Computational Science Stack Exchange
Computational Science Stack Exchange

Questions tagged [parallel-computing]

The study of solving computational problems by exploiting the use of multiple processors simultaneously.

323 questions
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Are there any famous problems/algorithms in scientific computing that cannot be sped up by parallelisation

Are there any famous problems/algorithms in scientific computing that cannot be sped up by parallelisation? It seems to me whilst reading books on CUDA that most things can be.
RNs_Ghost
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Will upgrading to a 64 bit OS help me any?

Assuming that I am running Intel MKL (BLAS, LAPACK), is there any difference in performance if I run it on a 32 or 64 bit OS? (Of course, assuming that my hardware remains the same). My processor is a 64 bit Intel i3. But am currently running…
Inquest
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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 decomposing this problem: (1) split the grid along one…
coolguy1000000
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Any useful application for smartphones in the world of computational science?

I was having this discussion with a colleague of mine a week ago and thought I might as well bring it here to a broader audience. That said, I am not certain this is a kind of question that is appropriate for scicomp. Anyhow, given their abundance…
mmirzadeh
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Under which conditions is better OMP_NUM_THREADS = 4 or 2 for multithread two-core CPU?

I am running my Fortran 95 numerical codes, whose structure is most times easily parallelized by little more than simply adding the corresponding OpenMP instruction before some critical DO sentences, in a dual-core multi-thread CPU Intel CORE i3.…
user4015
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3 answers

Does IBM LSF facilitate parallel computing?

I have been browsing through the documentation of the IBM Platform Load Sharing Facility, to find out if it supports parallel task computing. Below is what I think is relevant for this question, Please correct me if my perception is wrong. Focus…
R. Schreurs
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Can you provide an example of an algorithm that has strong scalability but not weak scalability? Can you also provide an example the other way around?

Strong Scaling and Amdahl's Law Strong scaling is a measure of how, for a fixed overall problem size, the time to solution decreases as more processors are added to a system. An application that exhibits linear strong scaling has a speedup equal to…
hzhaoc
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How useful is a Xeon Phi for a general workstation

I do a lot of general processing of data on my desktop computer. It can be stuff like extracting timeseries of point measurements from a large number of NetCDF files, or converting csv-files into binary or making a lot of plots. My question is,…
Tor
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One cancels the other qsub semantics atop SGE?

Is there a way to achieve "one cancels the other" semantics (http://www.investopedia.com/terms/o/oco.asp) for qsub jobs submitted to Sun Grid Engine? That is, I submit two (or more) jobs and when one of them runs it cancels the others? Two…
Rhys Ulerich
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How can I write a GPGPU program that can run on any GPU?

Here is my objective: I want to code a ray tracing engine in C++ that can be run on any GPU. That means that it should work on NVIDIA GPUs, AMDs, or even Intel Graphics chipsets. The choice of C++ was made because the final program will be used by a…
Balfar
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On an HPC machine, does one compute node equate to one motherboard?

I am using the Hydra Process Manager from MPICH and I plan on running jobs on multiple compute nodes. Currently working with an Intel Xeon E5-2680v2 with a total of 20 cores with 2 sockets (32 GB of memory and 25 MB L3 cache for each socket). Socket…
Justin
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Is there a mathematical algorithm that can determine whether a problem is parallelizable?

Is there a mathematical algorithm that can determine whether a problem is parallelizable? Possibly similar to how the definition for "computable" works out: https://en.wikipedia.org/wiki/Computable_function So a parallelizable program is a program…
mavavilj
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openmp critical

Following this question, for the code below (from MS OpenMP docs example) // omp_critical.cpp // compile with: /openmp #include #include #include #define SIZE 10 int main() { int i; int max; int a[SIZE]; …
user123
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Openmp critical section inside if conditional statement

I have a function like this void foo(x, *y) { some calculations if (x > *y) { *y = x/2; } more calculations } My parallel section is int x[] = some array; double y=0; #pragma omp parallel for for ( int i = 0; i<=n; i++)…
user123
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Parallel slower than serial

Issue Hello everyone, I have got a program (from the net) that I intend to speed up by converting it into its parallel version thru the use of pthreads surprisingly though, it runs slower than the serial version. Below is the program: # include…
Jones G
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