{"title":"A software-SVM-based transactional memory for multicore accelerator architectures with local memory","authors":"Jun Lee, Sangmin Seo, Jaejin Lee","doi":"10.1145/1854273.1854355","DOIUrl":"https://doi.org/10.1145/1854273.1854355","url":null,"abstract":"We propose a software transactional memory (STM) for heterogeneous multicores with small local memory. The heterogeneous multicore architecture consists of a general-purpose processor element (GPE) and multiple accelerator processor elements (APEs). The GPE is typically backed by a deep, on-chip cache hierarchy and hardware cache coherence. On the other hand, the APEs have small, explicitly addressed local memory that is not coherent with the main memory. Programmers of such multicore architectures suffer from explicit memory management and coherence problems. The STM for such multicores can alleviate the burden of the programmer and transparently handle data transfers at run time. Moreover, it makes the programmer free from controlling locks. Our TM is based on an existing software SVM for the accelerator architecture. The software SVM exploits software-managed caches and coherence protocols between the GPE and APEs. We also propose an optimization technique, called abort prediction, for the TM. It blocks a transaction from running until the chance of potential conflicts is eliminated. We implement the TM system and the optimization technique for a single Cell BE processor and evaluate their effectiveness with six compute-intensive benchmark applications.","PeriodicalId":422461,"journal":{"name":"2010 19th International Conference on Parallel Architectures and Compilation Techniques (PACT)","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2010-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124388534","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Sergey Zhuravlev, S. Blagodurov, Alexandra Fedorova
{"title":"AKULA: A toolset for experimenting and developing thread placement algorithms on multicore systems","authors":"Sergey Zhuravlev, S. Blagodurov, Alexandra Fedorova","doi":"10.1145/1854273.1854307","DOIUrl":"https://doi.org/10.1145/1854273.1854307","url":null,"abstract":"Multicore processors have become commonplace in both desktop and servers. A serious challenge with multicore processors is that cores share on and off chip resources such as caches, memory buses, and memory controllers. Competition for these shared resources between threads running on different cores can result in severe and unpredictable performance degradations. It has been shown in previous work that the OS scheduler can be made shared-resource-aware and can greatly reduce the negative effects of resource contention. The search space of potential scheduling algorithms is huge considering the diversity of available multicore architectures, an almost infinite set of potential workloads, and a variety of conflicting performance goals. We believe the two biggest obstacles to developing new scheduling algorithms are the difficulty of implementation and the duration of testing. We address both of these challenges with our toolset AKULA which we introduce in this paper. AKULA provides an API that allows developers to implement and debug scheduling algorithms easily and quickly without the need to modify the kernel or use system calls. AKULA also provides a rapid evaluation module, based on a novel evaluation technique also introduced in this paper, which allows the created scheduling algorithm to be tested on a wide variety of workloads in just a fraction of the time testing on real hardware would take. AKULA also facilitates running scheduling algorithms created with its API on real machines without the need for additional modifications. We use AKULA to develop and evaluate a variety of different contention-aware scheduling algorithms. We use the rapid evaluation module to test our algorithms on thousands of workloads and assess their scalability to futuristic massively multicore machines.","PeriodicalId":422461,"journal":{"name":"2010 19th International Conference on Parallel Architectures and Compilation Techniques (PACT)","volume":"119 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2010-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121362295","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Towards a science of parallel programming","authors":"K. Pingali","doi":"10.1145/1854273.1854277","DOIUrl":"https://doi.org/10.1145/1854273.1854277","url":null,"abstract":"How do we give parallel programming a more scientific foundation? In this talk, I will discuss the approach we are taking in the Galois project.","PeriodicalId":422461,"journal":{"name":"2010 19th International Conference on Parallel Architectures and Compilation Techniques (PACT)","volume":"28 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2010-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114856104","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
J. Gummaraju, L. Morichetti, Michael Houston, B. Sander, Benedict R. Gaster, Bixia Zheng
{"title":"Twin Peaks: A Software Platform for Heterogeneous Computing on General-Purpose and Graphics Processors","authors":"J. Gummaraju, L. Morichetti, Michael Houston, B. Sander, Benedict R. Gaster, Bixia Zheng","doi":"10.1145/1854273.1854302","DOIUrl":"https://doi.org/10.1145/1854273.1854302","url":null,"abstract":"Modern processors are evolving into hybrid, heterogeneous processors with both CPU and GPU cores used for generalpurpose computation. Several languages such as Brook, CUDA , and more recently OpenCL are being developed to fully harness the potential of these processors. These languages typically involve the control code running on the CPU and the performance-critical, data-parallel kernel code running on the GPUs. In this paper, we present Twin Peaks, a software platform for heterogeneous computing that executes code originally targeted for GPUs effi ciently on CPUs as well. This permits a more balanced execution between the CPU and GPU, and enables portability of code between these architectures and to CPU-only environments. We propose several techniques in the runtime system to efficiently utilize the caches and functional units present in CPUs. Using OpenCL as a canonical language for heterogeneous computing, and running several experiments on real hardware, we show that our techniques enable GPGPU-style code to execute efficiently on multi core CPUs with minimal runtime overhead. These results also show that for maximum performance, it is beneficial for applications to utilize both CPUs and GPUs as accelerator targets. Categories a nd Subject D escriptors: D.1.3 [Programming Techniques] : Concurrent Programming G eneral Terms: Design , Experimentation, Performance. K eywords: GPGPU, Multicore , OpenCL, Programmability, Runtime.","PeriodicalId":422461,"journal":{"name":"2010 19th International Conference on Parallel Architectures and Compilation Techniques (PACT)","volume":"68 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2010-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124374599","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"An empirical characterization of stream programs and its implications for language and compiler design","authors":"W. Thies, Saman P. Amarasinghe","doi":"10.1145/1854273.1854319","DOIUrl":"https://doi.org/10.1145/1854273.1854319","url":null,"abstract":"Stream programs represent an important class of high-performance computations. Defined by their regular processing of sequences of data, stream programs appear most commonly in the context of audio, video, and digital signal processing, though also in networking, encryption, and other areas. In order to develop effective compilation techniques for the streaming domain, it is important to understand the common characteristics of these programs. Prior characterizations of stream programs have examined legacy implementations in C, C++, or FORTRAN, making it difficult to extract the high-level properties of the algorithms. In this work, we characterize a large set of stream programs that was implemented directly in a stream programming language, allowing new insights into the high-level structure and behavior of the applications. We utilize the StreamIt benchmark suite, consisting of 65 programs and 33,600 lines of code. We characterize the bottlenecks to parallelism, the data reference patterns, the input/output rates, and other properties. The lessons learned have implications for the design of future architectures, languages and compilers for the streaming domain.","PeriodicalId":422461,"journal":{"name":"2010 19th International Conference on Parallel Architectures and Compilation Techniques (PACT)","volume":"61 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2010-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127038400","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Revisiting sorting for GPGPU stream architectures","authors":"D. Merrill, A. Grimshaw","doi":"10.1145/1854273.1854344","DOIUrl":"https://doi.org/10.1145/1854273.1854344","url":null,"abstract":"This poster presents efficient strategies for sorting large sequences of fixed-length keys (and values) using GPGPU stream processors. Compared to the state-of-the-art, our radix sorting methods exhibit speedup of at least 2x for all generations of NVIDIA GPGPUs, and up to 3.7x for current GT200-based models. Our implementations demonstrate sorting rates of 482 million key-value pairs per second, and 550 million keys per second (32-bit). For this domain of sorting problems, we believe our sorting primitive to be the fastest available for any fully-programmable microarchitecture. These results motivate a different breed of parallel primitives for GPGPU stream architectures that can better exploit the memory and computational resources while maintaining the flexibility of a reusable component. Our sorting performance is derived from a parallel scan stream primitive that has been generalized in two ways: (1) with local interfaces for producer/consumer operations (visiting logic), and (2) with interfaces for performing multiple related, concurrent prefix scans (multi-scan).","PeriodicalId":422461,"journal":{"name":"2010 19th International Conference on Parallel Architectures and Compilation Techniques (PACT)","volume":"4 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2010-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128936284","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
R. Ubal, J. Sahuquillo, S. Petit, P. López, J. Duato
{"title":"Exploiting subtrace-level parallelism in clustered processors","authors":"R. Ubal, J. Sahuquillo, S. Petit, P. López, J. Duato","doi":"10.1145/1854273.1854349","DOIUrl":"https://doi.org/10.1145/1854273.1854349","url":null,"abstract":"The performance evaluation has been carried out on top of the Multi2Sim 2.2 simulation framework [2], a cycle-accurate simulator for x86-based superscalar processors, extended to model a clustered architecture with support for independent subtraces generation. The parameters of the modeled machine are summarized in Table 1. The Mediabench suite has been used to stress the machine, and simulations are stopped after the first 100 million uops commit. The steering algorithm and the interconnection network among clusters are important design factors related with the criticality of the inter-cluster communication latency. For a good baseline performance, the modeled schemes use a sophisticated steering algorithm called topology-aware steering [3], and several interconnection networks with different realistic link delays are considered.","PeriodicalId":422461,"journal":{"name":"2010 19th International Conference on Parallel Architectures and Compilation Techniques (PACT)","volume":"124 15 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2010-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122282623","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Seth H. Pugsley, J. Spjut, D. Nellans, R. Balasubramonian
{"title":"SWEL: Hardware cache coherence protocols to map shared data onto shared caches","authors":"Seth H. Pugsley, J. Spjut, D. Nellans, R. Balasubramonian","doi":"10.1145/1854273.1854331","DOIUrl":"https://doi.org/10.1145/1854273.1854331","url":null,"abstract":"Snooping and directory-based coherence protocols have become the de facto standard in chip multi-processors, but neither design is without drawbacks. Snooping protocols are not scalable, while directory protocols incur directory storage overhead, frequent indirections, and are more prone to design bugs. In this paper, we propose a novel coherence protocol that greatly reduces the number of coherence operations and falls back on a simple broadcast-based snooping protocol when infrequent coherence is required. This new protocol is based on the premise that most blocks are either private to a core or read-only, and hence, do not require coherence. This will be especially true for future large-scale multi-core machines that will be used to execute message-passing workloads in the HPC domain, or multiple virtual machines for servers. In such systems, it is expected that a very small fraction of blocks will be both shared and frequently written, hence the need to optimize coherence protocols for a new common case. In our new protocol, dubbed SWEL (protocol states are Shared, Written, Exclusivity Level), the L1 cache attempts to store only private or read-only blocks, while shared and written blocks must reside at the shared L2 level. These determinations are made at runtime without software assistance. While accesses to blocks banished from the L1 become more expensive, SWEL can improve throughput because directory indirection is removed for many common write-sharing patterns. Compared to a MESI based directory implementation, we see up to 15% increased performance, a maximum degradation of 2%, and an average performance increase of 2.5% using SWEL and its derivatives. Other advantages of this strategy are reduced protocol complexity (achieved by reducing transient states) and significantly less storage overhead than traditional directory protocols.","PeriodicalId":422461,"journal":{"name":"2010 19th International Conference on Parallel Architectures and Compilation Techniques (PACT)","volume":"20 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2010-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125223504","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"An intra-tile cache set balancing scheme","authors":"Mohammad Hammoud, Sangyeun Cho, R. Melhem","doi":"10.1145/1854273.1854346","DOIUrl":"https://doi.org/10.1145/1854273.1854346","url":null,"abstract":"This poster describes an intra-tile cache set balancing strategy that exploits the demand imbalance across sets within the same L2 cache bank. This strategy retains some fraction of the working set at underutilized sets so as to satisfy far-flung reuses. It adapts to phase changes in programs and promotes a very flexible sharing among cache sets referred to as many-from-many sharing. Simulation results using a full system simulator demonstrate the effectiveness of the proposed scheme and show that it compares favorably with related cache designs on a 16-way tiled CMP platform.","PeriodicalId":422461,"journal":{"name":"2010 19th International Conference on Parallel Architectures and Compilation Techniques (PACT)","volume":"27 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2010-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114716713","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Scalable hardware support for conditional parallelization","authors":"Zheng Li, Olivier Certner, J. Duato, O. Temam","doi":"10.1145/1854273.1854297","DOIUrl":"https://doi.org/10.1145/1854273.1854297","url":null,"abstract":"Parallel programming approaches based on task division/-spawning are getting increasingly popular because they provide for a simple and elegant abstraction of parallelization, while achieving good performance on workloads which are traditionally complex to parallelize due to the complex control flow and data structures involved. The ability to quickly distribute fine-granularity tasks among many cores is key to the efficiency and scalability of such division-based parallel programming approaches. For this reason, several hardware supports for work stealing environments have already been proposed. However, they all rely on a central hardware structure for distributing tasks among cores, which hampers the scalability and efficiency of these schemes. In this paper, we focus on conditional division, a division-based parallel approach which provides the additional benefit, over work-stealing approaches, of releasing the user from dealing with task granularity and which does not clog hardware resources with an exceedingly large number of small tasks. For this type of division-based approaches, we show that it is possible to design hardware support for speeding up task division that entirely relies on local information, and which thus exhibits good scalability properties.","PeriodicalId":422461,"journal":{"name":"2010 19th International Conference on Parallel Architectures and Compilation Techniques (PACT)","volume":"2 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2010-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122712924","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}