Hi,

Do you have suggestions for kernel tweaks for getting the most out of a RAM limited system?

I am running a service requiring 2GB of RAM (netbird) on a VPS which has just 1 GB of memory. I am doing so because I am a stingy bastard and I use only free VPSs for my personal use so I get what I am paying for.

Because of this hardware limit in about 12 hours from service start I begin swapping a bit too much. This would still be manageable but soon the hypervisor gets really pissed and steals up to 90% of the CPU. So the only solution so far is restarting the docker containers every 12 hours (not great, not terrible).

Looking to improve this, Iam now experimenting with ZRAM and swappiness and it seems some benefit can be achieved by using some of the Linux kernel feaures. Is there anything else I should look into?

  • henrikx@lemmy.dbzer0.com
    link
    fedilink
    arrow-up
    3
    ·
    1 year ago

    It seems to me you are already looking into all the possible options besides getting a VPS with more RAM. I am a bit confused on why you are seeing increased CPU usage by the hypervisor for this though.

    • aesir@lemmy.worldOP
      link
      fedilink
      arrow-up
      4
      ·
      1 year ago

      The server is clearly overloaded, as soon as I start using some 10% of CPU frequently for some minutes (due to swap operations), the Hypervisor starts to throttle my instance and this of course makes the thing worse with an avalanche effect. When this happens steal time displayed from top can go literally as high as 90%.

      • bruce965@lemmy.ml
        link
        fedilink
        arrow-up
        5
        ·
        edit-2
        1 year ago

        On AWS they have something called “bursting”. Basically they will let you use 100% of your vCPU, but not all the time. If you use it constantly they start to throttle you. That’s explicitly stated when you rent an EC2 instance (which is their VPS). Perhaps your provider is doing something similar.

        • aesir@lemmy.worldOP
          link
          fedilink
          arrow-up
          2
          ·
          1 year ago

          Yes exactly, burstable instances it’s common jargon for AWS and GCP, but applies to all major providers.

        • falsem@kbin.social
          link
          fedilink
          arrow-up
          1
          ·
          1 year ago

          Yeah, those are great for something that will be sitting idle most of the time, awful for anything else.

      • Lojcs@lemm.ee
        link
        fedilink
        arrow-up
        2
        ·
        1 year ago

        Ask the provider not to throttle you then? Are you not entitled to the entire cpu?

        • aesir@lemmy.worldOP
          link
          fedilink
          arrow-up
          2
          ·
          1 year ago

          I believe it’s a shared VCPU intentionally, I will recheck the terms and conditions, but I think I am not in the position to claim much.