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Fuxianjun
Journeyman III

why float and float4 almost cost the same time ?

I test an addtion of two arrays with long length(for example 40000,e.g. a[40000]+b[40000]), and loop the same addtion many times(for example 100000 times). but this two kernels cost the same time, why ?

my gpu is ATI Radeon HD 5700 Series

// workitem number is 10000 __kernel void add(__global float4 * a, __global float4 * b, __global float4 * c) { int i = get_global_id(0); c=a*b; } // workitem number is 40000 __kernel void add(__global float * a, __global float * b, __global float * c) { int i = get_global_id(0); c=a*b; }

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genaganna
Journeyman III

Originally posted by: Fuxianjun I test an addtion of two arrays with long length(for example 40000,e.g. a[40000]+b[40000]), and loop the same addtion many times(for example 100000 times). but this two kernels cost the same time, why ?

 

my gpu is ATI Radeon HD 5700 Series

 

Are you measuring kernel only time?  What is your work group size?

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Jawed
Adept II

See this similar thread:

similar thread

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