mvme5500: data transfer rate to and from vme space

rwas rbtwas at
Tue Oct 23 19:37:42 UTC 2012


I've done some timing measurements on block transfers of data from the 
vme space to
local memory space. My effective transfer rate is about 2mbytes/sec. In 
theory, the vme
backplane can handle about 20mbytes/sec. I've checked this for various 
block sizes and
the transfer rate scales roughly proportionally with size.

word size: 32bit (transfers are 32bits at a time)
block size: 256bytes: 150uS
block size: 1040bytes: 530uS
block size: 3032byes: ~1.2mS

addr space: 32bit

rtems: 4.9.3

Help appreciated.

Robert W.

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