[Users] Inconsistency warnings: cores/threads mismatch [Leonardo cluster]

[IOSIF PANAGIOTIS]

Hi Roland,

Thanks for your reply.
You touch on an important point, i.e the cluster's billing policy, that hadn't crossed my mind.

>From the billing policy of Leonardo, it seems that it is possible to use only a fraction of a node's total CPUs.
https://docs.hpc.cineca.it/hpc/hpc_intro.html#billing-policy

However, the documentation also stresses that:
...if a job reserves all of a node’s RAM — even without utilizing all its CPUs — the node becomes unusable for other jobs and is therefore billed accordingly.

So, apart from the cores requested, should I also try to calculate the RAM requirements?
For example, I see that Bruno's "leonardo-dcgp.ini" file specifies:
memory = 494000
And the respective submitscript also has this line:
#SBATCH --mem 494000MB

I note that each node in Leonardo has 512GB of RAM, so that means that the script requests ~94.2% of the RAM.
I am not sure I follow the reasoning behind this.

What is the default behavior of SimFactory if I were to remove the above specifications from the config files?
Because, if by default Simfactory requests/uses all the RAM available in a node, then as far as I understand, it does not make sense to request fewer cores than a full node.
Let me know what you think.

Best,
Panayotis


________________________________
From: Roland Haas <rhaas at mail.ubc.ca>
Sent: Friday, September 26, 2025 4:31 PM
To: Bruno Giacomazzo <bruno.giacomazzo at unimib.it>
Cc: IOSIF PANAGIOTIS <PANAGIOTIS.IOSIF at units.it>; Einstein Toolkit Users <users at einsteintoolkit.org>
Subject: Re: [Users] Inconsistency warnings: cores/threads mismatch [Leonardo cluster]

Hello all,

> I never used --cores and I don't know the difference with procs.

--cores is a synonym for --procs in simfactory. The hope was to avoid
the confusion of "procs" being "Processes" or "Processors". Though it
has been pointed out that the best name would actually be "--threads"
since that is what simfactory actually starts, which then collides with
"--num-threads" (threads per process).

Does Leonardo actually charge you for partial nodes if you do no use a
full one? Simfactory is mostly written under the assumption (true at
the time) that HPC systems would give you full nodes all the time, so
if you use 1 core or 112 cores of a node, the charge would be the same
(though shared node systems are becoming more common for HPC now [or
again]).

Yours,
Roland

--
My email is as private as my paper mail. I therefore support encrypting
and signing email messages. Get my PGP key from http://pgp.mit.edu .
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.einsteintoolkit.org/pipermail/users/attachments/20250929/9d785692/attachment.htm>