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[broxvall]

Currently only 256MB of memory can be used on all cards?

Hi,

I've recently noticed that not all GPU memory can be used from OpenCL on my 5870, regardless of it they are allocated in one or multiple chunks.

From browsing some older threads from 2009 I saw a comment that this is likely due to a limitation from the underying CAL which restricts us to 256MB sized chunks. And that all memory cannot be used, even if multiple buffer objects have been allocated.

Could someone in the know confirm that this is still supposed to hold in the latest drivers? What are the plans for future releases, does this feature have a priority to be fixed (ie. is it worth waiting a few months?) or is it belived to take longer before all memory can be used?

Are there any tricks of circumventing this? (i've managed to allocate slighty more memory - but not much - by using multiple buffer objects)

Many thanks for any information on this=)

[bubu]

Yep it's a pain not to be able to allocate all the VRAM you need...

See this:

http://forums.amd.com/devforum/messageview.cfm?catid=390&threadid=129209&enterthread=y

[broxvall]

Thanks, this was very usefull and will hopefully save me some swapping back and forth between CPU and GPU memory as part of the computations.

[Raistmer]

Situation with available memory still unclear.
On some hosts even with SDK2.1 installed corresponding enc variable should be added to get past 128MB limit, on anothers - no additional modification after SDK install were required.
Limited user base (to require from user to install development SDK not good way to increase user base!) not allows to find some correlations (all for HD4xxx, HD5xxx have no 128MB restriction).

[bubu]

I use the SDK 2.1 with Windows 7 x64 and Cat 10.5 with a Radeon 5750(512Mb)  and I wasn't able to allocate two 128Mb buffers.

I placed the environment variable called GPU_MAX_HEAP_SIZE to 512 and now I can so...

About the idea to limit the buffers to 128Mb is a terrible bad idea for the motives I exposed in that other post ( PS 256Mb + 3dsmax 192Mb, both will fail, unlimiting the memory=both will run with 512Mb ).

Pls, ATI, we need that 128Mb limit removed.

[Raistmer]

yes, it was very bad idea indeed suitable, maybe, for some preview/beta version, but not for SDK release version ATI claims to have starting with 2.0 and still not meeting release qualification with 2.1 btw...
If I would need only 128 MB I would not spend money for 512 MB card.

[omkaranathan]

Raistmer,

We are working to get this limit removed.