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

[Phillip Susi <phill@xxxxxxxxxxxx>]

Michael Chapman <mike@xxxxxxxxxxxxxxxxx> writes:

> 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;

That's the wrong question.  The question is, what is the difference
between having NO swap, and having some swap that you don't use much of?
The answer to that is that there will be a non zero amount of anonymous
memory allocated to processes that hardly ever touch it, and that can be
tossed out to swap to provide more memory to use for, if nothing else,
caching files that ARE being accessed.  Now that amount may not be much
if you usually have plenty of free ram, but it won't be zero.

I too have long gone without a swap partition because the small benefit
of having a little more ram to cache files did not justify the risk of
going into thrashing mode when some process went haywire, but if that
problem has been solved, and you want a swap partition for hibernation
anyhow, then you may as well keep it mounted all the time since
unmounting it when you aren't about to hibernate costs *something* and
gains *nothing*.