"An RTOS (Real-time Operating System) will sacrifice performance to achieve determinism (low latencies). Several key features to an RT system usually come with a performance cost. A non RT system will perform 99% of the time faster than an RTOS. But all it takes is that one time to miss a deadline to make an RT system crash.

"This is the largest performance improvement to hit the RT patch since the removal of the global PI lock. On my 4way box running 'hackbench 50' went from 18 seconds down to just under 5 seconds (4.8). Vanilla 2.6.24.7 on this same box runs at 3.9 secs. This is the first time that the RT patched kernel is less than a magnitude away from mainline running this hackbench test."

"I thought that one could place a printk anywhere without worrying. But it seems that it is not wise to place a printk where the runqueue lock is held."