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MarkIngramUK
Journeyman III

Slow kernel compilation speed (clBuildProgram) with Radeon 5700 XT (Navi)

Our application compiles OpenCL kernels at runtime, and we're discovering that customers with Navi based GPUs are suffering from extremely slow kernel compilation times (clBuildProgram).

The following are the first 5 kernels that we compile, taken from a log file. First NVIDIA, then AMD.

Compilation times with NVIDIA RTX 2080 SUPER installed (latest drivers, 461.40):

[OpenCL] 4149553730. Begin kernel compilation
[OpenCL] 4149553730. Kernel compiled in 170.4304ms
[OpenCL] 3026476454. Begin kernel compilation
[OpenCL] 3026476454. Kernel compiled in 176.2081ms
[OpenCL] 38168626. Begin kernel compilation
[OpenCL] 38168626. Kernel compiled in 175.3464ms
[OpenCL] 3157765234. Begin kernel compilation
[OpenCL] 3157765234. Kernel compiled in 154.0611ms
[OpenCL] 1764890686. Begin kernel compilation
[OpenCL] 1764890686. Kernel compiled in 176.8117ms

Compilation times with AMD Radeon RX 5700 XT (latest drivers, 21.2.2):

[OpenCL] 4149553730. Begin kernel compilation
[OpenCL] 4149553730. Kernel compiled in 1395.8775ms
[OpenCL] 3026476454. Begin kernel compilation
[OpenCL] 3026476454. Kernel compiled in 1322.6756ms
[OpenCL] 38168626. Begin kernel compilation
[OpenCL] 38168626. Kernel compiled in 1292.6209ms
[OpenCL] 3157765234. Begin kernel compilation
[OpenCL] 3157765234. Kernel compiled in 1306.0073ms
[OpenCL] 1764890686. Begin kernel compilation
[OpenCL] 1764890686. Kernel compiled in 1336.2341ms

As you can see, the AMD driver is compiling approx 10 times slower than NVIDIA's. I should also point out that non-Navi architecture GPUs don't seem to be affected.

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dipak
Staff
Staff

Re: Slow kernel compilation speed (clBuildProgram) with Radeon 5700 XT (Navi)

Hi @MarkIngramUK ,

Thank you for reporting it. I've moved the post to the OpenCL forum.  Also I've whitelisted you for the "AMD Devgurus" community.

Please provide a minimal reproducible test-case and attach the clinfo output.

 

Thanks.

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MarkIngramUK
Journeyman III

Re: Slow kernel compilation speed (clBuildProgram) with Radeon 5700 XT (Navi)

Minimal example available here - https://github.com/MarkIngramUK/ocl-compile-benchmark

Let me know if you need anything further.

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dipak
Staff
Staff

Re: Slow kernel compilation speed (clBuildProgram) with Radeon 5700 XT (Navi)

Thank you for providing the repro. We'll look into this and get back to you.