[Info-vax] report of the last "rendez-vous autour de VMS" (2-FEB-2024)

[John Dallman]

In article <uvu9t1$343t5$1 at dont-email.me>, arne at vajhoej.dk (Arne Vajhøj)
wrote:

> The problem with ARM is not that x86-64 is #1 currently.
> 
> The problem with ARM is that a lot - probably most - sites
> do not have any ARM at all.

Dead right. VMS as an OS primarily intended to be run under x86-64
virtualisation is not a problem for today's corporate datacentres.
Requiring ARM would be a significant additional barrier. 

> Requiring ARM for VMS would mean introducing a new CPU type. And 
> with todays multi-multi-core CPU's that would typical mean
> either having a lot of wasted resource by only using it for VMS
> or having to move other workloads from x86-64 to ARM to accomodate
> VMS.

Probably not, actually. The common ARM servers have Ampere Altera
many-cores processors with 64 or 80 cores. Those cores aren't very fast,
because their design prioritised low power usage. That's because their
target market was huge cloud datacentres, where their selling point is
their power efficiency reducing the cooling requirements. The square-cube
law means that in a big enough datacentre, cooling becomes the main
problem. 

Those Ampere-based servers aren't terribly expensive. If VMS can handle
80 cores, it might be quite responsive running on one. 

John