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

[RICHARD H D TOWNSEND]

On May 4, 2021, at 10:44 AM, mesa-users at lists.mesastar.org<mailto:mesa-users at lists.mesastar.org> wrote:


On 5/4/21 4:31 AM, Amedeo Romagnolo via Mesa-users wrote:

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?

Mesa is unusually CPU-bottlenecked. Most programs tend to bottleneck on something other than CPU: For games it's generally graphics, for most programs it's user input (that is, each keystroke or click of the mouse gives them work to do, but they get it done really quickly and then head back to the break room to wait for you to give them more work and gripe to all their friends about how humans are so incredibly slow). So even if the CPU throttles due to thermal load, the processes that aren't MESA may still be able to get enough CPU time that you don't notice them lagging.

MESA, meanwhile, gives the CPU a ton of work to do, and if your computer isn't well enough ventilated for the power draw of the CPU, you may very well get thermal throttling. That's where a full-sized desktop can come in handy: you can  fit all the computing power a single person could reasonably need into a laptop these days, at least for work that comes in short bursts, but laptops are harder to ventilate and can have endurance issues because of that.

A thermal zone is basically just a temperature sensor somewhere inside your computer. What exactly each zone covers is going to vary according to your hardware, but fairly typically you might see one sensor for the whole CPU die, one for each core, one for the graphics card, and maybe one for each disk.

Jon Brase


As a fun addendum, here’s a plot of the core temperature vs time for a Raspberry Pi 4 running the MESA test suite. This is a fanless setup; the whole case, made from milled aluminum, serves as the heatsink. You can clearly see when the calculations stop!

cheers,

Rich

[cid:58EE2D40-7430-49F2-9FCB-A8C2C947791E]


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