OpenMP Architecture Review Board. OpenMP: a Proposed Industry Standard API for Shared Memory Programming. White Paper, http://www.openmp.org/, October 1997.  Home/Search   Document Not in Database   Summary   Related Articles   Check

....is an important prerequisite. HPF 2 [12] offers limited task parallelism, which is based on group splitting, but within each group there is still a single thread of control. As NestStep is a more general MIMD language, compiler techniques for HPF can be applied only in special cases. OpenMP [11] allows general MIMD computations and provides constructs that control processor subset synchronization and consistency for individual variables. Groupwide sequential consistency is automatically enforced at explicit and implicit group wide barriers, for example. A BSP style of programming is thus ....

OpenMP Architecture Review Board. OpenMP: a Proposed Industry Standard API for Shared Memory Programming. White Paper, http://www.openmp.org/, Oct. 1997.

....as MPICH [33] and LAM [59] as well as native, vendor implementations from Sun Microsystems and IBM. Shared memory programming may use POSIX threads [63] from a freely available implementation (e.g. 56] or from a commercial vendor s platform. Much attention has been devoted lately to OpenMP [60], a standard for compiler directives and runtime support to reveal algorithmic concurrency and thus take advantage of shared memory architectures; once again, implementations of OpenMP are available both in open source and from commercial vendors. There are also several higher level parallel ....

....hardware that a#ect the balance of communication and computation costs a true sharedmemory machine exhibits very di#erent behavior from that of a cluster based on commodity networks. Another reason is that the communication libraries and parallel programming environments (e.g. MPI [50] OpenMP [60], and High Performance Fortran [41] as well as the parallel algorithm packages (e.g. fast Fourier transforms using FFTW [30] or parallelized linear algebra routines in ScaLAPACK [24] often exhibit di#ering performance on di#erent types of parallel platforms. When multiple library packages ....

OpenMP Architecture Review Board. OpenMP: A Proposed Industry Standard API for Shared Memory Programming. www.openmp.org, 1997.

....MPI (e.g. LAM 6.1 [25] MPICH 1.1.0 [14] or CHIMP 2.1.1c [1] and POSIX threads (pthreads) a standard (IEEE Std. 1003.1c [28, 31] portable threads library (e.g. DECthreads [10] or freely available pthreads implementations [29, 23] Alternatively, the OpenMP shared memory programming API [26] may be used to provide shared memory support. Each DEC AlphaServer 2100 4#275 node is a symmetric multiprocessor with four 64 bit, dual issue, DEC 21064A (EV4) Alpha RISC processors clocked at 275 MHz. Each Alpha chip has two separate data and instruction on chip caches. Both on chip caches are ....

OpenMP Architecture Review Board, OpenMP: A Proposed Industry Standard API for Shared Memory Programming, October 1997." [http:##www.openmp.org#]

....Flight Center, and large SGI Origin arrays at Ames Research Center) Hardware benchmark results reveal awesome performance rates for each component; however, few applications on SMP clusters ever reach a fraction of these peak speeds. While methodologies for symmetric multiprocessors (e.g. OpenMP [21] or POSIX threads [22] and message passing primitives for clusters (e.g. MPI [20] are well developed, performance dictates the use of a hybrid solution. We present preliminary results of our complexity model and programming methodology that is based hierarchically upon realistic model ....

OpenMP Architecture Review Board. OpenMP: A Proposed Industry Standard API for Shared Memory Programming. http://www.openmp.org/, October 1997.

....Since most compilers implement parallelization directives as threads, these two ways of programming parallel machines are related. While a large number of vendor speci c parallelization directives have served the SMP user community, there was a dire need for standardization. The OpenMP API [8] (Application Programmer s Interface) has ful lled the need by providing a exible, scalable, and fairly comprehensive set of compiler directives, library routines, and environment variables to incrementally write parallel programs. OpenMP is still evolving to better accommodate needs of the ....

OpenMP Forum, http://www.openmp.org. OpenMP: A Proposed Industry Standard API for Shared Memory Programming, October 1997.

....using MPI (e.g. LAM 6.1 [25] MPICH 1.1.0 [15] or CHIMP 2.1.1c [1] and POSIX threads (pthreads) a standard (IEEE Std. 1003.1c [28, 31] portable threads library (e.g. DECthreads [10] or freely available pthreads implementations [29, 23] Alternatively, the OpenMP shared memory programming API [26] may be used to provide shared memory support. Each DEC AlphaServer 2100 4 275 node is a symmetric multiprocessor with four 64 bit, dual issue, DEC 21064A (EV4) Alpha RISC processors clocked at 275 MHz. Each Alpha chip has two separate data and instruction on chip caches. Both on chip caches are ....

OpenMP Architecture Review Board. OpenMP: A Proposed Industry Standard API for Shared Memory Programming. http://www.openmp.org/, October 1997.

....at long last to take advantage of 20 years of research in PRAM algorithms for various irregular computations. Moreover, as supercomputers increasingly use SMP clusters, SMP computations will play a significant role in supercomputing. For instance, much attention has been devoted lately to OpenMP [35], which provides compiler directives and runtime support to reveal algorithmic concurrency and thus take advantage of the SMP architecture; and to mixed mode programming, which combines messagepassing style between cluster nodes (using MPI [31] and shared memory style within each SMP (using ....

OpenMP Architecture Review Board. OpenMP: A Proposed Industry Standard API for Shared Memory Programming. http://www.openmp.org/, October 1997.

....us at last to take advantage of 20 years of research in PRAM algorithms for various irregular computations. Moreover, as supercomputers increasingly use SMP clusters, SMP computations will play a significant role in supercomputing. For instance, much attention has been devoted lately to OpenMP [17], that provides compiler directives and runtime support to reveal algorithmic concurrency and thus takes advantage of the SMP architecture; and to mixed mode programming, that combines messagepassing style between cluster nodes (using MPI) and shared memory style within each SMP (using OpenMP or ....

OpenMP Architecture Review Board. OpenMP: A proposed industry standard API for shared memory programming. www.openmp.org, October 1997.

....as MPICH [33] and LAM [60] as well as native, vendor implementations from Sun Microsystems and IBM. Shared memory programming may use POSIX threads [64] from a freely available implementation (e.g. 57] or from a commercial vendor s platform. Much attention has been devoted lately to OpenMP [61], a standard for compiler directives and runtime support to reveal algorithmic concurrency and thus take advantage of shared memory architectures; once again, implementations of OpenMP are available both in open source and from commercial vendors. There are also several higher level parallel ....

....that affect the balance of communication and computation costs a true shared memory machine exhibits very different behavior from that of a cluster based on commodity networks. Another reason is that the communication libraries and parallel programming environments (e.g. MPI [51] OpenMP [61], and High Performance Fortran [42] as well as the parallel algorithm packages (e.g. fast Fourier transforms using FFTW [30] or parallelized linear algebra routines in ScaLAPACK [24] often exhibit differing performance on different types of parallel platforms. When multiple library packages ....

OpenMP Architecture Review Board. OpenMP: A Proposed Industry Standard API for Shared Memory Programming. www.openmp.org, 1997.

....Since most compilers implement parallelization directives as threads, these two ways of programming parallel machines are related. While a large number of vendor specific parallelization directives have served the SMP user community, there was a dire need for standardization. The OpenMP API [8] (Application Programmer s Interface) has fulfilled the need by providing a flexible, scalable, and fairly comprehensive set of compiler directives, library routines, and environment variables to incrementally write parallel programs. OpenMP is still evolving to better accommodate needs of the ....

OpenMP Forum, http://www.openmp.org. OpenMP: A Proposed Industry Standard API for Shared Memory Programming, October 1997.

....cations to support OpenMP and SMP, the base TreadMarks system remains unchanged from the original version. The OpenMP API is a set of compiler directives and callable run time library routines that extend a sequential language (currently, FORTRAN, C and C ) to express shared memory parallelism [2]. In C, the extensions are in the form of #pragma directives. OpenMP uses the fork join model of parallelism: multiple threads are spawned (and later joined) to execute a section of code in parallel. Sequential sections of the code are executed by the single master thread. There are three kinds of ....

OpenMP Architecture Review Board. OpenMP: A proposed industry standard API for shared memory programming. http://www.openmp.org, October 1997.

....the backend compiler does not detect this fact and disables the allocation of factor in a register. 3.4. MDG In MDG, two parallel loops INTERF DO1000 and POTENG DO2000 take more than 98 of the total serial execution time. Figure 5 shows the speedups of these two x The OpenMP definition [10] does not state the assumed memory consistency model explicitly. Where Does the Speedup Go: Modeling Performance Losses in Shared Memory Programs 9 loops. MOERAE and OpenMP yield the best performance in each loop. MDG has good locality of about 97 for read and 94 for write in both serial and ....

OpenMP Forum, http://www.openmp.org/. OpenMP: A Proposed Industry Standard API for Shared Memory Programming, October 1997.

....using MPI (e.g. LAM 6.1 [25] MPICH 1.1.0 [14] or CHIMP 2.1.1c [1] and POSIX threads (pthreads) a standard (IEEE Std. 1003.1c [28, 31] portable threads library (e.g. DECthreads [10] or freely available pthreads implementations [29, 23] Alternatively, the OpenMP shared memory programming API [26] may be used to provide shared memory support. Each DEC AlphaServer 2100 4 275 node is a symmetric multiprocessor with four 64 bit, dualissue, DEC 21064A (EV4) Alpha RISC processors clocked at 275 MHz. Each Alpha chip has two separate data and instruction on chip caches. Both on chip caches are 16 ....

OpenMP Architecture Review Board. OpenMP: A Proposed Industry Standard API for Shared Memory Programming. http://www.openmp.org/, October 1997.

....first parallel step consists of 9 jobs, the second parallel step consists of 6 jobs. memory parallel machine irrespective of the number of machines that participate in a given execution. This programming model is sometimes referred to as a block structured parbegin parend or fork join model [13, 25]. Unlike other programming models where programs are decomposed (into several files or functions) for parallel execution, this model together with shared memory semantics, allows loop level parallelization. As a result, given a working sequential program it is fairly straightforward to parallelize ....

OpenMP Architecture Review Board. OpenMP: A Proposed Industry Standard API for Shared Memory Programming, 1997.

....exploiting task parallelism in which autonomous tasks need to synchronize either to obtain exclusive access to shared resources or because they are organized as a pipeline in which data structures are produced and consumed concurrently. 4. 1 Shared Memory MIMD Languages We discuss FORTRAN OpenMP [35] which is a new industry standard API for sharedmemory parallel programming, and contrast it with the more expression oriented approach of Multilisp [22] 4.1.1 OpenMP OpemMP is a set of compiler directives and runtime library routines that can be used to extend FORTRAN and C to express ....

OpenMP Organization. OpenMP: A proposed industry standard API for shared memory programming. available from http://www.openmp.org.

....vx(i) ry(i) ry(i) TS vy(i) end do end do Figure 11: A dynamic single loop with one subscript array and two reduction arrays from the MD code multiprocessor, with 32 250MHz R10000 processors, a main memory of 8192 Mbytes, and a second level cache of 4Mbytes for each processor. The OpenMP [15] shared memory directives have been used to carry out the parallelization of the loops [18, 19] The array expansion based parallel code used for comparison purposes was obtained using the Polaris compiler. All parallel codes (the DWA LIP based loops and the Polaris output) were compiled using the ....

....traverses all iterations and check whether the data referenced in the current iteration belongs to it. The processor executes the calculation if the data belongs to it; otherwise it skips this iteration. A similar approach may also be exploited into HPF [10] for example, using ON HOME) or OpenMP [15]. However, when multiple reduction arrays occur, conditional sentences usually appear inside the reduction loop in order to ful ll the owner compute rule (which may introduce also computation replication) These implementations reduce drastically the performance of the parallel code and compromise ....

OpenMP Architecture Review Board. OpenMP: A Proposed Industry Standard API for Shared Memory Programming, 1997.

....multiple irregular reductions from the MD code the subscript array is updated periodically. The experiments have been conducted on a SGI Origin2000 multiprocessor, with 32 250MHz R10000 processors, a main memory of 8192 Mbytes, and a second level cache of 4Mbytes for each processor. The OpenMP [14] shared memory directives have been used to carry out the parallelization of the loops [17, 18] The array expansion parallel code used for comparison purposes was obtained using the Polaris compiler. All parallel codes (the dwa lip based loops and the Polaris output) were compiled using the SGI ....

....traverses all iterations and check whether the data referenced in the current iteration belongs to it. The processor executes the calculation if the data belongs to it; otherwise it skips this iteration. A similar approach may also be exploited into HPF [9] for example, using ON HOME) or OpenMP [14]. However, when multiple reduction arrays occur, conditional sentences usually appear inside the reduction loop in order to fulfill the owner compute rule (which may introduce also computation replication) These implementations reduce drastically the performance of the parallel code and ....

OpenMP Architecture Review Board, OpenMP: A Proposed Industry Standard API for Shared Memory Programming, http: www.openmp.org, 1997.

....number of nodes, communication hardware, operating systems, libraries, etc. despite commoditization. Traditionally, portability amongst diverse parallel computers have been either achieved by standard libraries such as MPI, or parallel programming languages and compilers such as HPF and OpenMP[Ope97] However, such efforts will could require programming under a fixed programming model. Moreover, portable implementation of such systems themselves are quite difficult and require substantial effort and cost. Instead, Reflection and open compilers could be alternative methodologies and ....

....will be dynamic, transient memory bugs. By using reflection, OMPC was created by only small set of customization in the underlying workings of the C , and is easily understandable, thus being easily maintainable, customizable, and portable. As a common shared memory programming API, OpenMP[Ope97] has been proposed as a standard. In OpenMP, the user adds appropriate annotations to the source code to indicate potential SPMD parallelism and distribution to sequential code, and the compiler emits the appropriate parallel code. OpenMP suffers from the same problem as Midway, as customized ....

OpenMP Architecture Review Board. OpenMP: A Proposed Industry Standard API for Shared Memory Programming., Oct. 1997.

....steps. It is important to note that parallel programs are written for a virtual sharedmemory parallel machine irrespective of the number of machines that participate in a given execution. This programming model is sometimes referred to as a block structured parbegin parend or fork join model [13, 25]. Unlike other programming models where programs are decomposed (into several files or functions) for parallel execution, this model together with shared memory semantics, allows loop level parallelization. As a result, given a working sequential program it is fairly straightforward to parallelize ....

OpenMP Architecture Review Board. OpenMP: A Proposed Industry Standard API for Shared Memory Programming, 1997.

....programs, and in Section III, we present our data locality tool, ParaSim. The tool was implemented for collecting the proposed locality information, and it can run parallel programs written using the Sun iMPACT directive language [6] the Polaris MOERAE thread based form [7] and the OpenMP API [8]. Section IV gives the case study presenting the analysis of the Perfect Benchmark FLO52, and Section V concludes the paper. II. Classification of Data Locality in Parallel Programs We extend the classification in [3] for loop based parallel applications executed on SMP machines. Unlike serial ....

....runs the programs in parallel on SMP machines. The codes can be compiled by various parallelizing compilers such as the Sun parallelizing compiler (AutoPar) 6] and Polaris [14] using the Sun directive sets [14] thread based codes generated from Polaris with MOERAE backend [7] and the OpenMP API[8]. ParaSim traces and collects real addresses generated on the SMPs. We augment the parallel code at the assembly level. Unfortunately few tools for such augmentation have been implemented for SPARC multiprocessor machines [15] Two tools are widely used for augmentation on SPARC machines, not for ....

OpenMP Forum, http://www.openmp.org/. OpenMP: A Proposed Industry Standard API for Shared Memory Programming, October 1997.

....are only supported by the Exemplar programming model) This is a serious drawback, especially for those applications that are designed to run efficiently across a wide range of machines. There is an urgent need to design a common interface for distributed shared memory programming (similar to the OpenMP interface [OpenMP] Acknowledgments We thank Steven Landherr and Mark Davis, both from HP Convex, for providing useful information on the Exemplar architecture and file system. We also thank Tina Mihaly for reviewing earlier drafts of this paper, Tom Cormen for his comments on various versions ....

....by the Exemplar programming model) This is a serious drawback, especially for those applications that are designed to run efficiently across a wide range of machines. There is an urgent need to design a common interface for distributed shared memory programming (similar to the OpenMP interface [OpenMP] Acknowledgments We thank Steven Landherr and Mark Davis, both from HP Convex, for providing useful information on the Exemplar architecture and file system. We also thank Tina Mihaly for reviewing earlier drafts of this paper, Tom Cormen for his comments on various versions of the abstract, ....

OpenMP Consortium. OpenMP: A Proposed Industry Standard API for Shared Memory Programming, October 1997. www.openmp.com.

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OpenMP Architecture Review Board. OpenMP: a Proposed Industry Standard API for Shared Memory Programming. White Paper, http://www.openmp.org/, October 1997.

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OpenMP Forum, \OpenMP: A Proposed Industry Standard API for Shared Memory Programming," http://www.openmp.org, Oct. 1997.,

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OpenMP Architecture Review Board, OpenMP: A Proposed Industry Standard API for Shared Memory Programming, www.openmp.org, 1997.

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OpenMP Forum, "Openmp: A proposed industry standard api for shared memory programming," Tech. Rep., Oct. 1997.

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