Re: how to let systemd hibernate start/stop the swap area?

[Michael Chapman <mike@xxxxxxxxxxxxxxxxx>]

On Fri, 31 Mar 2023, Lennart Poettering wrote:
> On Fr, 31.03.23 07:57, Michael Chapman (mike@xxxxxxxxxxxxxxxxx) wrote:
> 
> > On Fri, 31 Mar 2023, Luca Boccassi wrote:
> > [...]
> > > No, it does not make "little difference", there are entire subsystems
> > > which are much worse off, if not completely useless, without swap.
> > > Post-cgroupsv2 memory controller things are considerably different on
> > > this front, and old "common wisdom" no longer applies.
> >
> > What are some examples here?
> >
> > What specifically is the difference between:
> >
> > * swap does not exist at all;
> > * swap is full of data that will not be swapped in for weeks or
> >   months;
> 
> The big difference is that the RAM that became available because the
> unused stuff was swapped out has been applied to better uses,
> i.e. keep more frequently used stuff around, improving performance of
> the often used stuff, at the price of degrading peformance of the
> apparently never used stuff. Overall win!

Honestly, I feel that I've covered this already... but I'll try again.

It is only a win if that actually results in better performance! If all 
you've done is swapped out a whole lot of data, but the rest of the system 
still has the same performance, you're _worse_ off.