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Publications (240)
Hardware specialization is becoming a key enabler of energyefficient performance. Future systems will be increasingly heterogeneous, integrating multiple specialized and programmable accelerators, each with different memory demands. Traditionally, communication between accelerators has been inefficient, typically orchestrated through explicit DMA t...
As GPUs have become more programmable, their performance and energy benefits have made them increasingly popular. However, while GPU compute units continue to improve in performance, on-chip memories lag behind and data accesses are becoming increasingly expensive in performance and energy. Emerging GPU coherence protocols can mitigate this bottlen...
As the need for specialization increases and architectures become increasingly domain-specific, it is important for architects to understand the requirements of emerging application domains. Augmented and virtual reality (AR/VR) or extended reality (XR) is one such important domain. This paper presents a generic XR workflow and the first benchmark...
As Convolutional Neural Networks (CNNs) are increasingly being employed in safety-critical applications, it is important that they behave reliably in the face of hardware errors. Transient hardware errors may percolate undesirable state during execution, resulting in software-manifested errors which can adversely affect high-level decision making....
This work provides the first study to explore the interaction of update propagation with and without fine-grained synchronization (push vs. pull), emerging coherence protocols (GPU vs. DeNovo coherence), and software-centric consistency models (DRF0, DRF1, and DRFrlx) for graph workloads on emerging integrated GPU-CPU systems with native unified sh...
With the end of conventional CMOS scaling, efficient resiliency solutions are needed to address the increased likelihood of hardware errors. Silent data corruptions (SDCs) are especially harmful because they can create unacceptable output without the user's knowledge. Several resiliency analysis techniques have been proposed to identify SDC-causing...
We propose a parallel program representation for heterogeneous systems, designed to enable performance portability across a wide range of popular parallel hardware, including GPUs, vector instruction sets, multicore CPUs and potentially FPGAs. Our representation, which we call HPVM, is a hierarchical dataflow graph with shared memory and vector ins...
We propose a parallel program representation for heterogeneous systems, designed to enable performance portability across a wide range of popular parallel hardware, including GPUs, vector instruction sets, multicore CPUs and potentially FPGAs. Our representation, which we call HPVM, is a hierarchical dataflow graph with shared memory and vector ins...
An unambiguous and easy-to-understand memory consistency model is crucial for ensuring correct synchronization and guiding future design of heterogeneous systems. In a widely adopted approach, the memory model guarantees sequential consistency (SC) as long as programmers obey certain rules. The popular data-race-free-0 (DRF0) model exemplifies this...
An unambiguous and easy-to-understand memory consistency model is crucial for ensuring correct synchronization and guiding future design of heterogeneous systems. In a widely adopted approach, the memory model guarantees sequential consistency (SC) as long as programmers obey certain rules. The popular data-race-free-0 (DRF0) model exemplifies this...
Programming heterogeneous parallel systems can be extremely complex because a single system may include multiple different parallelism models, instruction sets, and memory hierarchies, and different systems use different combinations of these features. We propose a carefully designed parallel abstraction of heterogeneous hardware -- a hierarchical...
As GPUs have become increasingly general purpose, applications with more general sharing patterns and fine-grained synchronization have started to emerge. Unfortunately, conventional GPU coherence protocols are fairly simplistic, with heavyweight requirements for synchronization accesses. Prior work has tried to resolve these inefficiencies by addi...
Heterogeneous systems employ specialization for energy efficiency. Since data movement is expected to be a dominant consumer of energy, these systems employ specialized memories (e.g., scratchpads and FIFOs) for better efficiency for targeted data. These memory structures, however, tend to exist in local address spaces, incurring significant perfor...
Current shared-memory hardware is complex and inefficient. Prior work on the DeNovo coherence protocol showed that disciplined shared-memory programming models can enable more complexity-, performance-, and energy-efficient hardware than the state-of-the-art MESI protocol. DeNovo, however, severely restricted the synchronization constructs an appli...
While many techniques have been shown to be successful at reducing the amount of on-chip network traffic, no studies have shown how close a combined approach would come to eliminating all unnecessary data traffic, nor have any studies provided insight into where the remaining challenges are. This paper systematically analyzes the traffic inefficien...
Current shared-memory hardware is complex and inefficient. Prior work on the DeNovo coherence protocol showed that disciplined shared-memory programming models can enable more complexity-, performance-, and energy-efficient hardware than the state-of-the-art MESI protocol. DeNovo, however, severely restricted the synchronization constructs an appli...
Cache coherence is an integral part of shared-memory systems but is also widely considered to be one of the most complex parts of such systems. Much prior work has addressed this complexity and the verification techniques to prove the correctness of hardware coherence. Given the new multicore era with increasing number of cores, there is a renewed...
With continued process scaling, the rate of hardware failures in commodity systems is increasing. Because these commodity systems are highly sensitive to cost, traditional solutions that employ heavy redundancy to handle such failures are no longer acceptable owing to their high associated costs.
Detecting such faults by identifying anomalous softw...
As technology scales, the hardware reliability challenge affects a broad computing market, rendering traditional redundancy based solutions too expensive. Software anomaly based hardware error detection has emerged as a low cost reliability solution, but suffers from Silent Data Corruptions (SDCs). It is crucial to accurately evaluate SDC rates and...
As technology scales, the hardware reliability challenge affects a broad computing market, rendering traditional redundancy based solutions too expensive. Software anomaly based hardware error detection has emerged as a low cost reliability solution, but suffers from Silent Data Corruptions (SDCs). It is crucial to accurately evaluate SDC rates and...
Recent work has shown that disciplined shared-memory programming models that provide deterministic-by-default semantics can simplify both parallel software and hardware. Specifically, the DeNovo hardware system has shown that the software guarantees of such models (e.g., data-race-freedom and explicit side-effects) can enable simpler, higher perfor...
Future microprocessors need low-cost solutions for reliable operation in the presence of failure-prone devices. A promising approach is to detect hardware faults by deploying low-cost software-level symptom monitors. However, there remains a nonnegligible risk that several faults might escape these detectors to produce silent data corruptions (SDCs...
Recent work has shown that disciplined shared-memory programming models that provide deterministic-by-default semantics can simplify both parallel software and hardware. Specifically, the DeNovo hardware system has shown that the software guarantees of such models (e.g., data-race-freedom and explicit side-effects) can enable simpler, higher perfor...
We present here a report produced by a workshop on ‘Addressing failures in exascale computing’ held in Park City, Utah, 4–11 August 2012. The charter of this workshop was to establish a common taxonomy about resilience across all the levels in a computing system, discuss existing knowledge on resilience across the various hardware and software laye...
Recent work has shown that disciplined shared-memory programming models that provide deterministic-by-default semantics can simplify both parallel software and hardware. Specifically, the DeNovo hardware system has shown that the software guarantees of such models (e.g., data-race-freedom and explicit side-effects) can enable simpler, higher perfor...
Developing software applications for emerging and future heterogeneous systems with diverse combinations of hardware is significantly harder than for homogeneous multicore systems. In this paper, we identify three root causes that underlie the programming challenges: (1) diverse parallelism models; (2) diverse memory architectures; and (3) diverse...
With technology scaling, transient faults are becoming an increasing threat to hardware reliability. Commodity systems must be made resilient to these in-field faults through very low-cost resiliency solutions. Software-level symptom detection techniques have emerged as promising low-cost and effective solutions. While the current user-visible Sile...
Future microprocessors need low-cost solutions for reliable operation in the presence of failure-prone devices. A promising approach is to detect hardware faults by deploying low-cost monitors of software-level symptoms of such faults. Recently, researchers have shown these mechanisms work well, but there remains a non-negligible risk that several...
Future microprocessors need low-cost solutions for reliable operation in the presence of failure-prone devices. A promising approach is to detect hardware faults by deploying low-cost monitors of software-level symptoms of such faults. Recently, researchers have shown these mechanisms work well, but there remains a non-negligible risk that several...
Future microprocessors need low-cost solutions for reliable operation in the presence of failure-prone devices. A promising approach is to detect hardware faults by deploying low-cost monitors of software-level symptoms of such faults. Recently, researchers have shown these mechanisms work well, but there remains a non-negligible risk that several...
Current technology scaling is leading to increasingly fragile components, making hardware reliability a primary design consideration. Recently researchers have proposed low-cost reliability solutions that detect hardware faults through software-level symptom monitoring. SWAT (SoftWare Anomaly Treatment), one such solution, demonstrated with microar...
Threads are multiple programs running at the same time while sharing variables. Shared variables are either the core strength of threads or the root of their evil, depending on a user's perspective. They allow threads to communicate easily and quickly, while making it possible for threads to get in each other's way. Experts are confused about the r...
For parallelism to become tractable for mass programmers, shared-memory languages and environments must evolve to enforce disciplined practices that ban "wild shared-memory behaviors;'' e.g., unstructured parallelism, arbitrary data races, and ubiquitous non-determinism. This software evolution is a rare opportunity for hardware designers to rethin...
The era of parallel computing for the masses is here, but writing correct parallel programs remains difficult. For many domains, shared-memory remains an attractive programming model. The memory model, which specifies the meaning of shared variables, is at the heart of this programming model. Unfortunately, it has involved a tradeoff between progra...
The huge investment in the design and production of multicore processors may be put at risk because the emerging highly miniaturized but unreliable fabrication technologies will impose significant barriers to the life-long reliable operation of future chips. Extremely complex, massively parallel, multi-core processor chips fabricated in these techn...
A number of deterministic parallel programming models with strong safety guarantees are emerging, but similar support for nondeterministic algorithms, such as branch and bound search, remains an open question. We present a language together with a type and effect system that supports nondeterministic computations with a deterministic-by-default gua...
