a. saà-garriga , d. castells-rufas and j. carrabina albert.saa@uabt

OMP2HMPP

A. Saà-Garriga et al., CAIAC (UAB) HIP3ES

1/22

A. Saà-Garriga, D. Castells-Rufas and J. [email protected]

Centre d’Intel·ligència Ambiental I Accessibilitat de Catalunya (CAIAC)

Universitat Autònoma de Barcelona. UAB

21/01/2014

OMP2HMPP: HMPP Source Code Generation fromPrograms with Pragma Extensions

OMP2HMPP


2/22

11 Introduction

22 OMP2HMPP Compiler

33 Results

44 Conclusions

Intro Compiler Results Conclusions

OMP2HMPP


3/22

11 Introduction


33 Results

44 Conclusions


OMP2HMPP


4/22

GPGPUS and Embedded Systems

One of the main integrated blocks on heterogeneous platforms

Mali GPUs (embedded systems)

NVIDIA GPUs in first 10 machines of Green Top 500 (Nov, 2013)

GPGPUs are potentially useful for speed up applications Both classical HPC and EHPC

Complex and error-prone due to the programming complexity and language paradigms


OMP2HMPP


5/22

Actual Programming Workflow


New Proposals Learning

Source Code

AdaptationVersion

Evaluation

• New language• Language extensions

•Language syntax•Programing paradigms

GPGPUs programming could become a hurdle that can limit their adoption, since the programmer has to learn the hardware capabilities and the language to work with these.

OMP2HMPP


6/22

Programming Alternatives


Directive Based Languages

New Languages

OpenACC[2] HMPP[3]

Language Extensions OpenMPC[4] hiCUDA[5]

Direct Transformations

Par4All[6]

Hide GPU complexity No automatic transfer optimization New list of directives

Hide GPU Complexity New Language

Hide GPU complexity No intermediate language No data transfer optimization Just C source code transformation

OMP2HMPP


7/22

Proposed Programming Workflow


OMP2HMPP

Hide GPU complexity

Just one new directive

Uses HPC standard as input

C/C++

New Proposals Learning

Source Code

AdaptationVersion

Evaluation

• New language• Language extensions

•Language syntax•Programing paradigms

OpenMP OMP2HMPP HMPP

• Mercurium Infrastucture.[J. Balart et al. EWOMP 2004]

OMP2HMPP


8/22Intro Compiler Results Conclusions

11 Introduction


33 Results

44 Conclusions

OMP2HMPP


9/22

Generate HMPP Directives


Callsite

Codelet

Group

Advanced Load

Delegate Store

Syncronize

…

OMP2HMPP


10/22

Generate HMPP Directives


OpenMP block Outlining

#pragma hmpp outlined_block codeletvoid outlined_block(int i, int A[10], int C[10]) { for(i=...) { ... C[i]=A[i]*k; ... }}

int main(){ ... A[x]=v;#pragma hmpp outlined_block callsite outlined_block(i,A,C); ... A[j]=C[j];}

OMP2HMPP


11/22

Contextual Information


For each of the variables used inside an OpenMP block to transform OMP2HMPP analyze the Abstract Syntax Tree to identify:

The next/last access (read/write)

Where is computed (CPU/GPU) this access

If an operation is made inside a loop and identify this one.

OMP2HMPP


12/22

Contextual information


Data Transfer Optimitzation

Advanced Load

Delegate Store

OMP2HMPP


13/22

Use of Contextual Information


Data Transfer Optimitzation (Loops)

OMP2HMPP


14/22

Use of Contextual Information


Data Transfer Optimitzation (Loops)

OMP2HMPP



11 Introduction


33 Results

44 Conclusions

OMP2HMPP


16/22

Source Code Example


OMP2HMPP


17/22

Experimental Results


B505(1) B505(2) B515Num.

Processors2 2 2

Processor E5640 E5640 E5-2400Memory 24Gb 24Gb 192Gb

GPU NVIDIA Tesla M2050

NVIDIATesla C2075

NVIDIATesla K20

Tested Architectures

OMP2HMPP


18/22



B505(1)

OMP2HMPP


19/22



B505(2)

OMP2HMPP


20/22



B515

OMP2HMPP



11 Introduction


33 Results

4 4 Conclusions

OMP2HMPP


22/22

Conclusions

The programmer avoid to expend time in learning.

Tested set of problems from Polybench[8] obtains an average speedup of 113x compared to sequential.

An average speedup over 31x compared to OpenMP.

OMP2HMPP gives a solution that rarely differ from the best HMPP hand-coded version.

OMP2HMPP establish a GPU parallel code reference point for expert developers that wants to refine the parallelization.

…thanks for your attention!


a. saà-garriga , d. castells-rufas and j. carrabina albert.saa@uabt

Documents