More Memory leads to More CPU?

blindguynar

Cadet
Joined
Feb 20, 2023
Messages
7
I run TrueNAS Scale via a Proxmox Container and i have been starving it a bit on memory. I'd only given it 16GB of Ram and 4 Cores. Since i recently starting doing some Jellyfin streaming off the Share i decided to give it more memory so it would cache the movie i was playing for better performance. i gave it 32GB as the movies are typically 20GB or so. I have much more memory i could give actually, but i try to live by the hyperviser thought of giving it just what it requires.

However, on to the issue. The CPU when NUTS after i did it. Pulsing up to 90%, back down, 50%, 90%, back down, etc, etc. I didn't actually even get around to testing a movie as i got wrapped up in something else. I noticed it the next day. I first tried just a reboot to see if it would settle down and it had nearly same behavior. So i cut the memory back down to ~16GB and it settled down right away back to normal.

I searched and couldn't find anything to suggested any sort of CPU core increase was needed for a Memory increase. In fact everything simply says the MORE memory the better for performance. Recommended CPU is 4 cores which is what it has. Does more memory need more cores? I think not right? The CPU seemed to grow of the 24hr or so period, so i thought first rouge process, but then it didn't settle down at all from a reboot and i even shutdown all other containers that access any shares on the truenas container.

I'm fairly certain > memory doesn't require > cpu, but maybe i've just not read the right article.

Before and After Metrics on the Container below.

Any idea's from the collective here? Looking for idea's before i just try it again. I've have thought 24hrs would have been ample time for it to have settled into the new memory.

HyperViser: Proxmox 8.0.4
Running BlueFin: TrueNAS-SCALE-22.12.4.2
VM: 4 Cores, Memory 16GB-32GB
CPU @ 16GB < 5%
CPU @ 32GB = CRAZY NUTS and it directly correlates to the memory increase.
 

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Davvo

MVP
Joined
Jul 12, 2022
Messages
3,222
You cannot use common sense on a virtualized istance. I do not virtualize, but I can tell you it's not TN standard behaviour (bare-metal or virtualized).
Also, SCALE can only use half of the RAM you give it for caching.
 

blindguynar

Cadet
Joined
Feb 20, 2023
Messages
7
I bumped memory to 48gb and i'm no longer witnessing the previous behavior over the previous 24hrs.
 
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