Switch to the 4BSD scheduler for RELENG_5

[josef]

Aufgrund von noch immer nicht geloesten Stabilitaetsproblemen in manchen Bereichen,
wurde der umstrittene Scheduler ULE durch den bisherigen 4BSD wieder ersetzt.

[scott long auf current]

In the interest of getting RELENG_5 stable and ready for 5.3, we are
going to switch the scheduler in 6-CURRENT from SCHED_ULE to SCHED_4BSD.
Tests are showing that the 4BSD is a bit more stable under load than
ULE, and is a LOT morestable than ULE with PREEMPTION enabled. This
does not mean that ULE is being removed or that we have lost confidence
in the direction and features of ULE. By changing this we can focus on
stability for the rest of the RELENG_5 cycle. I'd encourage anyone who
is interested in the ULE scheduler to talk to Julian Elischer and Jeff
Roberson about what needs to be done with it. Once 5.3 is released we
can look at switching 6-CURRENT back to ULE if it makes sense.

 

[I.MC]

? Was hat der Scheduler in CURRENT mit RELENG_5 zu tun :-)

Gruß, I.MC

 

[Maledictus]

Die Frage kam auch prompt auf der Liste, hier die Antwort von Scott Long:

We are trying to keep HEAD as a good test-bed for future RELENG_5 fixes.
It's hard to get broad testing of scheduler related things if HEAD and
RELENG_5 are using different schedulers. We also want to see HEAD be
stable enough to develop and test non-scheduler related things too.