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Comment on Help with understanding memory usage discrepancy

This is why I’d like to know what tool shows the most useful number. If I only have 4GB out of 30GB left, is that 26GB difference mostly important processes or mostly closable cache? Like, is htop borked and not showing me useful info or is it saying 8GB of the 26GB used is important showstopping stuff?

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rtxn@lemmy.world ⁨1⁩ ⁨day⁩ ago
The most useful is probably cat /proc/meminfo. The first couple of lines tell you everything you need to know.

MemTotal is the total useful memory.

MemFree is how much memory is not used by anything.

Cached is memory used by various caches, e.g. ZFS. This memory can be reallocated.

MemAvailable is how much memory can be allocated, i.e. MemFree + Cached.
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- a_fancy_kiwi@lemmy.world ⁨1⁩ ⁨day⁩ ago
  You’re an angel. I don’t know what the fuck htop is doing showing 8GB in use. For anyone else who comes across this, this is what I have. This makes the situation seem a little more grim. I have ~2GB free, ~28GB in use, and only ~3GB is cache that can be closed. For reference, I’m using ZFS and roughly 27 docker containers. It doesn’t seem like there is much room for future services to selfhost.
  
  MemTotal: 30.5838 GB MemFree: 1.85291 GB MemAvailable: 4.63831 GB Buffers: 0.00760269 GB Cached: 3.05407 GB
  
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  - rtxn@lemmy.world ⁨1⁩ ⁨day⁩ ago
    You should also look at which processes use the largest amount of memory. ZFS is weird and might allocate its cache memory as “used” instead of “cached”. See here to set its limits: forum.proxmox.com/…/limit-zfs-memory.140803/
    
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    a_fancy_kiwi@lemmy.world ⁨1⁩ ⁨day⁩ ago
    Assuming the info in this link is correct, ZFS is using ~20GB for ARC which makes htop’s 8GB of in use memory make sense.
    
    My results after running cat /proc/spl/kstat/zfs/arcstats:
    
    c 4 19268150979 c_min 4 1026222848 c_max 4 31765389312 size 4 19251112856
    
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  - Voroxpete@sh.itjust.works ⁨1⁩ ⁨day⁩ ago
    Most of those containers are probably grabbing more memory than they actually need. Consider applying some resource constraints to some of them.
    
    Dozzle is an excellent addition to your docker setup, giving you live performance graphs for all your containers. It can help a lot with fine tuning your setup.
    
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    irmadlad@lemmy.world ⁨23⁩ ⁨hours⁩ ago
    
    Most of those containers are probably grabbing more memory than they actually need.
    
    It took a bit of trial and error with Portainer, but under Runtime & Resources, you can adjust the amount of needed resources:
    
    Shared memory size
    
    Memory reservation (MB)
    
    Memory limit (MB)
    
    Maximum CPU usage
    
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