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Instant boot Linux? (lemmy.world)
submitted 2 months ago by to c/linux@programming.dev
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Hi all,

Is there a method out there that can "save a hibernate state" to disk, and just permanently boot immediately into that state every time?

It would be OK to lose data used after this point. And ot would also be OK if it required building a custom image based on the hardware, similar to embedded systems.

The goal is to be able to, as quickly as possible, spin up a GPU server when needed, but without using suspend/resume.

Thanks.

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[–] 4 points 2 months ago (7 children)

Are we talking physical servers like Poweredge or Proliant? Those take a long time to boot, especially with lots of RAM. Why can't you use suspend/resume?

And modern servers don't really consume a lot of power while idle. You can configure them to downclock the CPU and GPU while idle just like a desktop or laptop.

But if you really wanted it, you could boot an immutable distro and mount user partitions tmpfs. Or use a portable distro and discard the state. Or a filesystem with snapshots and roll back on each shutdown or boot. But none of those are really going to get you instant boot. Linux boots pretty quick, but not instant.

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  • [–] [S] 1 point 2 months ago* (4 children)

    Desktop with GPUs. I've tried immutable, but that really doesn't impact boot speed. It's still the same startup procedure. And I use ZFS, so I could roll back (or use tmpfs), but that still requires the full boot process.

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  • [–] 1 point 2 months ago (3 children)

    What's your use case or broader goal? In some specific cases you might be able to use a VM instead of a bare metal server. The host would be idling all the time, but the VM can start from a snapshot near instantly

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  • [–] [S] 1 point 2 months ago (2 children)

    Power saving with encryption at rest. I want the GPUs offline power wise.

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  • [–] 1 point 2 months ago* (last edited 2 months ago) (1 child)

    Just spitballing here, but if you use a VM with gpu passthrough, the host system doesn't even see the GPU anymore, so if the VM is off I imagine the GPU is basically off as well. In terms of encryption at rest, you can probably make a separate LUKS volume for the VM disk image, and then lock it when the VM is off.

    Edit: for example I have a VM with GPU passthrough and when the VM is off, I have no way to check the power consumption of the GPU (aside fom using external hardware) since the host doesn't have access. The host uses a sort of dummy driver for the GPU, so that the hypervisor can pass it on to the VM, so it is actually possible for the host to switch the driver and take control of the GPU when the VM is off. But until then I imagine power consumption is minimal.

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  • [–] [S] 1 point 2 months ago

    I used to do this for my virtual gaming rig, and the catch is still idle draw. Just one B70 pulls over 30W idle, then there's the nvidia card and then CPU etc, too. As this machine is solely for remote development and inference, I want it fully off.

    Now, I guess I do have all the confidential stuff in encrypted ZFS, so I can shutdown the docker containers, unmount ZFS, and suspend. This gives me encryption at rest. The problem is the startup/resume is actually slower than you might think.

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  • [–] 1 point 2 months ago* (1 child)

    Linux boots pretty quick

    I never managed to make linux boot faster than windows (on the same device ofc).

    And to this day I don't understand why.

    Out of the 3 desktop OSes (lin, win, mac) linux was always the slowest one in my experience.

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  • [–] [S] 2 points 2 months ago

    Fast boot most likely. Windows can shut down user processes and then hibernate the kernel/system processes. Because the system only changes on updates, it doesn't have to wrote the hibernate file every time, only on update. Never understood why distros didn't look to replicate that. If they had this would probably be a non-issue for me.

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