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Thread: concurrent access to global memory

  1. #1
    Junior Member
    Join Date
    Oct 2012
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    2

    concurrent access to global memory

    I'm lost in this issue... maybe it's an trivial problem, but i've no clue to solve it.
    Btw. i'm new to OpenCL

    Code :
    kernel void Update(global float* MeasuredProjection, global float* CurrentVolume, global float* numinatorBuffer, global float* denominatorBuffer)
    //********
    // HERE IS SOME RayResampleStuff
    // If a Ray hits a Voxel the VoxelIndex will be stored in an Array called VoxelOffsetList
    //********
     
    for (int j= 0; j < HitCount; j++)
    {
     int UpdateOffset = VoxelOffsetList[j];
     
     numinatorBuffer[UpdateOffset] += d_value; //numinatorBuffer is 	a global float*								        
     denominatorBuffer[UpdateOffset] += 1; //denominatorBuffer is a global float*
    }

    Getting some sort of artefacts...

    Do i have to synchronize the access to the global buffers?
    Is there another way to solve this problem?

    Thanks in advance!

  2. #2
    Junior Member
    Join Date
    Oct 2012
    Posts
    2

    Re: concurrent access to global memory

    problem solved... i implemented an atomic_add for float but it's very slow!

    Any faster suggestions?

  3. #3
    Senior Member
    Join Date
    Aug 2011
    Posts
    271

    Re: concurrent access to global memory

    Quote Originally Posted by xMate23
    problem solved... i implemented an atomic_add for float but it's very slow!

    Any faster suggestions?
    Use an algorithm that doesn't require global sync?

    Unfortunately you don't give enough information to suggest more than that ...

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