CentOS 7 host with 22.04 LTS guest slow

[Ralf Mardorf]

On Mon, 2022-09-26 at 21:14 +0100, Colin Law wrote:
> On Mon, 26 Sep 2022, 21:06 Jerry Geis, <jerry.geis at gmail.com> wrote:
> 
> >  I am surprised that my "appearance" of disk speed like compile time
> > is not faster.
> 
> If using a faster disc has not speeded it up then that suggests that
> disc access is not the dominant factor. When you are building, what
> does `top` show? Perhaps it is processor speed that is the limiting
> factor.

My machine has got a quite weak Intel Celeron dual-core CPU G1840,
2.80GHz. There's no noticeable difference between building something by
using a default 7.6G (half of the RAM) tmpfs or a SATA 6GBit/s SSD ext4
partition. IIRC there is _no_ significant difference when using a HDD,
too. With half of the RAM I was already able to use tmpfs for almost
everything, e.g. even a bloated kernel, but not a bloated web browser.
The issue with tmpfs is, that it not only can run out of free space. It
can also run out of inodes, while enough free space is still available.
However, in almost all cases it doesn't make sense to use a HDD, SATA
SSD or NVMe, even with a small memory. With your 128G RAM large memory,
consider trying to build everything using tmpfs instead of a disk. For
what else do you have got such an oversized large RAM, if not for
intensive tmpfs usage?