real time linux probelm

Hi All,
I have a board contains ARM processor shipped with Linux kernel 2.6.21.
I have applied real time patch to the kernel namely

linux-2.6.21-rt8

i run the application again on the board to test the performance but i have noted some strange behaviors:
1. the application seems to be hanged, it seems to get into infinite loop but when i press any character on minicom, the printfs are out to STDOUT. i thought it was a problem in buffering the printf, i have forced it to be unbuffered but it make no difference.

2. as for the timers, when i use gettimeofday on the normal linux kernel (non real time), for 2 consecutive lines, i got different ouptuts in the field of tv_usec but after using the real-time patch
i found that the result of gettimeofday for 2 consecutive lines are exact the same.

can anyone help me or can guess what is the problem?

thanks

Hi.
Can you elaborate more about your steps after you applied your real time patch?. I guess you are using RT_PREEMPT real time patch. I would like to know that your board vendor ensure that your real time patch already tested for this board?. Provide your ARM processor details also.