwaenepoel, Ricardo Bianchini, Olivier Crameri

Although they are helpful in many cases, state-of-the-art bug reporting systems may impose excessive overhead on users, leak private information, or provide little help to the developer in locating the problem. In this paper, we explore a new approach to b ...

Acm Order Department, P O Box 64145, Baltimore, Md 21264 Usa2011

Iterative Adaptation for Mobile Clients Using Existing APIs

Willy Zwaenepoel

Iterative Adaptation is a novel approach to adaptation for resource-limited mobile and wireless environments that supports powerful application-specific adaptations without requiring modifications to the application's source code. Common productivity appli ...

2005

HadoopToSQL: a MapReduce Query Optimizer

Willy Zwaenepoel, Christopher Ming-Yee Iu

Map Reduce is a cost-effective way to achieve scalable performance for many log-processing workloads. These workloads typically process their entire dataset. Map Reduce can be inefficient, however, when handling business-oriented workloads, especially when ...

ACM2010

Scrub: Online TroubleShooting for Large Mission-Critical Applications

Willy Zwaenepoel

Scrub is a troubleshooting tool for distributed applications that operate under strict SLOs common in production environments. It allows users to formulate queries on events occurring during execution in order to assess the correctness of the application’s ...

2018

The Battle of the Schedulers: FreeBSD ULE vs. Linux CFS

Sébastien Chevalley, Justinien Gérard Alain Bouron, Willy Zwaenepoel, Baptiste Joseph Eustache Lepers

This paper analyzes the impact on application performance of the design and implementation choices made in two widely used open-source schedulers: ULE, the default FreeBSD scheduler, and CFS, the default Linux scheduler. We compare ULE and CFS in otherwise ...

USENIX ASSOC2018

Hailstorm: Disaggregated Compute and Storage for Distributed LSM-based Databases

Willy Zwaenepoel, Laurent Bindschaedler

Distributed LSM-based databases face throughput and latency issues due to load imbalance across instances and interference from background tasks such as flushing, compaction, and data migration. Hailstorm addresses these problems by deploying the database ...

ACM2020

Optimistic Causal Consistency for Geo-Replicated Key-Value Stores

Willy Zwaenepoel, Diego Didona, Kristina Spirovska

In this paper we present a new approach to implementing causal consistency in geo-replicated data stores, which we call Optimistic Causal Consistency (OCC). The optimism in our approach lies in that updates from a remote data center are immediately made vi ...

Ieee Computer Soc2017

The Fake News Vaccine

Rachid Guerraoui, Willy Zwaenepoel, Anne-Marie Kermarrec, Alexandre David Olivier Maurer, Matej Pavlovic, Oana Maria Balmau

While spreading fake news is an old phenomenon, today social media enables misinformation to instantaneously reach millions of people. Content-based approaches to detect fake news, typically based on automatic text checking, are limited. It is indeed diffi ...

2019

Kairos: Preemptive Data Center Scheduling Without Runtime Estimates

Willy Zwaenepoel, Diego Didona, Florin Dinu, Pamela Isabel Delgado Borda

The vast majority of data center schedulers use task runtime estimates to improve the quality of their scheduling decisions. Knowledge about runtimes allows the schedulers, among other things, to achieve better load balance and to avoid head-of-line blocki ...

2018

Orbe: Scalable Causal Consistency Using Dependency Matrices and Physical Clocks

Willy Zwaenepoel, Sameh Mohamed Elnikety, Jiaqing Du, Amitabha Roy

We propose two protocols that provide scalable causal consistency for both partitioned and replicated data stores using dependency matrices (DM) and physical clocks. The DM protocol supports basic read and update operations and uses two-dimensional depende ...

2013

X-Stream: Edge-centric Graph Processing using Streaming Partitions

Ivo Mihailovic, Willy Zwaenepoel, Amitabha Roy

X-Stream is a system for processing both in-memory and out-of-core graphs on a single shared-memory machine. While retaining the scatter-gather programming model with state stored in the vertices, X-Stream is novel in (i) using an edge-centric rather than ...

ACM2013

Performance Profiling in a Virtualized Environment

Willy Zwaenepoel, Jiaqing Du

Virtualization is a key enabling technology for cloud computing. Many applications deployed in a cloud run in virtual machines. However, profilers based on CPU performance counters do not work well in a virtualized environment. In this paper, we explore th ...

2010