About

Orran Krieger is a Professor at the Department of Electrical and Computer Engineering at Boston University, where he is also an affiliated faculty member in the Department of Computer Science. He is the lead on the Massachusetts Open Cloud and the Founding Director of the Cloud Computing Initiative (CCI) at BU. Additionally, he is a Resident Fellow of the Hariri Institute for Computing and Computational Science & Engineering. Orran Krieger completed his PhD and MASc in Electrical Engineering at the University of Toronto. Prior to his current roles, he spent five years at VMware, working on vCloud, and before that, he was a researcher and manager at IBM T. J. Watson, leading the Advanced Operating System Research Department. His research focuses on cloud computing, data management, and systems engineering, contributing to the development of cloud infrastructure and computational science.

Research topics

• Computer Science
• Operating system
• Computer Security
• Political Science
• Embedded system
• Software engineering
• Distributed computing
• Engineering
• Business
• Database
• Finance
• Parallel computing
• Computer network
• Programming language
• World Wide Web

Selected publications

• Taming and Controlling Performance and Energy Trade-Offs Automatically in Network Applications

  Cloud Computing and Data Science · 2026-03-11

  articleOpen access

  In this paper, we demonstrate that a server running a single latency-sensitive application can be treated as a black box to reduce energy consumption while meeting a Service-Level Agreement (SLA) target. We find that it is possible to identify “sweet spot” settings for packet batching and processing rate control. These settings represent optimal trade-offs between the software stack and hardware. Specifically, they account for both the arrival rate and the composition of requests being served. By testing a few combinations of these settings on the live system, a proof-of concept controller can dynamically find settings that reduce energy consumption while meeting a desired tail latency for the request rate. Our work demonstrates three key findings. First, without software changes, energy savings of up to 60% are achievable across diverse hardware systems by controlling batching and processing rates. Second, specialized research Operating Systems (OSes) can leverage this to achieve a further 40% energy savings over general-purpose OSes. Finally, we show that a controller that is agnostic to the application, system, and hardware, can find energy efficient settings for different request rates while meeting performance objectives.

  PublisherDOI

• Can OS Specialization give new life to old carbon in the cloud?

  2024-09-16 · 1 citations

  articleOpen access

  Is there "fat" (overheads) in cloud computing infrastructure software that can be trimmed? Would doing so help ameliorate the need for frequent hardware refreshes and extend the life of existing hardware? In this paper, we demonstrate that, indeed, there is "fat" that can be trimmed by using specialized OS-based software stacks. Doing so can allow decade-old computers to be used for critical cloud infrastructure services, potentially yielding 3x improvements in efficiency compared to standard software stacks on newer hardware. The implications of these results raise the possibility of exploiting OS optimizations to reduce server hardware obsolescence. Further, it suggests the importance of addressing the key portability challenges of specialized OS stacks.

  PublisherDOI

• Unikernel Linux (UKL)

  2023 · 18 citations

  Senior authorCorresponding
  • Computer Science
  • Operating system
  • Computer Science

  This paper presents Unikernel Linux (UKL), a path toward integrating unikernel optimization techniques in Linux, a general purpose operating system. UKL adds a configuration option to Linux allowing for a single, optimized process to link with the kernel directly, and run at supervisor privilege. This UKL process does not require application source code modification, only a re-link with our, slightly modified, Linux kernel and glibc. Unmodified applications show modest performance gains out of the box, and developers can further optimize applications for more significant gains (e.g. 26% throughput improvement for Redis). UKL retains support for co-running multiple user level processes capable of communicating with the UKL process using standard IPC. UKL preserves Linux's battle-tested codebase, community, and ecosystem of tools, applications, and hardware support. UKL runs both on bare-metal and virtual servers and supports multi-core execution. The changes to the Linux kernel are modest (1250 LOC).

  PublisherDOI

• Beating the I/O bottleneck

  2022-03-28 · 5 citations

  articleOpen access

  With the increasing dominance of SSDs for local storage, today's network mounted virtual disks can no longer offer competitive performance. We propose a Log-Structured Virtual Disk (LSVD) that couples log-structured approaches at both the cache and storage layer to provide a virtual disk on top of S3-like storage. Both cache and backend store are order-preserving, enabling LSVD to provide strong consistency guarantees in case of failure. Our prototype demonstrates that the approach preserves all the advantages of virtual disks, while offering dramatic performance improvements over not only commonly used virtual disks, but the same disks combined with inconsistent (i.e. unsafe) local caching.

  PublisherOA PDFDOI

• Unikernel Linux (UKL)

  arXiv (Cornell University) · 2022-06-01

  preprintOpen accessSenior author

  This paper presents Unikernel Linux (UKL), a path toward integrating unikernel optimization techniques in Linux, a general purpose operating system. UKL adds a configuration option to Linux allowing for a single, optimized process to link with the kernel directly, and run at supervisor privilege. This UKL process does not require application source code modification, only a re-link with our, slightly modified, Linux kernel and glibc. Unmodified applications show modest performance gains out of the box, and developers can further optimize applications for more significant gains (e.g. 26% throughput improvement for Redis). UKL retains support for co-running multiple user level processes capable of communicating with the UKL process using standard IPC. UKL preserves Linux's battle-tested codebase, community, and ecosystem of tools, applications, and hardware support. UKL runs both on bare-metal and virtual servers and supports multi-core execution. The changes to the Linux kernel are modest (1250 LOC).

  PublisherOA PDFDOI

• A Closer Look at Intel Resource Director Technology (RDT)

  2022 · 34 citations

  Senior authorCorresponding
  • Computer Science
  • Computer Science
  • Computer Security

  Unarbitrated contention over shared resources at different levels of the memory hierarchy represents a major source of temporal interference. Hardware manufacturers are increasingly more receptive to issues with temporal interference and are starting to propose concrete solutions to mitigate the problem. Intel Resource Director Technology (RDT) represents one such attempt. Given the wide adoption of Intel platforms, RDT features can be an invaluable asset for the consolidation of real-time systems on complex multi- and many-core machines.

  PublisherDOI

• Slowing Down for Performance and Energy: An OS-Centric Study in Network Driven Workloads

  arXiv (Cornell University) · 2021-12-13

  preprintOpen access

  This paper studies three fundamental aspects of an OS that impact the performance and energy efficiency of network processing: 1) batching, 2) processor energy settings, and 3) the logic and instructions of the OS networking paths. A network device's interrupt delay feature is used to induce batching and processor frequency is manipulated to control the speed of instruction execution. A baremetal library OS is used to explore OS path specialization. This study shows how careful use of batching and interrupt delay results in 2X energy and performance improvements across different workloads. Surprisingly, we find polling can be made energy efficient and can result in gains up to 11X over baseline Linux. We developed a methodology and a set of tools to collect system data in order to understand how energy is impacted at a fine-grained granularity. This paper identifies a number of other novel findings that have implications in OS design for networked applications and suggests a path forward to consider energy as a focal point of systems research.

  PublisherOA PDFDOI

• The Open Cloud Testbed (OCT): A Platform for Research into new Cloud Technologies

  2021 · 18 citations

  • Computer Science
  • Computer Science
  • Operating system

  The NSF-funded Open Cloud Testbed (OCT) project is building and supporting a testbed for research and experimentation into new cloud platforms – the underlying software which provides cloud services to applications. Testbeds such as OCT are critical for enabling research into new cloud technologies – research that requires experiments which potentially change the operation of the cloud itself.This paper gives an overview of the Open Cloud Testbed, including an overview on the existing components OCT is based on and the description of new infrastructure and software extension. In addition, we present several use cases of OCT, including a description of FPGA-based research enabled by newly-deployed resources.

  PublisherDOI

• Security in a Cloud Bazaar

  2021-11-05

  article1st authorCorresponding

  While cloud computing is transforming society, today's public clouds are black boxes, implemented and operated by a single provider that makes all business and technology decisions. In 2013 we launched the Mass Open Cloud (MOC) with the vision of creating a production cloud that would enable innovation by a broad industry and research community. This open cloud has become a laboratory for cloud research and innovation, resulting in hundreds of publications, contributions to open source software, and collaborations between researchers, open source developers, and production operations staff. Recently we launched the Open Research Cloud Initiative (ORCI) to provide a framework to coordinate the bazaar of interrelated projects and initiatives that have evolved since 2013, including the Red Hat [email protected], Open Cloud Testbed (OCT), New England Research Cloud (NERC), Northeast Storage Exchange (NESE), Operate First, and OpenInfra Labs.

  PublisherDOI

• A Community Cache with Complete Information

  2021-01-01 · 2 citations

  article
  Publisher

Recent grants

• EAGER: Holistic Security for Cloud Computing: Architecture for Modular System and Network Design

  NSF · $300k · 2013–2016

Frequent coauthors

• Jonathan Appavoo

  34 shared

• Michael Stumm

  University of Toronto

  23 shared

• Peter Desnoyers

  Northeastern University

  20 shared

• Robert W. Wisniewski

  18 shared

• Azer Bestavros

  17 shared

• Hilarie Orman

  16 shared

• Mirco Musolesi

  16 shared

• Dilma Da Silva

  16 shared

Labs

• Data Mining & Data ManagementPI

Education

• Ph.D.

  University of Toronto

• Other

  University of Toronto