about swap

[Manessa]

I have a slightly strange question. I noticed that I have 8 GB of RAM, and when I consume 4 GB of RAM (I launched a torrent), and the RAM is not completely full, then for some reason the system goes into swap, although the memory is still remained. Why is this happening?

[stevef]

There's an article at this link, mainly about swappiness but it includes a brief overview of the swap trigger thresholds.

https://www.howtogeek.com/449691/what-is...lly-cut-in

[trinidad]

Nowadays swap is is quite relative to what a user is asking the system to do. Tweaking it one way or the other depends on the frequency of heavy loads on the system, i/e you may be back-grounding data analysis while browsing or running an office application. Torrent could also depend on the speed capability of your network card and its distribution across the internal port limitations which may access out slower recall pages to avoid bottlenecks. In Debian this has been a source of argument ever since onboard RAM began to exceed 4G. Years ago swap always used a partition which was equal to the available RAM. This is no longer the case and default Debian installs a 1G swap file or partition. Performance tweaking depends specifically on user needs. Many things can cause the use of swap regardless of available memory and usually the reasons for swap usage are advantageous and sensible. Finally it's difficult in some cases to change an application's memory mapping once it has mapped to swap, meaning reducing swappiness to lower numbers (go from 60 to 0) may not change a specific application's mapping and performance will get worse rather than better. In certain cases (heavy VM usage) vfs_cache pressure settings can affect performance as well. I guess the upshot here is that though your system seems to swapping out for no reason (though memory utilities that measure available RAM are generally inaccurate) it is probably advantageous that it is. If this was a specific single use occurrence I would stay with the default settings.
TC