Research Days US 2020

Consolidating multiple applications on the same multi-core platform while preserving their performance is of the utmost importance in real-time systems. A similar problem has emerged in cloud computing systems. Meeting SLAs requires isolating the performance of primary workloads from co-located noisy neighbors. Lack of performance isolation arises due to contention over shared memory resources, such as last-level cache space, main memory bandwidth, and DRAM banks. Hardware vendors like Intel have started introducing techniques like Resource Director Technology (RDT) to manage shared memory resources. In the context of RDT, a promising feature is Memory Bandwidth Allocation (MBA).

In this presentation, we study whether MBA is capable of providing strong isolation via main memory bandwidth management. In doing so, we make a series of surprising discoveries. Come to the presentation to have a look at these and see joint management of main memory and LLC bandwidth by combining MBA and budget-based regulation.

Unikernels are small, lightweight, single address space operating systems with the kernel included as a library within the application. Because unikernels run a single application, there is no sharing or competition for resources among different applications, improving performance and security. Unikernels have thus far seen limited production deployment. This project aims to turn the Linux kernel into a unikernel with the following characteristics: 1) easily compiled for any application, 2) uses battle-tested, production Linux and glibc code, 3) allows the entire upstream Linux developer community to maintain and develop the code, and 4) provides applications normally running vanilla Linux to benefit from unikernel performance and security advantages. The paper Unikernels: The Next Stage of Linux’s Dominance was presented at HotOS XVII, The 17th Workshop on Hot Topics in Operating Systems, 2019.

While FPGAs have been traditionally considered hard to program, recently there have been efforts aimed to allow the use of high-level programming models and libraries intended for multi-core CPUs and GPUs to program FPGAs. For example, both Intel and Xilinx are now providing toolchains to deploy OpenCL code onto FPGA. However, because the nature of the parallelism offered by GPU and FPGA devices is fundamentally different, OpenCL code optimized for GPU can prove very inefficient on FPGA, in terms of both performance and hardware resource utilization.

We explored this problem on finite automata traversal. In particular, we consider an OpenCL NFA traversal kernel optimized for GPU but exhibiting FPGA-friendly characteristics, namely: limited memory requirements, lack of synchronization, and SIMD execution. We explore a set of structural code changes, custom, and best-practice optimizations to retarget this code to FPGA. We showcase the effect of these optimizations on an Intel Stratix V FPGA board using various NFA topologies from different application domains. Our evaluation shows that, while the resource requirements of the original code exceed the capacity of the FPGA in use, our optimizations lead to significant resource savings and allow the transformed code to fit the FPGA for all considered NFA topologies. In addition, our optimizations lead to speedups up to 4x over an already optimized code-variant aimed to fit the NFA traversal kernel on FPGA. Some of the proposed optimizations can be generalized for other applications and introduced in OpenCL-to-FPGA compiler.

Mostafa Eghbali Zarch, a PhD student at NCSU also working under the supervision of Dr. Michela Becchi, contributed to this work. Zarch's research is focused on the exploration of different optimizations and scheduling methods on high-level synthesis tools for FPGAs, specifically OpenCL to FPGA SDKs.

Synthesis and simulation of hardware design can take hours before results are available, even for small changes. In contrast, software development embraced live programming to boost productivity. This article proposes LiveHD, an open-source incremental framework for hardware synthesis and simulation that provides feedback within seconds. Three principles for incremental design automation are presented. LiveHD uses a unified VLSI data model, LGraph, to support the implementation of incremental principles for synthesis and simulation. LiveHD also employs a tree-like high-level intermediate representation to interface modern hardware description languages. We present early results comparing with commercial and open source tools. LiveHD can provide feedback for synthesis, placement and routing in < 30s for most changes tested with negligible QoR impact. For the incremental simulation, LiveHD is capable of completing any simulation cycle in under 2s for a 256 RISC-V core design.

When big data intersects with highly sensitive data, both opportunity to society and risks abound. Traditional approaches for sharing sensitive data are known to be ineffective in protecting privacy. Differential Privacy, deriving from roots in cryptography, is a strong mathematical criterion for privacy preservation that also allows for rich statistical analysis of sensitive data. Differentially private algorithms are constructed by carefully introducing “random noise” into statistical analyses so as to obscure the effect of each individual data subject.    OpenDP is an open-source project for the differential privacy community to develop general-purpose, vetted, usable, and scalable tools for differential privacy, which users can simply, robustly and confidently deploy. 

Dataverse is an open source web application to share, preserve, cite, explore, and analyze research data. It facilitates making data available to others, and allows you to replicate others' work more easily. Researchers, journals, data authors, publishers, data distributors, and affiliated institutions all receive academic credit and web visibility.  A Dataverse repository is the software installation, which then hosts multiple virtual archives called Dataverses. Each dataverse contains datasets, and each dataset contains descriptive metadata and data files (including documentation and code that accompany the data).

This session examines ongoing efforts to realize a combined use case for these projects that will offer academic researchers privacy-preserving access to sensitive data. This would allow both novel secondary reuse and replication access to data that otherwise is commonly locked away in archives.  The session will also explore the potential impact of this work outside the academic world.

Consider an agency holding a large database of sensitive personal information—say,  medical records, census survey answers, web searches, or genetic data. The agency would like to discover and publicly release global characteristics of the data while protecting the privacy of individuals' records. I will present differential privacy, a rigorous definition of privacy for such settings that is now widely studied, and increasingly used to analyze and design deployed systems. I'll explain how this line of research might help share information about a data center's operations in ways that protect clients' interests, and discuss a few of the challenges that arise.

This talk focuses on our experience building and deploying various iterations of a web-based secure Multi-Party Computation (MPC) platform. Our experience demonstrates that secure computations can add value to questions of social good when otherwise constrained by legal, ethical, or privacy restrictions, and that it is feasible to deploy MPC solutions today.