Hello Linux folks, i would like to share one little hack which i have found.
On fedora, zram-generator comes installed and configured by default with lz4 algorithm i believe, and no disk swap, if you have 8gb of ram or more, that is fine, but if you have 4gb or less, systemd-oomd either kills your games when they use too much memory, or you face an OOMD and get your system frozen.
When configuring fedora, normally i would create an in-disk swap, so that my computer wouldn’t freeze but face a MASSIVE slowdown when on way too high memory usage, i also set zram-generator to use the zstd algorithm so that zram compression rate is higher but slightly slower, like that i can use my low memory more efficiently with a lower risk of OOMD.
I was watching a bringus studios video once, where he tried to run counter-strike 2 on a ps4 using linux and proton; the game would always use too much memory and that would freeze the system before it got a change to actually launch, the strange ps4 linux was using in-disk swap, and so, increasing swapiness to 100 bringus tried to leverage that to make the game run. He was successful. In disk swap is very slow, so the performance was crap, but that does not matter…
So i had the idea to combine it with zram-swap to avoid the in-disk swap penalty, also using zstd as the algorithm to make the most out of the memory, and it was a massive sucess! Some games which would make my system very unstable or straight up freeze on certain launch attempts started launching and working just fine! and without dumb in-disk swap slowdowns!
While running modded Victoria 2 i have noticed my system using about 3.3 to 3.4GB of swap, and about 3.5 gb of ram, so about 100 to 200MB of real uncompressed memory usage, assuming zstd is running at level 1 of compression, and achieving at least 3.0 as compression rate, in thesis, my system has now the equivalent to 10GB of ram, well above it’s weight! even more impressive considering how low are the numbers we are working here!
tldr: setting your swapiness=100 while using zstd as your zram-generator compression algorithm, and no in-disk swap will help your system use the most out of your ram with negligible performance penalty
archwiki tuning has a listing with swappiness set up to 180 (yes apparently the number can go over 100)
Number is priority level, 100 is equal priority as real ram, over 100 is higher priority than real ram, less than 100 is less priority than real ram, and as far as I’m aware, max number is 200 and minimal number is 0
Now I’m curious: Could something similar also be done for VRAM?
i dont think so
I tried to look to see if vram could have something like zram on it but from what I found it’s either not possible or not logical to do so because it’s different from regular ram
Now this is gaming
very gaming indeed
Yeah, with zram I was able to actually play Cities Skylines on my Steam Deck.
The Steam Deck has shared RAM for the CPU and GPU, right?
Yeah. I didn’t dare giving 100 % RAM to zram.
Not infinite ram. I’d say double ram, plus there is a noticable, but quick delay when switching to an application that was compressed by ram. But it’s much, much faster than switching to an app that was swapped to disk.
Cachyos (arch based distro) does this hy default.
CachyOS mentioned! CachyOS btw
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don’t be silly, of course it’s not infinite ram, the only way to get infinite ram is if you download it.
Do you need a swappiness over 1 if you don’t have another swap device?
swapiness =/= priority, if your swapiness is at 1, the kernel is never going to use the device, if the number is high(like 100) every opportunity the kernel sees to put stuff in the swap, it is going to.
Will it not use it even after the ram fills up? I wouldn’t want the compressed part be prioritised anyways
it won’t let your ram fill up, i’m quite sure that when you get a high enough memory usage the kernel just starts dumping stuff into swap anyway
Wouldn’t it be easier to just put 8gb of ram in the system?
In my country that would cost me 20 dollars, what an absurd!
You could get a used stick from an junk dealer. Maybe I’m missing something but $20 doesn’t seem like a lot. It is higher than I’d expect but not unreasonable
Every dollar/cent counts for some of us.
In my country that would cost me 20 dollars
The first RAM I bought (SIPP for a 386-16 IIRC) was $50/MB. Jay-sus.
When do you think will Valve enable this by default in SteamOS? It would greatly help the little Steam Deck with playing more performance-intensive titles.
The improvement you are describing is the default out of the box experience on pop os
Any other distro really…except Ubuntu
Or Arch if you don’t explicitly set it up yourself lol
Oh. Right. Yea that one too lol
Or Gentoo, Void, Alpine, I could go on and on
But these distros hardly set up anything for you out of the box, they’re meant to be configured manually
But I can see Arch including an option for this in their install script at some point in the near future
Am I the only one that pronounces it swa-penis and giggles every single time?
Yeah
Peter griffin what you are you doing here?
[…] with negligible performance penalty
Which CPU do you have?
11th Gen Intel Core i3-1115G4 @ 4x 4.1GHzaccording to screenfetch, in practice i get at most 3.9ghz on cold days, and 3.4 on the other ones; the cpu is running at 70°C on idle right now.send help, global warming and the local corporations are turning my nice little city into an unbearable helledit: screenfetch doesn’t seem to be accurate with temps, i’m getting 46°C at idle
Am I right to assume you’ve got a laptop? Otherwise 70C is a terrible temp to hit at idle
yep
Considering how much faster my CPU is than my ram, even though they are both 12 years old, I should do this 😹
Great post!
Is it because Fedora doesn’t enable zswap by default?
https://wiki.archlinux.org/title/Improving_performance#zram_or_zswap
https://wiki.archlinux.org/title/Zswap
https://wiki.archlinux.org/title/Zram
One down side of zram is that you won’t be able to hibernate to swap, if that’s a requirement. On consoles this might be totally irrelevant though.
they do, but it uses the lz4 algorithm by default, which doesn’t offer the highest compression rate, also the swapiness is not 100 by default.
