why did Ubuntu turn off kernel preemption in Edgy?

[Ivan Krstić]

Ben Collins wrote:
> It was a few of those very hackers that told me PREEMPT was a red
> herring, and 1000HZ was not suggested. 

That sounds about right. A bit of history is in order here: voluntary
preemption was introduced in 2.6 precisely because the standard PREEMPT
was causing latencies of up to 50ms under a stronger load. By abusing
might_sleep() and treating it as a scheduler yield, the initial
voluntary preemption patch returned the 2.6 kernel to the real-time
performance of 2.4 with the lowlatency patchset (<1ms latencies), with
the audio crowd in mind as one of the target user groups.

-- 
Ivan Krstić <krstic at solarsail.hcs.harvard.edu> | GPG: 0x147C722D