MATLAB Answers

Adding just one line in my code slows the GPU.

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TAEYOON KIM
TAEYOON KIM on 18 Feb 2020
Commented: TAEYOON KIM on 19 Feb 2020
hello, my first code was
for i = 1:1000
r=0.8*r+0.2*tanh(A*r+W_in*xc(i+T0)+(0.3)*bias);
end
In the code above,the gpu is faster than cpu but I have to stack 'r' which is (nx1) matrix, so I just adding 'R' on previous code makes the gpu slower than cpu.
R=zeros(n,1000);
for i = 1:1000
r=0.8*r+0.2*tanh(A*r+W_in*xc(i+T0)+(0.3)*bias);
R(:,i)=r;
end
I want to make my code runs fast on gpu than cpu. What should I do??

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Answers (1)

Matt J
Matt J on 18 Feb 2020
Edited: Matt J on 18 Feb 2020
Pre-allocate on the GPU. Also, pre-compute things on the GPU that are easily vectorized and don't depend on r.
R=gpuArray.zeros(n,1000);
r=gpuArray(r);
A-gpuArray(A);
increments = W_in*gpuArray( xc((1:1000)+T0) ) + 0.3*bias;
for i = 1:1000
r=0.8*r+0.2*tanh(A*r+ increments(i));
R(:,i)=r;
end

  3 Comments

TAEYOON KIM
TAEYOON KIM on 19 Feb 2020
Sorry, I didn't write about pre-allocate. I pre-allocate all elements already. My prblem is when R(:,i)=r part makes for loop slow.
Matt J
Matt J on 19 Feb 2020
Still, my other recommendations should help...

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