[Mesa-users] Models with mesa_204.net do not attain the lgTmax value

[Farag, Ebraheem]

Hi Amar,

> Finally, I set "export OMP_NUM_THREADS=24"

Keep in mind that MESA doesn't scale well beyond 12 cores, you can see the Amdahl's law plots (Figure 47) in MESA III<https://ui.adsabs.harvard.edu/abs/2019ApJS..243...10P/abstract>. In my experience there is no benefit to using more than 16 cores, and in fact setting the number of threads higher can slow the code down. In your circumstance, with 8 efficiency cores, I'd probably set OMP_NUM_THREADS=16, as I would only want the p cores to be used (although mac os makes this choice for you).

Goodluck!

-EbF

________________________________
From: Amar Aryan <amararyan941 at gmail.com>
Sent: Monday, December 9, 2024 11:39 PM
To: Farag, Ebraheem <ebraheem.farag at yale.edu>
Cc: mesa-users <mesa-users at lists.mesastar.org>
Subject: Re: [Mesa-users] Models with mesa_204.net do not attain the lgTmax value

Hi Ebraheem,

Many thanks for your reply. It's never too late :-). In the meantime, I could get my models fully evolved up to the stage of the onset of core collapse utilizing the "approx21_cr60_plus_co56.net<http://approx21_cr60_plus_co56.net/>" network and with good temporal/spatial resolution.

For the whole run:
max_abs_rel_run_E_err = -1 ! default is unset, but it seems set to 1d-2 in your inlist.

For a given timestep:
limit_for_rel_error_in_energy_conservation = 1d-4 ! default
hard_limit_for_rel_error_in_energy_conservation = 1d-3  ! default

For my case, yes, max_abs_rel_run_E_err was 1d-2, although, I shall use  '-1' in my new run. I had limit_for_rel_error_in_energy_conservation = 1d-7 and  hard_limit_for_rel_error_in_energy_conservation = 1d-6 in inlist_common. Also, these were set to limit_for_rel_error_in_energy_conservation = 1d-3 and  hard_limit_for_rel_error_in_energy_conservation = 1d-2 in later inlists (inlist_to_lgTmax and inlist_to_cc) for the models which failed (I still use these values in my new run).

The stopping conditions that I use in inlist_to_lgTmax is: log_max_temp_upper_limit = 9.600d0

Thanks for your suggestions regarding op_split_burn_minT. Earlier it was set to 2.5, now I decreased it to 1.5.

Finally, I set "export OMP_NUM_THREADS=24". (Our Studio has 24 (16 performance + 8 efficiency) cores)
With the above changes employed, I start the run again with only one model running on our STudio. I shall keep you updated with the results. Thank you again for your time in looking at such an old query!

With best regards,
Amar
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