You only want to use zram if you've got no swap device (e.g. a raspberry pi).
If you do, you'll want zswap instead.
I've heard ZRAM mentioned before and I've just spent 5 minutes reading articles on it... Which is about the maximum I have time for these days when it comes to esoteric linux internals.
What's the downside? Does it use much CPU?
If I have enough RAM already, should I still enable it?
One article says it can be mapped to /tmp to reduce i/o. Is that a good idea?
This article is light on all of these kind of details.
I remember that back in around 2007 i was able to somehow mount a graphical card (ati similar to geforce2?) memory directly in Linux, and put my swap file there :); Great times. Slackware 8.1 i think.
as for zram: somehow i dislike it. Nowdays ram is plenty and if not: better to have fast OOM than chug of death with swap.
I also remember running NetBSD 1.3.1 and Slackware 3 on 386SZ 26MHZ with 2 mb of ram (nowadays hard limit is 4mb to boot due the large memory pages on x86 afik)
There's also kernel zswap, right?
https://www.kernel.org/doc/html/latest/admin-guide/mm/zswap....
Oh right, definitely. Chrisdown wrote an article comparing the two:
https://chrisdown.name/2026/03/24/zswap-vs-zram-when-to-use-...
Zswap is supposed to degrade more gracefully.
There's even some HN comments on it:
https://news.ycombinator.com/item?id=47500746