CPU usage hits 100% during FIFO read

Question

I have a real time PC with a 7833R RIO board. I write values which I read from a microphone into a FIFO at a sampling rate of 4 kHz.The length of the FIFO is 2048. On the real time PC, when I call "FIFO read" function to read say 400 samples of data, the CPU utilization of the real time PC hits 100%. Why is this so? The "FIFO read" function is placed inside a while loop.
Thanks
Prashant
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Answer 1

Hello Prashant,
Jaared had given good link to work on.. I suggest about time syncronisation on FIFO read and write..
Consider following case:
B is the data written to the FIFO at F1 frequency and read at F2 frequency
then, time taken to write to the FIFO = B/F1 ;
data read from the FIFO in this time=(B/F1)* F2;
If F1>F2 (write freq>read freq)
The Excess data remained unread = B- (B/F1)* F2;
If F2>F1 (read freq>write freq)
The lack of data for syncronisation = (B/F1)* F2 -B;
The above can help you in designing of synchronised FIFO
Apart from that please use time out also based on above calculation with time
BR, HS