Loop with GPU arrayfun

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Maxime Rivard 2017-12-21

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/374139-loop-with-gpu-arrayfun

评论： Joss Knight 2018-1-16

I'm looking at the Matlab example on rendering Fractals with GPUs ( https://www.mathworks.com/help/distcomp/examples/illustrating-three-approaches-to-gpu-computing-the-mandelbrot-set.html ) and it works fine. But I want to loop this, and I get this error:

Error using gpuArray.linspace
An unexpected error occurred trying to launch a kernel. The CUDA
error was:
invalid configuration argument
Error in matlabArrFunLoop (line 11)
x = gpuArray.linspace( xlim(1)/k, xlim(2)/k, gridSize );

What's wrong with looping this code? Thanks

Code:

clear
close all
gridSize = 3000;
xlim = [-0.748766713922161, -0.748766707771757];
ylim = [ 0.123640844894862,  0.123640851045266];
for k=1:1:3
% Setup
tic
k
x = gpuArray.linspace( xlim(1)/k, xlim(2)/k, gridSize );
y = gpuArray.linspace( ylim(1)/k, ylim(2)/k, gridSize );
[xGrid,yGrid] = meshgrid( x, y );
% Calculate
count = arrayfun( @iterFunc,xGrid, yGrid );
% Show
count = gather( count ); % Fetch the data back from the GPU
figure(3)
imagesc( x, y, count )
axis off
toc
end
function count = iterFunc(x0,y0)
maxIterations=5000;
z0 = complex(x0,y0);
z = z0;
count = 1;
while (count <= maxIterations) && (abs(z) <= 2)
    count = count + 1;
    z = z*z + z0;
end
count = log(count);
end

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Walter Roberson 2017-12-22

在 MATLAB Online 中打开

I get that message, but first I get

Error using gpuArray/arrayfun
The GPU has timed out. See www.mathworks.com/gputimeout for details about GPU timeouts and how to avoid them.

I have some other things going on with my computer at the moment which might be trying to use some of the GPU cycles. But just in general, gpu can time out if the work it is asked to do takes longer then the kernel hold time that is imposed for GPUs that are not in exclusive mode.

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采纳的回答

Matt J 2017-12-22

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/374139-loop-with-gpu-arrayfun#answer_297390

The code runs fine for me. Try restarting MATLAB and/or the computer.

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Hoang Nguyen 2018-1-8

Hello Joss, is there any problem if we disable timeouts by your suggestion. In fact, I could run any examples utilizing GPU but not so sure about consequences since that registry key is not built-in.

Joss Knight 2018-1-16

There is potential for system lock-up if you are using perhaps less rigorous GPU code that may contain bugs. If the graphics card can't draw graphics because it's locked up running some CUDA kernel then to all intents and purposes your system has crashed.

But this is very rarely an issue for most people.

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