ARM-core bandwidth

[Nader_Jendoubi]

Hi

i used the epiphany example e-bandwidth-test to transfer a 4KB data between arm and epiphany and DRAM and i get the following
results:

ARM Host --> eCore(0,0) write spead = 12.44 MB/s
ARM Host --> eCore(0,0) read spead = 6.24 MB/s
ARM Host --> ERAM write speed = 75.20 MB/s
ARM Host <-- ERAM read speed = 102.63 MB/s
ARM Host <-> DRAM: Copy speed = 190.92 MB/s
eCore (0,0) --> eCore(1,0) write speed (DMA) = 1182.52 MB/s
eCore (0,0 --> eCore(1,0) read speed (DMA) = 377.11 MB/s
eCore (0,0) --> ERAM write speed (DMA) = 237.90 MB/s
eCore (0,0) <-- ERAM read speed (DMA) = 85.77 MB/s

i wanna ask why the arm-ecore speed is much slower than arm-eram or arm-dram or ecore-eram speed. Can anyone explain to me the reasons of these differences referring to the parallella architecture

Thanks