Updating number of CPUs in UM7.3 for ACCESS-ESM1.5

Earth System
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Hi,
I am looking to update some older runs using ACCESS-ESM1.5 that are currently running with 384 CPUs. I understand the new releases are using 432 CPUS, with the UM changing from 192 CPUs to 240 CPUs. I would like to update my old settings to take advantage of this optimisation… just wanted to check if you don’t mind, which input settings I should pay attention to?

I’m guessing the settings in atmosphere/namelists and config.yaml are the key places, but is there anything else I should look for?

help

Thanks, Dave

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… Just poked around and saw that in um_env.yaml there are the following fields (in my older version):

UM_ATM_NPROCX: '16'
UM_ATM_NPROCY: '12'
UM_NPES: '192'

And that in the new release, these are updated to:

UM_ATM_NPROCX: '16'
UM_ATM_NPROCY: '15'
UM_NPES: '240'

Is there anywhere else I need to specify this change, other than config.yaml?

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Hey,

I’ve discussed already with Spencer about updating ESM1.5 with these changes and making a new release.

I know I’ve asked this before, but could you make a topic on the forum and ask this question (or you can make the message into a topic). It’s good when people ask for stuff and we can say YES!, and it helps to bump up the priorities, and others can also chime in if they need it too.

Thanks!

Edit: for clarity/correction

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I’m confused… this is a topic on the forum.

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So sorry. Yes you are correct. Oops!

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Hi @dkhutch, that’s correct! The only changes needed should be the the ones you’ve listed in the config.yaml and um_env.yaml.

Cheers,
Spencer

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Awesome, thanks for confirming Spencer!

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@gpontes @HIMADRI_SAINI @BenjaminAnthonisz
Just to update people I know who are still running ACCESS-ESM with 384 CPUs:
If you update these settings in um_env.yaml and also update the CPUs in config.yaml to 240 CPUs, then the whole thing runs significantly faster. This is a feature of the new releases…

To give you some numbers, my runtimes have decreased from a typical 1:15 to 1:05, and the typical service units have actually decreased from around 970 SUs per year to ~930 SUs per year. So the model runs faster and costs less KSU…

4 Likes
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All thanks to @spencerwong.

Does this lead to different answers @spencerwong? I can’t recall.

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The processor change didn’t change answers (I think for ~20 years) with the preindustrial configuration when we made the change. However, @manodeep has since found a couple of examples where the UM’s layout did change answers some time into the run, and so it’s hard to be certain especially in long runs.

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