Re: [Gems-users] Checkpoints

[Derek Hower <drh5@xxxxxxxxxxx>]

> 1. I assume there is no difference between sarek and abisko from GEMS point
> of view. I mean we can use both. Is that right?

Correct.

> 2. Since number of processors and memory are the main inputs to the script,
> I started with them. As far as I know, number of cpus is not hot-pluggable
> so you cannot change the number of processors after you boot a machine. Is
> this the case for memory as well?

I don't believe the memory is hot-pluggable, but to be honest I'm not
100% sure.  You should check that out in the Simics forums.

> 3. I checked the target guide for serengeti and accordingly, I set the
> following parameters in abisko-common.simics
>     - $os
>     - $num_cpus
> $disk_size was same with the one used in the script so I left it as it is.
> However, I do not know how to setup disk_{cylinders,heads,tracks} which were
> set to some numbers in the script, as I couldn't see any match in the guide.
> Any ideas on this?

Again, try the Simics forum.

> 4. Same question for memory, it looks like the second parameter represents
> the entire memory. How can I specify that in the abisko-common.simics? I
> only see $megs_per_cpu, so let's say for a 16 processor machine should I
> basically divide that to 16 and set it for $megs_per_cpu? Would that be
> consistent with what Ruby is looking for?
>

Yes, but be careful.  I'm not familiar with the abisko machine, but
depending on how memory is laid out you may end up with a
non-contiguous address space.  Ruby handles non-contiguous addresses
correctly, but may take a major performance hit.  From the GEMS
perspective, you are usually better off trying to arrange memory in a
top heavy fashion (e.g. as much as you can on board 1, then the rest
on board two, none on boards 3, 4, 5, ...)

> Am I missing anything to start my runs with GEMS? Sorry for the long e-mail
> and I also apologize if I am trying to ask anything obvious.
>
> Any help is appreciated.
>
> Regards,
>
> /edwl
>
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