On Thu, Feb 12, 2009 at 9:02 PM, Johansen.Klaus KYJ <[email protected]> wrote:

> 4)
> Is it possible to monitor the number of pages a guest has assigned to
> the "cmm1 page pool" at CP level? That is, the "dynamic guest size" seen
> from CP point of view (not proc/sys/vm/cmm_pages) - For example from
> Perfkit? (Unfortunately we don't have Velocity's performance products).

Sorry, my enter key fired too soon from pure thrill ;-)

It's very hard to fill in the blanks. As long as you drive the
cmm_pages from VM (which is imho the only place where you have
relevant metrics to provide the proper setting) you will have to
remember what you did. Though Leland referred to an APAR, I think it
was a change in the kernel that will make it let some air out of the
balloon when it finds things are a tight fit. So effectively this
should keep VMRM from choking your penguins. But it means that
remembering the setting will not do you much good.

It's not too hard to have a server with secondary console set up so
you can display the current setting though.

When Linux is swapping, then in theory you should be able to tell from
the resident page frames and paged-out frames how large the black hole
is (because Linux does not grow). Unfortunately, virtual machine pages
can be both resident and on paging DASD, so adding those up will not
help you. There's part of the virtual machine that does not cooperate
in this scheme, so you should be able to get some metrics by looking
at what happened earlier and how many pages were resident before you
paged it.

Rob
--
Rob van der Heij
Velocity Software
http://www.velocitysoftware.com/

----------------------------------------------------------------------
For LINUX-390 subscribe / signoff / archive access instructions,
send email to [email protected] with the message: INFO LINUX-390 or visit
http://www.marist.edu/htbin/wlvindex?LINUX-390

Reply via email to