device to device bandwidth calculation

Accelerated Computing CUDA CUDA Programming and Performance
#1

Hello

From the cudasdk2.2, bandwidthtest.cu example

in the testDeviceToDeviceTransfer() function, why is the bandwidthinMBs multiplied by a factor of 2.0 ?? Did i miss something ?

bandwidthInMBs = 2.0f * (1e3f * memSize * (float)MEMCOPY_ITERATIONS) /
(elapsedTimeInMs * (float)(1 << 20));

Thanks
-VA

#2

because you’re reading and writing.