Questions tagged [parallel-computing]
The study of solving computational problems by exploiting the use of multiple processors simultaneously.
253
questions
3
votes
1answer
73 views
Parallelizing Newton-method in solving non-linear systems
Circuit simulation software based on SPICE (such as ngspice) uses Newton-Raphson method to solve non-linear system of equations ...
3
votes
3answers
107 views
GPGPU computing, software selection
I am using an existing GCC C++ x86 Qt application that filters, displays and stores results computed by some C code. Since the computation by now got too complex for CPUs I intend to port the small C ...
1
vote
2answers
94 views
simulation outputs differ across hardware platforms
We've recently ported our Python/Fortran simulation code to a new supercomputer. Some (not all) of the tests (simulations) that we've run on the new platform yield results that are significantly ...
0
votes
0answers
59 views
How to make this parfor loop work properly in Matlab?
I have a code that does some calculations for a given value p (p is between 0 and 1). In theory I should be able to make a parfor loop that runs over the values of p, with p being a vector (for ...
2
votes
1answer
36 views
How to pass matrices to parallel workers quickly in matlab?
I am trying to solve many different linear systems in parallel in matlab. The problem is, each linear system has entirely different parts and are fairly large, so passing the information to each of ...
0
votes
1answer
76 views
Computer build for scientific or big data computing [closed]
I'm wanting to build a computer for scientific or big data computing (Python, Fortran, Matlab) and I was hoping to get some advice on the type of processor, memory, graphics, etc I would need.
I ...
2
votes
1answer
148 views
Why my parallel code using MPI is much slower than the serial one?
I know that is not the first time someone asks this question but I'm really confused.I'm new to MPI, and I tried to implement the Jacobi solver for a linear system $Ax=b$. I want to compare the time ...
1
vote
2answers
109 views
How to compute 16 different simulations on parallel with pbs script on the same machine
I have a 32 cores machine, and I need to run 16 different dynamics simulations in parallel on it. I want the 16 jobs to run in parallel, not sequentially, on the same machine. The 16 dynamics input ...
0
votes
1answer
37 views
Access PETSc data in totalview?
Is it possible to view the data stored in the various PETSc data types from within totalview?
Ordinarily, PETSc types are integers which act as pointers to the actual data (obviously my understanding ...
3
votes
1answer
62 views
Parallelizing FEM for elliptical PDEs with n >1
For a little personal project, I am picking up my FEM skills again. I learned a lot about the theory back in university and I am able to implement a simple FEM solver for specific problems but I was ...
2
votes
1answer
109 views
How to choose a python parallelization library?
I want to preprocess a relatively large dataset using python. I implemented some Dask parallelization and was stunned by the time reduction. I figure there are other libraries or frameworks I could ...
2
votes
2answers
188 views
C standard for computational science
Which C standard should be used for computational science code ?
Should we keep compatibility with C89/90/ANSI or jump to C99 or C11 ?
Context:
Code will use third-party : BLAS, LAPACK, MKL, ...
3
votes
2answers
132 views
Parallel assembly of matrix
I have a matrix which I want to assembly quickly, which is in block form:
$$
A = \pmatrix{ A_{11} & A_{12} & A_{13} \\ A_{21} & A_{22} & A_{23} \\ A_{31} & A_{32} & A_{33}}
$$
...
-1
votes
1answer
62 views
Writing parallel code for molecular computation [duplicate]
I recently moved towards computational biophysics from an experimental science background. As of now, I am learning the fundamentals and doing some basic monte carlo simulations of LJ fluid on my ...
2
votes
0answers
36 views
GPGPU/FPGA programming for Combinatorial Analysis
Recently, I have taken an interest in performing combinatorial analysis for the game of 21 (blackjack) and attempted to use my AMD APU to try and thread the program via the 4 cores on the chip. ...
1
vote
2answers
76 views
Guaranteed equality between binary results with increasing MPI processes
Testing on an MPI scientific code for compressible flow dynamics I noticed that the results may depend on the number of processors used for the calculation. In fact, comparing the binary files they ...
4
votes
1answer
106 views
Level scheduling of triangular sparse matrices
Assume one has a triangular sparse matrix and want to solve $Lx=b$ where $b$ and $L$ are known. This can be done easily by using forward substitution when $L$ is a lower triangular matrix. Forward ...
1
vote
1answer
145 views
Matlab parpool on Intel Xeon-Phi (KNL)
I am trying to run my matlab script on a Xeon Phi node with 68 physical cores. Using parpool I allocate 16 cores to enable SMD parallelization with a parfor loop. The script looks something like this.
...
6
votes
1answer
155 views
Solving linear system of the form $ABx=b$
I would like to solve a linear system of the form $ABx=b$ in parallel, where $A$ and $B$ are large, sparse matrices. Currently, I am forming the system matrix $AB$ explicitly, but I would like to ...
0
votes
2answers
121 views
How do I interpret the results from MPI_Wtime()?
Say, I have this code
double start = MPI_Wtime();
ParallelMatrixVectorProductRotuine(...);
double end = MPI_Wtime();
How do I interpret the numbers I am getting. ...
1
vote
2answers
145 views
MPI data broadcast or not in C
I have two slightly different but getting the same results MPI code.
The first one is from an open-source package having several data exchange steps in between:
...
8
votes
0answers
110 views
Review of modern homotopy methods and practical techniques
I'm hoping someone can recommend recent literature concerning homotopy methods for solving systems of nonlinear equations. Already by the time of Layne Watson's 1986 paper there were a lot of methods,...
5
votes
1answer
137 views
Parallel decomposition of 2D grid with minimal communication
Consider an $M\times N$ grid with periodicity in both dimensions upon which I want to do some local stencil-like computations using distributed-memory parallelism (MPI). I have two options for ...
0
votes
1answer
118 views
Parallelization of FEM calculations
I need to conduct some FEM calculations and I am wondering whether parallelization would be a good idea.
The trouble is that my model is not especially large so it takes few seconds to solve a single ...
1
vote
1answer
95 views
Parallel integration of dynamical systems
I need to solve the following problem:
$$ \begin{cases}
\dot{\vec{x(t)}} = A\vec{x(t)} + u(t)D\vec{x(t)} + u(t)\vec{b}, & x \in (0, T), \\
\vec{x(0)} = \vec{0},
\end{cases}$$
where $u(t)$ is known ...
1
vote
1answer
76 views
PBS: Using different computational resources on different nodes
I am using an HPC cluster to launch parallel simulations. At the moment, there are 48 free cores over 4 nodes but not each node do not have the same number of free cores. The distribution is something ...
1
vote
1answer
152 views
Efficiency of parallel direct linear solver
I am currently working on solving a positive definite symmetric systems in parallel. The parallel direct solver I used is MUMPS. However, the performance and efficiency of the parallel direct solver ...
2
votes
1answer
49 views
Test on a set of high degree polynomials whose coefficients in {-1,0,1}
I'm looking for the best way of implementing the following algorithm: consider the set of all polynomials with a high degree (say, degree 30) whose coefficients ranges from a given set of values (say, ...
2
votes
1answer
112 views
Which iterative method and preconditioner from petsc should be used when solving linear algebra in parallel?
I am currently trying to parallelize the incompressible flow solver code.
However, when I run the code I realise that the parallel code takes much longer time than sequential code to finish one ...
0
votes
1answer
120 views
Why does multithreaded code Segfault in 64-bit but not 32-bit [closed]
I have written some multithreaded code using PyOpenCL, which works fine under the following conditions:
GPU 32-bit floating point values (Intel Iris GPU can only handle single precision values)
CPU ...
1
vote
1answer
678 views
General understanding of Intel MKL, threads and MPI
Preface
I seem to lack a fundamental understanding of best practise recommendations given by Intels MKL user guides for using MKL in threaded applications. So let's clarify it together.
Wording and ...
2
votes
0answers
57 views
Parallel compact schemes using the Parallal Diagonal Dominant (PDD) algorithm
I would like to use the PDD algorithm developed by Sun to solve tridiagonal matrices in parallel for the following compact finite difference scheme:
$
\begin{align}
\dfrac{1}{4}f^{'}_{i-1} + f^{'}_i +...
1
vote
1answer
140 views
Parallel calculation in finite elements
I am trying to solve a 1 Dimensional eigenvalue of poisson problem:
$$\nabla \phi ^2 +\nabla \phi = k\phi$$
with the boundary condition: $\phi (0)=0 , \nabla \phi(1) = 0 $.
I could solve this ...
1
vote
1answer
130 views
Why is FLOP(Floating Point Operations Per Second) mentioned as a specification on every GPU?
Counting FLOP may not be representative of the actual algorithm real world performance but still all the GPU manufacturers mention FLOPS as a metric of Performance on GPU. Is there any way that this ...
0
votes
1answer
70 views
How to improve the efficiency when I need to exhaustively pairwise millions of list in Python?
I have a m*n matrix (m>1000000, n>50000). What I want to do now is to pairwise every two rows of the matrix and do some further computation (e.g computing common elements of two rows, or reveal ...
1
vote
0answers
53 views
Algorithm design to filter on 5,000 stocks each of which has 4 months worth of data points
I want to filter on 5000 stocks, each of which has 4 month or more worth of data (>= 500 data points each). my filtering criteria will be based on 8 calculated values from the data points. for example,...
1
vote
0answers
58 views
Parallel dense solve with submatrices from mesh refinement with Petsc
For a Bounday Element Method problem I require the solution of a system of linear equations with multiple right-hand sides. Though this is a dense system, I still want to do it via Petsc in parallel. ...
2
votes
5answers
617 views
c++ Libraries for large linear system of equations
I am looking for libraries for solving large scale linear system (10e5) of equations using parallelization and shared memory.
1. Sparse, complex symmetric, SPD.
2. Suitable for higher order FEM ,...
0
votes
1answer
96 views
Need clarification on a piece of book excerpt about spectral element method!
I am reading "Using MPI (3rd edition)" from William Gropp, where in chapter 4 application section 4.13, it introduces an MPI application Nek5000/NekCEM which is based on spectral element method (SEM) ...
2
votes
0answers
480 views
Scalability of Julia language [closed]
The Julia language has caught my attention as I am a heavy MATLAB user, but would like more performance. Julia looks attractive as skipping the whole 'prototype in MATLAB then rewrite code in FORTRAN/...
1
vote
0answers
52 views
Parallelizing molecular simulation with full configuration energy
First, let just me stress that I'm not a an expert in computation chemistry, so now the problem:
We have GCMC molecular simulation, in the Grand Canonical ensemble, using the standard metropolis ...
0
votes
1answer
94 views
What exactly is Hardware Acceleration?
I'm able to find many definitions and notions to this term including,
Implementing the algorithm (or part of it) in hardware :- Instructions like FMAD; FPGAs
Parallelizing the algorithm at the ...
0
votes
1answer
101 views
Sun Grid Engine peculiarities
I don't know if anyone is using SGE anymore (what is the world of HPC using nowadays?), but I need to work on version 6.2u3, I believe, from sometime back in '11. I'm using it on a cluster of 64 nodes,...
0
votes
2answers
126 views
Halo Region Communication in Unstructured Mesh Problems
I'm currently using ParMETIS and it is required to determine the halo region of the local elements in a parallel unstructured mesh. Assume that the mesh is large and cannot be stored on a single ...
0
votes
1answer
86 views
Generate a set of random x,y,z numbers, with a minimum difference between them, between defined limits
So I am trying a molecular dynamics simulation, and trying to populate a 3D rectangular volume with random particles which are uniformly distributed throughout the volume. Each molecule has a fixed ...
3
votes
3answers
2k views
A good, simple book/resource on Parallel Programming in C++ for scientific computing
I am a Mechanical Engineering grad student, currently working on a project which will be scaled up in the new future to require quite some processing power. I am using C++ for the code that I have, ...
0
votes
1answer
61 views
simple and fast graph-clustering for paralelization of finite element simulations
I'm learning to use OpenCL to optimize some of my simulations. I realized that I need some sort of Graph-clustering or graph-partitioning to exploit efficiently local memory for un-ordered meshes.
...
2
votes
0answers
107 views
scalable parallel mesh/amr on unstructured grid
I am trying to code a scalable parallel AMR for unstructured grid. There seems to be three approaches for this
a) Store some global grid info on each processor and partition with parmetis (The ...
5
votes
2answers
228 views
Speeding up a linear transform using Python
In an optical wavefront propagation problem, I need to do excessive Fourier-type computations:
...
0
votes
1answer
46 views
Balancing core load when number of particles in cells vary (PIC on GPU)
Consider this basic scheme for particle in cell simulations ( with just short-range interactions ):
assign particles to disjunct cells
for cell $A$ go over neighboring cells $B$
for each particle $...
