ULE Scheduler available in 5.3-RELEASE?

[Mark Magiera]

> Brooks Davis wrote:
>
>>On Thu, Nov 11, 2004 at 09:29:08AM -0600, Thomas T. Veldhouse wrote:
>>
>>
>>>I just read in the release notes that 5.3-RELEASE has the new ULE
>>>scheduler available, but that 4BSD is the default scheduler.  I thought
>>>I read messages in freebsd-current indicating that the option to use ULE
>>>was completely removed from the 5.3 or even the RELENG_5 branch?  So, is
>>>ULE really available?
>>>
>>>
>>
>>ULE is not available in 5.3 or RELENG_5 due to problems that were
>>unfixed at the time of the release.
>>
>>-- Brooks
>>
>>
>>
> Perhaps the release notes should be updated?
>
> Here is a quote
> (http://www.freebsd.org/releases/5.3R/relnotes-i386.html#NEW):
>
> "The ULE scheduler has been added as an additional scheduler. Note that
> the conventional one, which is called 4BSD, is still used as the default
> scheduler in the GENERIC kernel. For the average user, interactivity is
> reported to be better in many cases. This means less ``skipping'' and
> ``jerking'' in interactive applications while the machine is very busy.
> This will not prevent problems due to overloaded disk subsystems, but it
> does help with overloaded CPUs. On SMP machines, ULE has per-CPU run
> queues which allow for CPU affinity, CPU binding, and advanced
> HyperThreading support, as well as providing a framework for more
> optimizations in the future. As fine-grained kernel locking continues,
> the scheduler will be able to make more efficient use of the available
> parallel resources."
>
> Thanks in advance.
>
> --
> Thomas T. Veldhouse
> Key Fingerprint: 07C7 BF05 4176 F50B A083  4542 0118 1315 761F D300
> Spammers please contact me at renegade at veldy.net.
>
I beleive the errata document takes precedance over the release notes. In
which case...
(http://www.freebsd.org/releases/5.3R/errata.html#OPEN-ISSUES)
"(1 Nov 2004) The ULE scheduler described in the release notes has been
completely disabled to discourage its use because it has stability
problems."

-- Mark Magiera