fifo-dma, memset. good test or not?

My prototypesystem uses a dma to fetch data from a fifo to my SDRAM.

i want to test that the cpu has the time to play around with the data between each read from fifo without the fifo overflowing.

this is my testloop:

while(1){

alt_dma_rxchan_prepare(rxbuf,.....);

if(altera_avalon_fifo_read_level > testlimit){

printf("altera_avalon_fifo_read_level")

}

memset(rxbuf,...);

memset(rxbuf,...);

memset(rxbuf,...);

memset(rxbuf,...);

memset(rxbuf,...);

}

my test runs nice, but can i conclude that the CPU and SDRAM are kept busy during the memset's? what i about is that the compiler might optimize away all memsets but the last.

Thanks