5 ms·

I've been using unikraft (https://unikraft.org/ https://unikraft.org/) unikernels for a while and the startup times are quite impressive (easily sub-second for

by droelf 9mo ago

I've been using unikraft (https://unikraft.org/ https://unikraft.org/) unikernels for a while and the startup times are quite impressive (easily sub-second for our Rust application).

ahepp 9mo ago
What drove you to choose that over something like containers?
- m00dy 9mo ago
  shorter cold-boot times.
  - ahepp 9mo ago
    If we’re talking about cold boot times, wouldn’t the relevant metric for unikernels be the hypervisor’s boot time?
  - zozbot234 9mo ago
    How would that compare with containers running on Firecracker or other virtio-based μVM's?
    - wmf 9mo ago
      A unikernel on Firecracker is probably going to start faster than a container on Linux on Firecracker.
      - ahepp 9mo ago
        I assume they meant using an OCI image for the rootfs of a firecracker VM, not running a container inside a firecracker VM. Still difficult to see how the unikernel could be slower, but I doubt the difference would be huge? Don't have anything to back that up though.
- droelf 9mo ago
  Yeah, boot time, isolation (proper VM vs containers), and ease of use on a larger Hetzner box.
  - ahepp 9mo ago
    Did you notice a substantial difference in those factors between more traditional micro VMs that use OCI images (like Firecracker) and unikernels?
ATechGuy 9mo ago
Fast boot up means nothing if your agent/app is slow at runtime (due to virtualization tax or QEMU emulation). Fast boot up is a PR term, which can easily be optimized for compared to designed a better virtualization layer that performs near-bare-metal.
- wewtyflakes 9mo ago
  Wouldn't faster boot times mean that scale-out can be done on-demand? Whether this is preferable or not over poorer runtime performance is up to the domain, no?
  - ATechGuy 9mo ago
    When scaling out, edge latency will overshadow kernel boot-up times: speeding up boot-up from 1.5s to 150ms will not have any perceived impact on app performance when scaling on edge to meet the demand.

by droelf 9mo ago

I've been using unikraft (https://unikraft.org/ https://unikraft.org/) unikernels for a while and the startup times are quite impressive (easily sub-second for our Rust application).

ahepp 9mo ago

What drove you to choose that over something like containers?

m00dy 9mo ago
shorter cold-boot times.
- ahepp 9mo ago
  If we’re talking about cold boot times, wouldn’t the relevant metric for unikernels be the hypervisor’s boot time?
- zozbot234 9mo ago
  How would that compare with containers running on Firecracker or other virtio-based μVM's?
  - wmf 9mo ago
    A unikernel on Firecracker is probably going to start faster than a container on Linux on Firecracker.
    - ahepp 9mo ago
      I assume they meant using an OCI image for the rootfs of a firecracker VM, not running a container inside a firecracker VM. Still difficult to see how the unikernel could be slower, but I doubt the difference would be huge? Don't have anything to back that up though.
droelf 9mo ago
Yeah, boot time, isolation (proper VM vs containers), and ease of use on a larger Hetzner box.
- ahepp 9mo ago
  Did you notice a substantial difference in those factors between more traditional micro VMs that use OCI images (like Firecracker) and unikernels?

ATechGuy 9mo ago

Fast boot up means nothing if your agent/app is slow at runtime (due to virtualization tax or QEMU emulation). Fast boot up is a PR term, which can easily be optimized for compared to designed a better virtualization layer that performs near-bare-metal.

wewtyflakes 9mo ago
Wouldn't faster boot times mean that scale-out can be done on-demand? Whether this is preferable or not over poorer runtime performance is up to the domain, no?
- ATechGuy 9mo ago
  When scaling out, edge latency will overshadow kernel boot-up times: speeding up boot-up from 1.5s to 150ms will not have any perceived impact on app performance when scaling on edge to meet the demand.