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Running Python script on GPU.

  • Difficulty Level : Medium
  • Last Updated : 16 Oct, 2019

GPU’s have more cores than CPU and hence when it comes to parallel computing of data, GPUs performs exceptionally better than CPU even though GPU has lower clock speed and it lacks several core managements features as compared to the CPU.
Thus, running a python script on GPU can prove out to be comparatively faster than CPU, however it must be noted that for processing a data set with GPU, the data will first be transferred to the GPU’s memory which may require additional time so if data set is small then cpu may perform better than gpu.
Getting started:
Only NVIDIA GPU’s are supported for now and the ones which are listed in this page. If your graphics card has CUDA cores, them u can proceed further with setting up things.
First make sure that Nvidia drivers are upto date also you can install cudatoolkit explicitly from here.then install Anaconda add anaconda to environment while installing.
After completion of all the installations run the following commands in the command prompt.

conda install numba & conda install cudatoolkit

NOTE: If Anaconda is not added to the environment then navigate to anaconda installation and locate the Scripts directory and open command prompt there.


We will use the numba.jit decorator for the function we want to compute over the GPU. The decorator has several parameters but we will work with only the target parameter. Target tells the jit to compile codes for which source(“CPU” or “Cuda”). “Cuda” corresponds to GPU. However, if CPU is passed as an argument then the jit tries to optimize the code run faster on CPU and improves the speed too.

from numba import jit, cuda
import numpy as np
# to measure exec time
from timeit import default_timer as timer   
# normal function to run on cpu
def func(a):                                
    for i in range(10000000):
        a[i]+= 1      
# function optimized to run on gpu 
@jit(target ="cuda")                         
def func2(a):
    for i in range(10000000):
        a[i]+= 1
if __name__=="__main__":
    n = 10000000                            
    a = np.ones(n, dtype = np.float64)
    b = np.ones(n, dtype = np.float32)
    start = timer()
    print("without GPU:", timer()-start)    
    start = timer()
    print("with GPU:", timer()-start)

Output: based on CPU = i3 6006u, GPU = 920M.

without GPU: 8.985259440999926
with GPU: 1.4247172560001218

However, it must be noted that the array is first copied from ram to the GPU for processing and if the function returns anything then the returned values will be copied from GPU to CPU back. Therefore for small data sets the speed of CPU is comparatively faster but the speed can be further improved even for small data sets by passing target as “CPU”. Special care should be taken when the function which is written under the jit attempts to call any other function then that function should also be optimized with jit else the jit may produce even more slower codes.

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