SchedULE vs BSD scheduler - Was: HP ProLiant DL360 G5 success stories?

[Jeff Roberson]

On Sat, 15 Mar 2008, Rong-en Fan wrote:

> On Sat, Mar 15, 2008 at 12:14 AM, Christopher Sean Hilton
> <chris at vindaloo.com> wrote:
>>
>>  On Mar 12, 2008, at 12:05 PM, Oliver Fromme wrote:
>>
>> >
>> > Those machines work very well with both FreeBSD 6 and 7.
>> > If you install FreeBSD 7, remember to enable ULE instead
>> > of the default BSD scheduler.
>> >
>>
>>  What's the advantage of ULE / disadvantage of the default? Is it
>>  specific to this hardware?
>
> It gives you better performance. You may want to check Kris's slides
>
> http://people.freebsd.org/~kris/scaling/7.0%20and%20beyond.pdf

We have found a couple of small performance problems since 7.0 in ULE that 
will be addressed for 7.1.  ULE in CURRENT has already diverged too 
seriously to backport entirely.

In general you'll get better performance for things like databases, 
network servers, etc.  However, you may not get better performance for 
buildworld/kernel, or user-space heavy computationally intensive 
things like setiathome.

Since the fixes that are going into 7.1 (not yet in RELENG_7), I do not 
believe we've found a workload where 4BSD outperforms ULE by more than a 
couple of percent if that.  And there are many where ULE wins by over 
30%.

It was not made default for 7.0 because the stability came too late.  It 
ended up being plenty stable so we recommend users try it now.  We just 
didn't have enough experience with it at the time.

Thanks,
Jeff

>
> Regards,
> Rong-En Fan
>
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