Going to buy a new pc...

Giorgio De Nunzio

Nov 21, 2000

Hi all!
Unhappily a lot of work and family tasks have forbidden me to participate
to all the recent interesting discussions about Hercules, VS1, MVS3.8.
I hope to have some more time in the near future.

Now, the questions:
I am going to buy a new pc; I don't want to pay it too much, so I am going
to take a Pentium III 800MHz, with 384 or 512MB RAM.
I'd like to know some performance figures of the current Hercules version
with the currently working OSes: some of them can be used by now, some are
likely to be usable in the future, so I'd like some MIPS figures for 370
mode (e.g. OS/360, MVS 3.8) and 390 mode (e.g. OS/390).
Is there someone with a similar configuration (800MHz, 512MB RAM) that can
give me some info?

Another question: what is the exact influence of the RAM quantity devoted
to Hercules, on the emulated OS performance? Is it worth while using a lot
of RAM (512 MB, say, or more) or is there a limit which is useless to pass?

Thanks and good work!

Giorgio

10:46 am

Re: Going to buy a new pc...

Jay Maynard

Nov 21, 2000

On Tue, Nov 21, 2000 at 10:46:42AM -0100, Giorgio De Nunzio wrote:
> I'd like to know some performance figures of the current Hercules version
> with the currently working OSes: some of them can be used by now, some are
> likely to be usable in the future, so I'd like some MIPS figures for 370
> mode (e.g. OS/360, MVS 3.8) and 390 mode (e.g. OS/390).

You'll probably get about 2.5 to 3 MIPS out of that box, lower with heavy
I/O. That goes for either mode. The PIII-800 uses the Coppermine core, so
you'll see real performance gains over a previous version.

> Another question: what is the exact influence of the RAM quantity devoted
> to Hercules, on the emulated OS performance? Is it worth while using a lot
> of RAM (512 MB, say, or more) or is there a limit which is useless to pass?

370-mode OSes can't use more than 16 MB (well, MVS/SP can use up to 64 MB).
OS/390 can use all you can throw at it up to 2 GB, and will make use of
expanded storage as well. You're not going to be running the kind of
workload that will use that much RAM, though. As cheap as RAM is, you can
probably afford to buy a bunch of it, and having more makes Linux run
better, which in turn will make Hercules run better.

In general, I'd recommend giving hercules-390 up to 256 MB, while leaving 64
to 128 MB for Linux. On my 192 MB laptop, I'd experiment with giving
Hercules between 64 and 128 MB, leaning toward the lower end for older
OS/390s and higher for newer ones. On your 384 MB machine, 256 for Hercules
would still leave 128 for Linux, which is likely under any kind of workload
you're likely to generate to minimize or eliminate both S/390 and Linux
paging. Buying the extra 128 MB of memory for Linux would allow you to do
other things on your box while Hercules is up more easily, and may save you
a DIMM slot as well (two 256 MB DIMMs instead of three 128s). DIMM slots are
very expensive when you use them all up, as you usually wind up removing
DIMMs to upgrade.

1:24 pm

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