[Info-vax] Kernel Transplantation (was: Re: New CEO of VMS Software)

[Lawrence D'Oliveiro]

On Sat, 6 Jan 2024 20:31:22 -0000 (UTC), Dan Cross wrote:

> But that's not what he actually said: you omitted the critical word,
> "kernel", as in _kernel resources_ used by different users.

Since *all* resources are defined (and managed) as such by the kernel, I 
fail to see what the distinction is.

cgroups let you manage CPU time usage and CPU affinity (are CPUs a 
“kernel” resource?), memory usage (is that a “kernel” resource?), I/O 
usage (is that a “kernel” resource?), RDMA usage (is that a “kernel” 
resource?), numbers of processes created (is that a “kernel” resource?) 
etc etc.

Otherwise, feel free to explain what the distinction is between a “user” 
resource and a “kernel” resource.

>>Remember that my proposal for adopting the Linux kernel would get rid of
>>every part of VMS that currently runs at higher than user mode. It's
>>only their own user-mode code that customers would care about.
> 
> You think that's easy, but it is clear that you really don't understand
> the issues involved.

The poster I was replying to already conceded this point.

> Containers started as a way to run multiple versions of some very large
> programs with disparate library and other dependencies on a single
> system, and grew into a mechanism for managing resources generally.

You are thinking of Docker. Which is just one kind of “container” 
technology. Remember that “containers” as such do not exist as a built-in 
primitive in the Linux kernel: they are constructed out of a bunch of 
lower-level primitives, including cgroups and the various kinds of 
namespaces. This allows for very different kinds of technologies to be 
built that call themselves “containers”. And for them to coexist.

> Every Mac on the planet runs more or less a version of Mach+BSD.

And doesn’t exactly do so well. Back when Apple sold servers, I remember a 
review of MySQL running on OS X Server versus Linux, on the same hardware. 
Linux ran circles around Apple’s microkernel-based OS. On the company’s 
own hardware.

> The Intel ME embedded in most Intel CPUs runs Minix3.

Bad, bad example.
<https://arstechnica.com/information-technology/2017/05/the-hijacking-
flaw-that-lurked-in-intel-chips-is-worse-than-anyone-thought/>