On 2/2/06, Stefan Raabe <[EMAIL PROTECTED]> wrote:
>
> > Locking pages for performance is normally a Very Bad Idea (TM). Don't
>  > do that. If you really want, you could steer CP a bit with SET
>  > RESERVED but you probably need to look at other options.
>
> vm has 2gb storage, there is only one linux guest with 1gb storage defined, 
> no other guests
> (except some system stuff like tcpip etc. and some administration users).

That's a pretty uncommon situation with your z/VM real memory larger
than the total virtual memory.

> before i locked the pages of the linux guest i saw paging rates between 200 
> and 800 per
> second, mdc size was about 1.2gb (if i remember right).
> my first action was to reduce mdc to 600mb, which reduced paging, but vm 
> still paged out
> some pages of the linux guest so i still had some paging when the linux was 
> busy.

I am surprised to see you got so much data eligable for MDC. If that
is due to Linux reading a lot of data then MDC is probably wasted
there, and you could consider to disabled MDC for those disks in
addition to setting the maximum to the point where you like it.

> I thought this was a "very good" setup when you only have to serve one guest 
> to serve,
> and not a "very bad" one?!?

Upto z/VM 5.2, most installations with Linux on z/VM are constrained
under the 2G. Locking pages (or anything that lives under the bar) is
making things worse. You're an exceptional case since you're not
constrained and you have all under the bar.

Rob (happy I did include "normally" with my Bad Idea)
--
Rob van der Heij                  rvdheij @ gmail.com
Velocity Software, Inc

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