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ryta1203
Journeyman III

Increase GPR usage with new SDK and Driver?

I went from Catalyst 10.5 to 10.7 and SDK 2.1 to SDK 2.2 and now all my kernels have horrible performance and the register allocation is approximately DOUBLE!

What happened?

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38 Replies
ryta1203
Journeyman III

Increase GPR usage with new SDK and Driver?

BTW, has anyone else noticed this? Has it effected anyone else's performance? What am I missing here?

 

BlackScholes example has gone from 16 to 31 GPRs? Is this correct?

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ryta1203
Journeyman III

Increase GPR usage with new SDK and Driver?

Also, this problem seems to only be with the 5870?

For reported SKA GPR usage the 4870 is the same or better... ODD.

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Raistmer
Adept II

Increase GPR usage with new SDK and Driver?

Originally posted by: ryta1203

BTW, has anyone else noticed this? Has it effected anyone else's performance? What am I missing here?


My app has approx same performance under new Cat + SDK2.2.
On some workload it become slower ~2% on other even slightly faster.
Also, rebuild with new SDK had no effect on speed, old binary and new one execute with same speed under new SDK/driver.
But maybe my kernels just have no GPR pressure, didn't check what happened with GPRs via SKA.

EDIT: BTW, I use HD4870, so maybe my card didn't affected indeed...
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Curiouscat
Journeyman III

Increase GPR usage with new SDK and Driver?

I'm using the SKA in SDK 2.2 to check kernels written for SDK 2.1, targeting the 5870. It's a mixed bag. Some kernels are reported to have better throughput, some worse, and some which were reported to use 0 scratch registers now use several (I'm seeing 9, 11 and 15) and have reduced throughput.

Another problem:

#pragma OPENCL EXTENSION cl_amd_fp64 : enable

yields the following error:

error: can't enable all
          OpenCL extensions or unrecognized OpenCL extension

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ryta1203
Journeyman III

Increase GPR usage with new SDK and Driver?

Originally posted by: Raistmer
Originally posted by: ryta1203 BTW, has anyone else noticed this? Has it effected anyone else's performance? What am I missing here?
My app has approx same performance under new Cat + SDK2.2. On some workload it become slower ~2% on other even slightly faster. Also, rebuild with new SDK had no effect on speed, old binary and new one execute with same speed under new SDK/driver. But maybe my kernels just have no GPR pressure, didn't check what happened with GPRs via SKA. EDIT: BTW, I use HD4870, so maybe my card didn't affected indeed...


Yes, like I said, I'm not seeing a difference on the 4870 as far as GPR allocation is concerned (I haven't checked performance).

It's the 5870 (and probably the entire 58xx series) where  my GPR has increased dramatically in most kernels.

 EDIT: It's a concern for me since one of my kernels has gone from 31 GPR to 50 GPR. Simul wavefronts from 8 to 4, quite a difference in performance by using a "new" (and assumed "better") driver/SDK.

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Jawed
Adept II

Increase GPR usage with new SDK and Driver?

Are you using the update version of 10.7?

update driver

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Curiouscat
Journeyman III

Increase GPR usage with new SDK and Driver?

Originally posted by: Jawed Are you using the update version of 10.7?

update driver

Yes, I have all the latest and greatest installed. Even did a complete uninstall and directory delete followed by reinstallation to be sure. No change. I now have kernels which used to have 0 scratch registers using 9, 11, 15 and 20 scratch registers, and feel like Sisyphus.

It would be OK if performance improved by using more registers, but in all those cases it is reported to be down significantly.

Does

#pragma OPENCL EXTENSION cl_amd_fp64 : enable

work for you?

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genaganna
Journeyman III

Increase GPR usage with new SDK and Driver?

Originally posted by: Curious cat
Originally posted by: JawedDoes

 

#pragma OPENCL EXTENSION cl_amd_fp64 : enable

 

work for you?

 

Are you facing any problem with cl_amd_fp64 extension?

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Curiouscat
Journeyman III

Increase GPR usage with new SDK and Driver?

Originally posted by: genaganna Are you facing any problem with cl_amd_fp64 extension?

Yes, this:

OpenCL Compile Error: clBuildProgram failed (CL_BUILD_PROGRAM_FAILURE). Line 10: error: can't enable all OpenCL extensions or unrecognized OpenCL extension #pragma OPENCL EXTENSION cl_amd_fp64 : enable ^

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