4,598 research outputs found
The Virtual Block Interface: A Flexible Alternative to the Conventional Virtual Memory Framework
Computers continue to diversify with respect to system designs, emerging
memory technologies, and application memory demands. Unfortunately, continually
adapting the conventional virtual memory framework to each possible system
configuration is challenging, and often results in performance loss or requires
non-trivial workarounds. To address these challenges, we propose a new virtual
memory framework, the Virtual Block Interface (VBI). We design VBI based on the
key idea that delegating memory management duties to hardware can reduce the
overheads and software complexity associated with virtual memory. VBI
introduces a set of variable-sized virtual blocks (VBs) to applications. Each
VB is a contiguous region of the globally-visible VBI address space, and an
application can allocate each semantically meaningful unit of information
(e.g., a data structure) in a separate VB. VBI decouples access protection from
memory allocation and address translation. While the OS controls which programs
have access to which VBs, dedicated hardware in the memory controller manages
the physical memory allocation and address translation of the VBs. This
approach enables several architectural optimizations to (1) efficiently and
flexibly cater to different and increasingly diverse system configurations, and
(2) eliminate key inefficiencies of conventional virtual memory. We demonstrate
the benefits of VBI with two important use cases: (1) reducing the overheads of
address translation (for both native execution and virtual machine
environments), as VBI reduces the number of translation requests and associated
memory accesses; and (2) two heterogeneous main memory architectures, where VBI
increases the effectiveness of managing fast memory regions. For both cases,
VBI significanttly improves performance over conventional virtual memory
CHOP: adaptive filter-based DRAM caching for CMP server platforms
Journal ArticleAs manycore architectures enable a large number of cores on the die, a key challenge that emerges is the availability of memory bandwidth with conventional DRAM solutions. To address this challenge, integration of large DRAM caches that provide as much as 5Ă— higher bandwidth and as low as 1/3rd of the latency (as compared to conventional DRAM) is very promising. However, organizing and implementing a large DRAM cache is challenging because of two primary tradeoffs: (a) DRAM caches at cache line granularity require too large an on-chip tag area that makes it undesirable and (b) DRAM caches with larger page granularity require too much bandwidth because the miss rate does not reduce enough to overcome the bandwidth increase. In this paper, we propose CHOP (Caching HOt Pages) in DRAM caches to address these challenges. We study several filter-based DRAM caching techniques: (a) a filter cache (CHOP-FC) that profiles pages and determines the hot subset of pages to allocate into the DRAM cache, (b) a memory-based filter cache (CHOPMFC) that spills and fills filter state to improve the accuracy and reduce the size of the filter cache and (c) an adaptive DRAM caching technique (CHOP-AFC) to determine when the filter cache should be enabled and disabled for DRAM caching. We conduct detailed simulations with server workloads to show that our filter-based DRAM caching techniques achieve the following: (a) on average over 30% performance improvement over previous solutions, (b) several magnitudes lower area overhead in tag space required for cache-line based DRAM caches, (c) significantly lower memory bandwidth consumption as compared to page-granular DRAM caches. Index Terms-DRAM cache; CHOP; adaptive filter; hot page; filter cache
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SoC-Based In-Storage Processing: Bringing Flexibility and Efficiency to Near-Data Processing
Data are among the most valuable assets in the modern world, and they have caused a revolutionary stage in human life. Nowadays, companies make knowledge-based decisions by analyzing a huge volume of data, super-scale data centers are used to process customers’ data to suggest products to them, government services rely on the data people provide to them, and there are many similar cases wherein data are used as an important asset. Data are originally stored in storage systems. To process data, application servers need to fetch the data from storage units, which imposes the cost of moving the data to the system. This cost has a direct relationship to the distance of the processing engines from the data, and this is the key motivation for the emergence of distributed processing platforms such as Hadoop, which bring the process closer to the data.In-storage processing (ISP) pushes the “bring the process to data” paradigm to its ultimate boundaries by utilizing processing engines inside the storage units to process data. The architecture of modern solid-state drives (SSDs) provides a suitable environment for implementing such technology. Thus, this dissertation focuses on SSD architectures that are able to run user applications in-place, which are called computational storage devices (CSDs). In this dissertation, we propose CSD architectures and investigate the benefits of deploying CSDs for running different applications. This research uses a practical approach that includes building fully functional prototypes of the proposed CSD architectures, developing storage systems equipped with the CSDs, and running different benchmarks to investigate the benefits of deploying the CSDs in the systems. This research proposes two different CSD architectures, namely CompStor and Catalina.These are the first CSDs to be equipped with a dedicated ISP engine for running user applications in-place that includes a quad-core ARM Cortex-A53 processor together with FPGA- and application-specific integrated circuit (ASIC) based accelerators. The proposed architectures run a full-fledged operating system inside, which provides a flexible environment for running a wide range of user applications in-place. The system-on-chip (SOC) based architecture of Catalina CSD, together with a software stack developed for seamless deployment of the CSD, makes it a platform for the implementation of different ISP concepts and ideas.To the best of our knowledge, Catalina is the only ISP platform that can be seamlessly deployed in clusters to run distributed applications such as Hadoop MapReduce and message passing interface (MPI) based applications in-place without any modifications to the underlying distributed processing framework. We performed extensive experimental tests using several datasets on both CompStor and Catalina CSDs. The experimental results show up to 2.2x and 4.3x improvements in performance and energy consumption, respectively, for running Hadoop MapReduce benchmarks using Catalina CSDs and up to 5.4x and 8.9x improvements for running 1-, 2-, and 3-dimensional DFT algorithms due to the Neon SIMD engines inside Catalina. Additionally, using FPGA-based accelerators, Catalina CSDs can improve the performance and energy consumption of a highly demanding image similarity search application up to 11x and 7x, respectively
GPUs as Storage System Accelerators
Massively multicore processors, such as Graphics Processing Units (GPUs),
provide, at a comparable price, a one order of magnitude higher peak
performance than traditional CPUs. This drop in the cost of computation, as any
order-of-magnitude drop in the cost per unit of performance for a class of
system components, triggers the opportunity to redesign systems and to explore
new ways to engineer them to recalibrate the cost-to-performance relation. This
project explores the feasibility of harnessing GPUs' computational power to
improve the performance, reliability, or security of distributed storage
systems. In this context, we present the design of a storage system prototype
that uses GPU offloading to accelerate a number of computationally intensive
primitives based on hashing, and introduce techniques to efficiently leverage
the processing power of GPUs. We evaluate the performance of this prototype
under two configurations: as a content addressable storage system that
facilitates online similarity detection between successive versions of the same
file and as a traditional system that uses hashing to preserve data integrity.
Further, we evaluate the impact of offloading to the GPU on competing
applications' performance. Our results show that this technique can bring
tangible performance gains without negatively impacting the performance of
concurrently running applications.Comment: IEEE Transactions on Parallel and Distributed Systems, 201
Functional requirements document for the Earth Observing System Data and Information System (EOSDIS) Scientific Computing Facilities (SCF) of the NASA/MSFC Earth Science and Applications Division, 1992
Five scientists at MSFC/ESAD have EOS SCF investigator status. Each SCF has unique tasks which require the establishment of a computing facility dedicated to accomplishing those tasks. A SCF Working Group was established at ESAD with the charter of defining the computing requirements of the individual SCFs and recommending options for meeting these requirements. The primary goal of the working group was to determine which computing needs can be satisfied using either shared resources or separate but compatible resources, and which needs require unique individual resources. The requirements investigated included CPU-intensive vector and scalar processing, visualization, data storage, connectivity, and I/O peripherals. A review of computer industry directions and a market survey of computing hardware provided information regarding important industry standards and candidate computing platforms. It was determined that the total SCF computing requirements might be most effectively met using a hierarchy consisting of shared and individual resources. This hierarchy is composed of five major system types: (1) a supercomputer class vector processor; (2) a high-end scalar multiprocessor workstation; (3) a file server; (4) a few medium- to high-end visualization workstations; and (5) several low- to medium-range personal graphics workstations. Specific recommendations for meeting the needs of each of these types are presented
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