Raistmer

LDS banks on HD5870

Discussion created by Raistmer on Oct 7, 2010
Latest reply on Oct 7, 2010 by Raistmer
From manual:
"
All AMD Evergreen GPUs contain a 32K LDS for each compute unit. On high-
end GPUs, the LDS contains 32-banks, each bank is four bytes long
"
If each bank contains 4 bytes and there are 32 banks, where other 32*1024-32*4 bytes of LDS are located ??

And later:
"
Note that a sequential access pattern, where each work-item reads a float4 value
from LDS, uses only half the banks on each cycle on the ATI Radeontm HD 5870
GPU and delivers half the performance of the float2 access pattern
"
How it could be?
0x00-0x03 go to bank1, 0x03-0x07 to bank2 and so on, right? that is, 16(quater-wavefront)*4(float4)*4(bytes per float)=256 bytes read and should cover each bank 2 times more than float2 accesses, no?

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