when i have a low priority process running on my P4 3.4GHz system which does sync() system-calls, my interrupt+scheduling latency jumps up to 400 microseconds.
This behavior is reproducible! To generate the sync() load i start "stress --io 2 " from weather.ou.edu/~apw/projects/stress
When i check the system with other tests, like sqrt() oder malloc() the latency is 25 microseconds (worst case). I tried with DMA enabled and disabled.
Is it possible that QNX can’t handle sync() calls properly?