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bandwidth of different clImage format and efficient access pattern

chris_pn
Beginner
1,030 Views

Hi,

    Per OpenCL Developer Guide (as shown below), I find that max bandwidth of each sampler is 64 Byte/cyc:

https://software.intel.com/content/www/us/en/develop/documentation/iocl-opg/top/coding-for-the-intel...

    My questions are:

1. Which clImage format with (efficient access pattern) can achieve max bandwidth?

2. Does different clImage format has a max texel/cyc when read by sampler? If yes, where can I find the data for common-used format?

3. What's efficient access pattern to read clImage by Sampler?

    Thanks!

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1 Solution
Dunni_A_Intel
Moderator
773 Views

Hi Chris,


Apologies for the delay in providing you with a timely response.


  1. The maximum bandwidth may only be achieved when all accesses hit the cache. In general, accesses to smaller image formats will yield better performance than accesses to larger image formats.
  2. Yes, performance varies with different image formats. However, I am unable to locate any public documents with specific performance numbers.
  3. 2D accesses patterns will be efficient based on how images are actually laid out in memory.


Please let me know if this answers your questions and if you have any additional questions.



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7 Replies
VidyalathaB_Intel
Moderator
1,004 Views

Hi Chris,

Thanks for reaching out to us

we are working on your issue. we will get back to you soon

Regards,

Vidya


chris_pn
Beginner
989 Views

Thanks Vidya. For clImage write operation, I also has the same question. So many thanks If you could also provide answer for clImage write operation. Thanks again!

chris_pn
Beginner
922 Views

Hi Vidya,

    Can you answer my questions now or could you tell me how long should I wait for the answer? Thanks.

chris_pn
Beginner
872 Views

Hi Vidya,

    Do you have any update? I'm looking forward to your answer. Thanks!

Dunni_A_Intel
Moderator
774 Views

Hi Chris,


Apologies for the delay in providing you with a timely response.


  1. The maximum bandwidth may only be achieved when all accesses hit the cache. In general, accesses to smaller image formats will yield better performance than accesses to larger image formats.
  2. Yes, performance varies with different image formats. However, I am unable to locate any public documents with specific performance numbers.
  3. 2D accesses patterns will be efficient based on how images are actually laid out in memory.


Please let me know if this answers your questions and if you have any additional questions.



chris_pn
Beginner
729 Views

Hi Dunni,

    Thanks for your answer. It can be better if there is detailed explaination and samples. Current answer related to clImage provided by Intel official document is too short and rough to understand. Image is also a important memory object of OpenCL for user. Thanks anyway.

Dunni_A_Intel
Moderator
751 Views

Hi Chris,


We will no longer be monitoring this thread. Please feel free to make a new post if you have additional questions.


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