Re: PMR54458 - ever increasing % tep addresses

[Simon Coulter <shc@xxxxxxxxxxxxxxxxx>]

On Wednesday, February 4, 2004, at 08:19  PM, McCallion, Martin wrote:

> I thought the temporary addresses were cleared at IPL and the permanent
> ones were not.  However, don't forget we're talking about a 64-bit
> address space; doesn't that mean there are more addresses available 
> than
> the number of atoms in the Universe, or something?

Temporary addresses are cleared during an IPL but the system uses some 
of them for internal objects during the IPL so it will never be zero.

The 64-bit address space is chopped into quarters: 25% for temporary 
objects, 25% for permanent objects whose virtual address matches the 
real address, 25% for other permanent objects, and 25% not used. This 
reduces the actual address space quite a bit but not enough to worry 
about.

If temporary addresses are being consumed quickly it usually indicates 
an application problem (but might be caused by a defect in a licensed 
program such as SQL).

> > OK, I admit, the rate we are using the % temp addressis is
> > around 0.5%/month
> > and before anything serious can occur, we are likely to
> > upgrade the OS
>
> So (if that rate of growth remains constant) it would take 200 months 
> to
> go from zero to 100%; that's over sixteen years.  You'll have upgraded
> the _hardware_ long before that, never mind the OS.  Though I speak as
> one looking at a development partition which is currently showing % 
> perm
> addresses 0.018 and % temp addresses 0.042, so it's easy to be
> complacent.

It's a bit like being worried by the fact that the IPL count forms part 
of an objects address. The count is a 2-byte number so allows for 65535 
IPLs which at 1 per day means you would have a problem in 179 years.

Regards,
Simon Coulter.
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