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Thread: Can different kernels run in a single Compute Unit simultaneously?

  1. #1
    Newbie kuba15's Avatar
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    Can different kernels run in a single Compute Unit simultaneously?

    I'm puzzled about Wavefront after reading some materials.
    I have two questions that confuse me.
    (1) If there are 4-way SIMDs(16-lane) in a single compute unit and more than 64 work-items running within the compute unit, will the wave scheduler launch all the work-items on all of the four SIMDs or just on one SIMD? In this way, do we call the wavefront with the length of 16 or 64?
    (2) If there are 2 kernels running on a GPU, will the threads owned by different kernels(in different command queue) run in the same compute units simultaneously?

    Sincerely for your help!!!

  2. #2
    Senior Member
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    Quote Originally Posted by kuba15 View Post
    I'm puzzled about Wavefront after reading some materials.
    I have two questions that confuse me.
    (1) If there are 4-way SIMDs(16-lane) in a single compute unit and more than 64 work-items running within the compute unit, will the wave scheduler launch all the work-items on all of the four SIMDs or just on one SIMD? In this way, do we call the wavefront with the length of 16 or 64?
    (2) If there are 2 kernels running on a GPU, will the threads owned by different kernels(in different command queue) run in the same compute units simultaneously?

    Sincerely for your help!!!
    Keep in mind that this is only relevant for AMD GPUs. I believe, a unit of scheduling there is a full wavefront (64 workitems). I cannot answer your second question with certainty though.

  3. #3
    Junior Member
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    As far as I know, only one wavefront can be scheduled at one time and one wavefront does only contain work items of one kernel.
    Which means the answer to the second question is "No".

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