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Strange global memory bandwidth for HD 7970

Question asked by cadorino on Aug 23, 2012
Latest reply on Sep 4, 2012 by dmeiser

Hi to all,

I run the GlobalMemoryBandwidth sample on a AMD 7970 and the results is the following:

 

Platform 0 : Advanced Micro Devices, Inc.

Platform found : Advanced Micro Devices, Inc.

 

Selected Platform Vendor : Advanced Micro Devices, Inc.

Device 0 : Tahiti Device ID is 005EF838

Build Options are : -D DATATYPE=float4 -D OFFSET=16384

 

Global Memory Read

AccessType      : single

VectorElements  : 4

Bandwidth       : 1672.16 GB/s

 

Global Memory Read

AccessType      : linear

VectorElements  : 4

Bandwidth       : 1756.49 GB/s

 

Global Memory Read

AccessType      : linear(uncached)

VectorElements  : 4

Bandwidth       : 220.769 GB/s

 

Global Memory Write

AccessType      : linear

VectorElements  : 4

Bandwidth       : 501.668 GB/s

 

The question is: how can the linear read bandwidth be over 1 terabyte per second is the max theoretical bandwidth is about 260 GB/s?

The question that naturally follows is: are global buffer reads cached?

 

Thank you very much!

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