[Mesa-users] Same models on a recent MESA release runs much slower than on an old one

[Lorenzo Martinelli]

Dear MESA Users,

I’m porting to the recent MESA r23.05.1 (and lately r24.03.1) some of the inputs and custom subroutines in the run_star_extras used for computing large grids of models with an old release MESA r11701.
I’ve been successful in porting all the features, the models run, behave and and look as expected. However I noticed that especially for models that develop strongly degenerate helium cores after the main sequence, roughly below 2.0 solar masses, the new models were running significantly slower.
After making sure that none of the custom subroutines and inputs were the cause of this slowness of the models in the latest version, I copied the default /mesa-r23.05.1/star/work and just change the initial mass to 1.7 solar masses. I did the same for MESA r11701, run both of them and compared the runtime.

I found that even with all default settings, the most recent one was running much slower (on the MS it is not very noticeable, but it starts to be evident on the RGB), with a difference of several hours (a big deal when you have to run a grid).

I attach here the inlists that I used for these tests, which I just replaced inside copies of the /mesa-r23.05.1/star/work and /mesa-r11701/star/work respectively.

I’m using the appropriate MESA SDK for each different MESA release and I’m running them on the same MacBook Pro Quad-Core Intel Core i7, I even tried to run the MESA r23.05.1 also on a new MacBook with M3 chip (8 cores) and it’s still slower than the old MESA r11701 on the Quad-Core Intel Core i7.

Does someone have an idea why the models with the more recent MESA release runs slower even with the defaults settings? Is there something that I can do to recover that speed (which is quite critical considered the number of models that I need to compute)?
Thank you!

Kind regards,

Lorenzo Martinelli
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