[Mesa-users] Technical issue: calculations going incredibly slow

[Amedeo Romagnolo]

Hi Warrick,

The evolutionary phase is completely random. The slowing down is uniquely
dependent on when I run it the first time on my pc.

ask these questions because I have two ideas.  First, you might be filling
> enough RAM that the various microphysics tables start using the hard drive
> page file, which could be slow.  If this might be the case, try adding
>
>      num_steps_for_garbage_collection = 1000 ! or something greater than
> default 0
>
> to the `&star_job` part of your inlist.
>

I checked it and it wasn't the problem. Even because I have a 50 GB RAM and
I would be very worried if MESA took so much space :)

My second (probably wrong) idea is that your CPU is overheating and the
> system is slowing it down.  I'm not sure about this because it isn't clear
> that rebooting would give it enough time to cool off.  There are many tools
> available but on Linux you can try [1]
>
>      cat /sys/class/thermal/thermal_zone*/temp
>
> for a quick look (output is in "millicelsius").  If this is getting to
> ~80-85°C, this might be your problem.
>

This is indeed a good hint. I mean, I don't know which thermal zones
represent, but some are indeed > 85 °C. And considering I have a HP Omen,
which is famous for overheating, this is surely something I need to
consider. What makes me wonder is how it is possible that only MESA is
slowed by the CPU overheating and not all the other processes. Is it
something possible?

Amedeo



On Tue, 4 May 2021 at 11:20, Warrick Ball <W.H.Ball at bham.ac.uk> wrote:

> Hi Amedeo,
>
> I haven't tried your inlists (thanks for attaching them!) but a few more
> details would help.  What phase of evolution is the star in when it starts
> slowing down?  If you reboot and run `./rn`, does it always start slowing
> down at the same timestep?  Or is it always after about 10 minutes, and not
> necessarily at the same timestep?
>
> I ask these questions because I have two ideas.  First, you might be
> filling enough RAM that the various microphysics tables start using the
> hard drive page file, which could be slow.  If this might be the case, try
> adding
>
>      num_steps_for_garbage_collection = 1000 ! or something greater than
> default 0
>
> to the `&star_job` part of your inlist.
>
> My second (probably wrong) idea is that your CPU is overheating and the
> system is slowing it down.  I'm not sure about this because it isn't clear
> that rebooting would give it enough time to cool off.  There are many tools
> available but on Linux you can try [1]
>
>      cat /sys/class/thermal/thermal_zone*/temp
>
> for a quick look (output is in "millicelsius").  If this is getting to
> ~80-85°C, this might be your problem.
>
> Cheers,
> Warrick
>
> [1] https://askubuntu.com/questions/15832/how-do-i-get-the-cpu-temperature
>
> ___________
>
> Warrick Ball
> Postdoc, School of Physics and Astronomy
> University of Birmingham, Edgbaston, Birmingham B15 2TT
> W.H.Ball at bham.ac.uk
> +44 (0)121 414 4552
>
> On Tue, 4 May 2021, mesa-users at lists.mesastar.org wrote:
>
> > Hi all,
> >
> > here is my problem. I have set a pretty vanilla simulation on MESA
> (inlists attached), but because of some weird black magic my calculations
> go fast enough over the first ten minutes, and then they dramatically slow
> down. And I'm not talking about
> > timesteps, but about the actual calculation time for each timestep.
> >
> > Even more weirdly, if I reset my PC and restart the simulations (./re)
> the code goes fast for another ~10 minutes and then slows again.
> >
> > I'm using Ubuntu 20.04, and I made sure no other process was running at
> the same time. And yes: I set the right number of cores.
> >
> > Did this happen to anyone else? Do you have any idea on how to solve
> this?
> >
> > Cheers,
> >
> > Amedeo
> >
> >
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