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Creators/Authors contains: "Zaharia, Matei"

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  1. ; ; ; ; ; ; ; ; ( , NeurIPS Data-Centric AI Workshop 2021)
    A common problem practitioners face is to select rare events in a large dataset. Unfortunately, standard techniques ranging from pre-trained models to active learning do not leverage proximity structure present in many datasets and can lead to worse-than-random results. To address this, we propose EZMODE, an algorithm for iterative selection of rare events in large, unlabeled datasets. EZMODE leverages active learning to iteratively train classifiers, but chooses the easiest positive examples to label in contrast to standard uncertainty techniques. EZMODE also leverages proximity structure (e.g., temporal sampling) to find difficult positive examples. We show that EZMODE can outperform baselines bymore »up to 130× on a novel, real-world, 9,000 GB video dataset.« less
    Free, publicly-accessible full text available December 14, 2022
  2. ; ; ; ; ( , OSDI 2020)
    Specialized accelerators such as GPUs, TPUs, FPGAs, and custom ASICs have been increasingly deployed to train deep learning models. These accelerators exhibit heterogeneous performance behavior across model architectures. Existing schedulers for clusters of accelerators, which are used to arbitrate these expensive training resources across many users, have shown how to optimize for various multi-job, multiuser objectives, like fairness and makespan. Unfortunately, existing schedulers largely do not consider performance heterogeneity. In this paper, we propose Gavel, a heterogeneity-aware scheduler that systematically generalizes a wide range of existing scheduling policies. Gavel expresses these policies as optimization problems and then systematically transforms thesemore »problems into heterogeneity-aware versions using an abstraction we call effective throughput. Gavel then uses a round-based scheduling mechanism to ensure jobs receive their ideal allocation given the target scheduling policy. Gavel’s heterogeneity-aware policies allow a heterogeneous cluster to sustain higher input load, and improve end objectives such as makespan and average job completion time by 1.4⇥ and 3.5⇥ compared to heterogeneity-agnostic policies.« less
    Accepted Manuscript Full Text Available
  3. ; ( , SPAA 2020)
    We consider the problem of finding lower bounds on the I/O complexity of arbitrary computations in a two level memory hierarchy. Executions of complex computations can be formalized as an evaluation order over the underlying computation graph. However, prior methods for finding I/O lower bounds leverage the graph structures for specific problems (e.g matrix multiplication) which cannot be applied to arbitrary graphs. In this paper, we first present a novel method to bound the I/O of any computation graph using the first few eigenvalues of the graph’s Laplacian. We further extend this bound to the parallel setting. This spectral boundmore »is not only efficiently computable by power iteration, but can also be computed in closed form for graphs with known spectra. We apply our spectral method to compute closed-form analytical bounds on two computation graphs (the Bellman-Held-Karp algorithm for the traveling salesman problem and the Fast Fourier Transform), as well as provide a probabilistic bound for random Erdős Rényi graphs. We empirically validate our bound on four computation graphs, and find that our method provides tighter bounds than current empirical methods and behaves similarly to previously published I/O bounds.« less
    Full Text Available 
  4. ; ; ; ; ( , VLDB DISPA Workshop 2020)
    Cloud providers offer instances with similar compute capabilities (for example, instances with different generations of GPUs like K80s, P100s, V100s) across many regions, availability zones, and on-demand and spot markets, with prices governed independently by individual supplies and demands. In this paper, using machine learning model training as an example application, we explore the potential cost reductions possible by leveraging this cross-cloud instance market. We present quantitative results on how the prices of cloud instances change with time, and how total costs can be decreased by considering this dynamic pricing market. Our preliminary experiments show that a) the optimal instancemore »choice for a model is dependent on both the objective (e.g., cost, time, or combination) and the model’s performance characteristics, b) the cost of moving training jobs between instances is cheap, c) jobs do not need to be preempted more frequently than once a day to leverage the benefits from spot instance price variations, and d) the cost of training a model can be decreased by as much as 3.5× compared to a static policy. We also look at contexts where users specify higherlevel objectives over collections of jobs, show examples of policies for these contexts, and discuss additional challenges involved in making these cost reductions viable.« less
    Accepted Manuscript Full Text Available
  5. ; ; ; ( , USENIX ATC 2020)
    We present POSH, a framework that accelerates shell applications with I/O-heavy components, such as data analytics with command-line utilities. Remote storage such as networked filesystems can severely limit the performance of these applications: data makes a round trip over the network for relatively little computation at the client. Reducing the data movement by moving the code to the data can improve performance. POSH automatically optimizes unmodified I/O-intensive shell applications running over remote storage by offloading the I/O-intensive portions to proxy servers closer to the data. A proxy can run directly on a storage server, or on a machine closer tomore »the storage layer than the client. POSH intercepts shell pipelines and uses metadata called annotations to decide where to run each command within the pipeline. We address three principal challenges that arise: an annotation language that allows POSH to understand which files a command will access, a scheduling algorithm that places commands to minimize data movement, and a system runtime to execute a distributed schedule but retain local semantics. We benchmark POSH on real shell pipelines such as image processing, network security analysis, log analysis, distributed system debugging, and git. We find that POSH provides speedups ranging from 1.6× to 15× compared to NFS, without requiring any modifications to the applications.« less
    Accepted Manuscript Full Text Available
  6. ; ; ; ( , USENIX ATC 2020)
    As specialized hardware accelerators such as GPUs become increasingly popular, developers are looking for ways to target these platforms with high-level APIs. One promising approach is kernel libraries such as PyTorch or cuML, which provide interfaces that mirror CPU-only counterparts such as NumPy or Scikit-Learn. Unfortunately, these libraries are hard to develop and to adopt incrementally: they only support a subset of their CPU equivalents, only work with datasets that fit in device memory, and require developers to reason about data placement and transfers manually. To address these shortcomings, we present a new approach called offload annotations (OAs) that enablesmore »heterogeneous GPU computing in existing workloads with few or no code modifications. An annotator annotates the types and functions in a CPU library with equivalent kernel library functions and provides an offloading API to specify how the inputs and outputs of the function can be partitioned into chunks that fit in device memory and transferred between devices. A runtime then maps existing CPU functions to equivalent GPU kernels and schedules execution, data transfers and paging. In data science workloads using CPU libraries such as NumPy and Pandas, OAs enable speedups of up to 1200⇥ and a median speedup of 6.3⇥ by transparently offloading functions to a GPU using existing kernel libraries. In many cases, OAs match the performance of handwritten heterogeneous implementations. Finally, OAs can automatically page data in these workloads to scale to datasets larger than GPU memory, which would need to be done manually with most current GPU libraries.« less
    Accepted Manuscript Full Text Available
  7. ; ; ( , ASPLOS 2020)
    We present Fleet, a framework that offers a massively parallel streaming model for FPGAs and is effective in a number of domains well-suited for FPGA acceleration, including parsing, compression, and machine learning. Fleet requires the user to specify RTL for a processing unit that serially processes every input token in a stream, a far simpler task than writing a parallel processing unit. It then takes the user’s processing unit and generates a hardware design with many copies of the unit as well as memory controllers to feed the units with separate streams and drain their outputs. Fleet includes a Chisel-basedmore »processing unit language. The language maintains Chisel’s low-level performance control while adding a few productivity features, including automatic handling of ready-valid signaling and a native and automatically pipelined BRAM type. We evaluate Fleet on six different applications, including JSON parsing and integer compression, fitting hundreds of Fleet processing units on the Amazon F1 FPGA and outperforming CPU implementations by over 400× and GPU implementations by over 9× in performance per watt while requiring a similar number of lines of code.« less
    Full Text Available 
  8. ; ; ; ; ; ( , MLSys 2020)
    Systems for ML inference are widely deployed today, but they typically optimize ML inference workloads using techniques designed for conventional data serving workloads and miss critical opportunities to leverage the statistical nature of ML. In this paper, we present WILLUMP, an optimizer for ML inference that introduces two statistically-motivated optimizations targeting ML applications whose performance bottleneck is feature computation. First, WILLUMP automatically cascades feature computation for classification queries: WILLUMP classifies most data inputs using only high-value, low-cost features selected through empirical observations of ML model performance, improving query performance by up to 5× without statistically significant accuracy loss. Second, WILLUMPmore »accurately approximates ML top-K queries, discarding low-scoring inputs with an automatically constructed approximate model and then ranking the remainder with a more powerful model, improving query performance by up to 10× with minimal accuracy loss. WILLUMP automatically tunes these optimizations’ parameters to maximize query performance while meeting an accuracy target. Moreover, WILLUMP complements these statistical optimizations with compiler optimizations to automatically generate fast inference code for ML applications. We show that WILLUMP improves the end-to-end performance of real-world ML inference pipelines curated from major data science competitions by up to 16× without statistically significant loss of accuracy.« less
    Accepted Manuscript Full Text Available
  9. ; ( , SOSP)
    Data movement between main memory and the CPU is a major bottleneck in parallel data-intensive applications. In response, researchers have proposed using compilers and intermediate representations (IRs) that apply optimizations such as loop fusion under existing high-level APIs such as NumPy and TensorFlow. Even though these techniques generally do not require changes to user applications, they require intrusive changes to the library itself: often, library developers must rewrite each function using a new IR. In this paper, we propose a new technique called split annotations (SAs) that enables key data movement optimizations over unmodified library functions. SAs only require developersmore »to annotate functions and implement an API that specifies how to partition data in the library. The annotation and API describe how to enable cross-function data pipelining and parallelization, while respecting each function's correctness constraints. We implement a parallel runtime for SAs in a system called Mozart. We show that Mozart can accelerate workloads in libraries such as Intel MKL and Pandas by up to 15x, with no library modifications. Mozart also provides performance gains competitive with solutions that require rewriting libraries, and can sometimes outperform these systems by up to 2x by leveraging existing hand-optimized code.« less
    Full Text Available 
  10. ; ; ; ; ; ( , SOSP)
    Existing deep neural network (DNN) frameworks optimize the computation graph of a DNN by applying graph transformations manually designed by human experts. This approach misses possible graph optimizations and is difficult to scale, as new DNN operators are introduced on a regular basis. We propose TASO, the first DNN computation graph optimizer that automatically generates graph substitutions. TASO takes as input a list of operator specifications and generates candidate substitutions using the given operators as basic building blocks. All generated substitutions are formally verified against the operator specifications using an automated theorem prover. To optimize a given DNN computation graph,more »TASO performs a cost-based backtracking search, applying the substitutions to find an optimized graph, which can be directly used by existing DNN frameworks. Our evaluation on five real-world DNN architectures shows that TASO outperforms existing DNN frameworks by up to 2.8X, while requiring significantly less human effort. For example, TensorFlow currently contains approximately 53,000 lines of manual optimization rules, while the operator specifications needed by TASO are only 1,400 lines of code.« less
    Full Text Available