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Re: Status of NetBSD virtualization roadmap - support jails like features?

At Fri, 15 Apr 2022 07:36:15 +0200, Matthias Petermann <> wrote:
Subject: Status of NetBSD virtualization roadmap - support jails like features?
> My motivation: I am looking for a particularly high performance
> virtualization solution on NetBSD. Especially disk and network IO
> plays a role for me.

In my experience nothing beats I/O performance of Xen with LVM in the
dom0 and the best/fastest storage available for the dom0, especially now
there's SMP support for dom0.  That's anecdotal though -- I haven't done
any real comparisons.  I just know that NFS in domUs is a lot slower
than using LVMs via xbd(4), no matter where/how-fast the NFS server is!

If I'm not too far out of touch I think there's still a wee bit more SMP
support needed in the networking code to make it possible for dom0 to
also give the best network throughput, but it's really not horrible as-is.

In theory NVMM with QEMU and virtio(4) should be about the same I would
guess, with potential for some improvement in some micro-benchmarks, but
for production use the maturity and completeness of the provisioning
support offered by Xen still seems far superior to me.

> Regardless, I still think it wouldn't hurt
> if NetBSD could implement some sort of
> jail.

I'm not convinced "jails" (at least in the FreeBSD form I'm most
familiar with) actually buy much without also increasing complexity
and/or introducing limitations on both the provisioning and the
"virtual" side.

With a full virtualisation as in Xen the added complexity is very well
partitioned between the provisioning side and the VMs, and there are
almost no limitations inside the VMs (assuming you are virtualising
something that fits well into a virtualised environment, i.e. with no
special direct hardware access needs) -- everything looks and feels and
is managed almost as if it is running on bare hardware and so the
management of the VM is exactly as if it were running on separate
hardware; except of course some aspects are actually easier to manage,
such as provisioning direct console access and control.  There's really
nothing new to learn other than how to spin up a new domU (and possibly
how to use LVM effectively).

However FreeBSD-style jails do offer their own form of flexibility that
seems to be worth having available, and it would be nice for jails to be
available on NetBSD as well.  The impact inside the OS (kernel and
userland) is quite high though, and is itself a form of complexity
nightmare all its own, though perhaps not so horrible as Linux "cgroups"
and some other related Linux kernel namespaces are.

					Greg A. Woods <>

Kelowna, BC     +1 250 762-7675           RoboHack <>
Planix, Inc. <>     Avoncote Farms <>

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