Linux: to swap or not to swap?

[alm]

There is no shortage, so why even evict rarely used (hint: there is not such thing as unused memory that is claimed/in use by an application) if it isn't necessary?

Because for most workloads more cache is better. Some pages might only be necessary when you shut down your computer, or for remote access which you use once per month.

Keep in mind that without swap, the kernel doesn't need to keep track of which pages are used regulary and which not.

I feel like I'm repeating myself, but no this is not how it works. The kernel will still evict pages and need to keep track of which to evict, the eviction will just be limited to file backed pages. So instead of swapping out that anonymous memory allocated by a backup program that runs during the night, it might evict a font or shared library that you haven't used recently.

[magic]

(hint: there is no such thing as unused memory that is claimed/in use by an application)

In a perfect world

Keep in mind that without swap, the kernel doesn't need to keep track of which pages are used regulary and which not.

Still does. From a router with no swap support at all:

Code: [Select]

# cat /proc/meminfo
MemTotal:         126324 kB
MemFree:           96604 kB
Buffers:            2172 kB
Cached:             8808 kB
SwapCached:            0 kB
Active:             9816 kB
Inactive:           4456 kB
Active(anon):       4372 kB
Inactive(anon):       92 kB
Active(file):       5444 kB
Inactive(file):     4364 kB
blah blah

[NiHaoMike]

For well over 10 years, every PC I set up didn't have swap. Never had any problem with it.

[olkipukki]

So the question is, is a swap partition necessary for a desktop/workstation use, 64GB+ RAM and a Linux 6.x kernel?

On 64GB machine I keep a swap 'just in case' of 1/2 size of RAM.
Usually, couple VMs runs at same time, although a swap used rarely.

... and what would be any issue with not having any swap?

Trying to hibernate 256GB RAM Linux didn't end up well 

[SiliconWizard]

For well over 10 years, every PC I set up didn't have swap. Never had any problem with it.

That's also my experience, with the disclaimer - that I stated - that I haven't been running Linux for real, heavy workstation use, hence the question more aimed at this use case.
My uses have mostly been on a laptop (which has 'light' use) and a headless box that I use for development purposes. In both cases, no swap, and never had any trouble with it.

But this time, it would be for 'heavy' workstation use, and typically putting the machine in standby when not in use (no hibernation as I said), so potentially relatively long up times.

My conclusion so far is what has been said a few posts ago - I'm going to activate a swap partition on a small dedicated SATA SSD, that will also be used for cache files and otherwise content that changes frequently, so that I limit the wear on the much more expensive, NVMe SSDs that I have.