Josh Fried

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I am an incoming Assistant Professor in the Department of Computer and Information Science at the University of Pennsylvania, starting in Fall 2026. I recently completed my PhD at MIT CSAIL, where I was advised by Adam Belay. My undergraduate degree is also from Penn, where I researched applied cryptography and systems security with Nadia Heninger.

This year, I’m a Software Engineer at Google working on datacenter networking.

My research aims to improve datacenter efficiency by designing innovative operating systems and resource management techniques that leverage kernel bypass, microsecond-scale scheduling, and system-level optimizations to achieve significant performance and efficiency gains. Much of this work culminated in Junction, which brings the efficiencies of these designs to unmodified applications.

Research Group

At Penn, I will be building a research group focused on next-generation datacenter software systems. We will study how modern hardware and software interact, and develop new abstractions, scheduling models, and control mechanisms that improve performance, efficiency, and adaptability at scale.

I am looking for PhD students who are passionate about building and understanding real systems, and who are excited to explore new ideas that push the boundaries of datacenter computing. If you’re interested in joining my group, please apply here.

Publications

  1. Oasis: Pooling PCIe Devices Over CXL to Boost Utilization
    Yuhong Zhong, Daniel S. Berger, Pantea Zardoshti, Enrique Saurez, Jacob Nelson, Dan R. K. Ports, Antonis Psistakis, Joshua Fried, and Asaf Cidon
    In SOSP 2025
  2. ML-native Dataplane Operating Systems
    Inho Choi, Anand Bonde, Jing Liu, Joshua Fried, Irene Zhang, and Jialin Li
    In APSys 2025
  3. Beware, PCIe Switches! CXL Pools Are Out to Get You
    Yuhong Zhong, Daniel Berger, Pantea Zardoshti, Enrique Saurez, Jacob Nelson, Antonis Psistakis, Joshua Fried, and Asaf Cidon
    In HotOS 2025
  4. Making Kernel Bypass Practical for the Cloud with Junction
    Joshua Fried, Gohar Irfan Chaudhry, Enrique Saurez, Esha Choukse, Íñigo Goiri, Sameh Elnikety, Rodrigo Fonseca, and Adam Belay
    In NSDI 2024
  5. Capybara: muSecond-Scale Live TCP Migration
    Inho Choi, Nimish Wadekar, Raj Joshi, Joshua Fried, Dan R.K. Ports, Irene Zhang, and Jialin Li
    In APSys 2023
  6. Efficient Strong Scaling Through Burst Parallel Training
    Seo Jin Park, Joshua Fried, Sunghyun Kim, Mohammad Alizadeh, and Adam Belay
    In MLSys 2022
  7. When Idling is Ideal: Optimizing Tail-Latency for Heavy-Tailed Datacenter Workloads with Persephone
    Henri Maxime Demoulin, Joshua Fried, Isaac Pedisich, Marios Kogias, Boon Thau Loo, Linh Thi Xuan Phan, and Irene Zhang
    In SOSP 2021
  8. Caladan: Mitigating Interference at Microsecond Timescales
    Joshua Fried, Zain Ruan, Amy Ousterhout, and Adam Belay
    In OSDI 2020
  9. Overload Control for microsecond-scale RPCs with Breakwater
    Inho Cho, Ahmed Saeed, Joshua Fried, Seo Jin Park, Mohammad Alizadeh, and Adam Belay
    In OSDI 2020
  10. Shenango: Achieving High CPU Efficiency for Latency-sensitive Datacenter Workloads
    Amy Ousterhout, Joshua Fried, Jonathan Behrens, Adam Belay, and Hari Balakrishnan
    In NSDI 2019
  11. A kilobit hidden SNFS discrete logarithm computation
    Joshua Fried, Pierrick Gaudry, Nadia Heninger, and Emmanuel Thome
    In Eurocrypt 2017
  12. Measuring small subgroup attacks against Diffie-Hellman
    Luke Valenta, David Adrian, Antonio Sanso, Shaanan Cohney, Joshua Fried, Marcella Hastings, J. Alex Halderman, and Nadia Heninger
    In NDSS 2017
  13. Weak keys remain widespread in network devices
    Marcella Hastings, Joshua Fried, and Nadia Heninger
    In ACM IMC 2016
  14. A Systematic Analysis of the Juniper Dual EC Incident
    Stephen Checkoway, Jacob Maskiewicz, Christina Garman, Joshua Fried, Shaanan Cohney, Matthew Green, Nadia Heninger, Ralf-Philipp Weinmann, Eric Rescorla, and Hovav Shacham
    In ACM CCS 2016
  15. Factoring as a Service
    Luke Valenta, Shaanan Cohney, Alex Liao, Joshua Fried, Satya Bodduluri, and Nadia Heninger
    In Financial Cryptography 2016