MPI datatype processing using runtime compilation

Schneider, Timo; Kjølstad, Fredrik; Hoefler, Torsten

doi:10.1145/2488551.2488552

Cited by 22 publications

(18 citation statements)

References 17 publications

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“…Although better results have been reported by, for instance, Hoefler and Gottlieb (2010) and Lu et al (2004), this inconsistency seems to hamper the widespread use of derived datatypes. This, despite a considerable amount of work by Byna et al (2006), Ross et al (2003), Schneider et al (2013) and Wu et al (2004) among others addressing the issue. Schneider et al (2013) also demonstrate runtime compilation for MPI datatypes.…”

Section: Background and Related Workmentioning

confidence: 97%

DAME: Runtime-compilation for data movement

Prabhu

Gropp

2017

The International Journal of High Performance Computing Applica

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Modern machines consist of multiple compute devices and complex memory hierarchies. For many applications, it is imperative that any data movement between and within the various compute devices be done as efficiently as possible in order to obtain maximum performance. However, hand-optimizing code for one architecture will likely sacrifice both performance portability and software maintainability. In addition, some optimization decisions are best made at runtime. This suggests that the problem ought to be tackled on two fronts. First, provide the programmer with a declarative language to describe data layouts and data motion. This would allow the runtime system to be tuned for each architecture by a specialist and free the programmer to concentrate on the application itself. Second, exploit the execution time information to optimize the data movement code further. MPI derived datatypes accomplish the former task and Just In Time (JIT) compilation can be used for the latter. In this paper, we present DAME-a language and interpreter designed to be used as the backend for MPI derived datatypes. We also present DAME-L and DAME-X, two JIT-enabled implementations of DAME, all of which have been integrated into MPICH. We evaluate their performance on DDTBench and two mini-applications written with MPI derived datatypes and obtain communication speedups of up to 20 3 and miniapplication speedups of up to 3 3 .

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Section: Background and Related Workmentioning

confidence: 97%

DAME: Runtime-compilation for data movement

Prabhu

Gropp

2017

The International Journal of High Performance Computing Applica

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“…Although better results have been reported [3,7], this inconsistency seems to hamper the widespread use of derived datatypes. This, despite a considerable amount of work [2,12,13,15] addressing the issue. In [13], Schneider et al also demonstrate runtime compilation for MPI datatypes.…”

Section: Mpi Derived Datatypesmentioning

confidence: 99%

“…This, despite a considerable amount of work [2,12,13,15] addressing the issue. In [13], Schneider et al also demonstrate runtime compilation for MPI datatypes. Our approach is, we believe, more comprehensive than theirs.…”

Section: Mpi Derived Datatypesmentioning

confidence: 99%

Dame

Prabhu

Gropp

2015

Proceedings of the 22nd European MPI Users' Group Meeting

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In order to achieve high performance on modern and future machines, applications need to make effective use of the complex, hierarchical memory system. Writing performanceportable code continues to be challenging since each architecture has unique memory access characteristics. In addition, some optimization decisions can only reasonably be made at runtime. This suggests that a two-pronged approach to address the challenge is required. First, provide the programmer with a means to express memory operations declaratively which will allow a runtime system to transparently access the memory in the best way and second, exploit runtime information. MPI's derived datatypes accomplish the former although their performance in current MPI implementations shows scope for improvement. JIT-compilation can be used for the latter. In this work, we present DAME-a language and interpreter that is used as the backend for MPI's derived datatypes. We also present DAME-L and DAME-X, two JIT-enabled implementations of DAME. All three implementations have been integrated into MPICH. We evaluate the performance of our implementations using DDTBench and two mini-applications written with MPI derived datatypes and obtain communication speedups of up to 20x and mini-application speedup of 3x. CCS Concepts •Software and its engineering → Runtime environments; Just-in-time compilers; Parallel programming languages;

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“…MPI, for example, allows the specification of datatypes that simplify and optimize non-contiguous communications. We have shown in a previous study that runtime compilation techniques can speed up the packing of MPI DDTs by a factor of seven [19], and therefore make it competitive with manual packing. The proposed techniques in this work automatically overlap packing and communication to enable further optimization.…”

Section: O M I T T E D S O U T H E a S T And W E S T Unpack L Omentioning

confidence: 99%

“…Schneider et al [19] also optimized the packing of MPI derived datatypes. MPI DDTs are traditionally interpreted at runtime, which is often slower than manual pack loops written for a specific case and optimized by the compiler at compile time.…”

Section: Related Workmentioning

confidence: 99%

Compiler Optimizations for Non-contiguous Remote Data Movement

Schneider

Gerstenberger

Hoefler

2014

Lecture Notes in Computer Science

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Abstract. Remote Memory Access (RMA) programming is one of the core concepts behind modern parallel programming languages such as UPC and Fortran 2008 or high-performance libraries such as MPI-3 One Sided or SHMEM. Many applications have to communicate noncontiguous data due to their data layout in main memory. Previous studies showed that such non-contiguous transfers can reduce communication performance by up to an order of magnitude. In this work, we demonstrate a simple scheme for statically optimizing non-contiguous RMA transfers by combining partial packing, communication overlap, and remote access pipelining. We determine accurate performance models for the various operations to find near-optimal pipeline parameters. The proposed approach is applicable to all RMA languages and does not depend on the availability of special hardware features such as scatter-gather lists or strided copies. We show that our proposed superpipelining leads to significant improvements compared to either full packing or sending each contiguous segment individually. We outline how our approach can be used to optimize non-contiguous data transfers in PGAS programs automatically. We observed a 37% performance gain over the fastest of either packing or individual sending for a realistic application.

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MPI datatype processing using runtime compilation

Cited by 22 publications

References 17 publications

DAME: Runtime-compilation for data movement

DAME: Runtime-compilation for data movement

Dame

Compiler Optimizations for Non-contiguous Remote Data Movement

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