Subject: Re: UBC performance/tuning "issues"
To: None <>
From: Christos Zoulas <>
List: tech-perform
Date: 06/19/2002 22:07:23
In article <>,
Perry E. Metzger <> wrote:
>Martin Weber <> writes:
>> Really, I have to agree with Wojciech, a hint or howto pointing out all
>> the knobs, as well as reasonable values for those, would be rather helpful
>> for the gros of the NetBSD users imho. That is not to say that the defaults
>> are unusable, just saying that it would make research on how to tune your
>> system to your needs easier.
>There should be a man page for this. I'll get one done.
>In general, though, UBC is pretty easy to tune. If you're spending all
>your time paging in executables, raise execmin until you feel your
>performance is happy. If you are paging anons in constantly, raise
>anonmin until that one is happy. The goal is to get your paging rate
>down as far as you can go without sacrificing the benefits of the
>larger buffer cache. It depends a lot on your system load and mix. On
>a system that does mostly giant builds and has gigs of memory, making
>75% of memory or even more into buffer cache is a quite reasonable
>idea. On a system with 32M, tuning is necessarily different.
>Usually I advise people on small memory machines to just kick up the
>exec and anon parameters bit by bit until they feel like they have
>interactive performance on par with what they want.

Well, the kernel could be intelligent enough to adjust the parameters
itself by keeping usage statistics.