Using ZRAM or enabling ZSWAP for better performance?

[anaximeno]

I've been using ZRAM under Linux Mint for some tome and it really helps to make the system a bit faster, in Ubuntu (and ) there's a package that automatically configures ZRAM swaps on the computer called zram-config, and since I've migrated to LMDE, I was not able to use zram-config, but there's still a package that can be use to configure ZRAM under debian which is called zram-tools, but here you'll have to manually add some config files and made some modification for it to work as I wanted. I decided to make more reasearch on the topic and I've found that there's another configuration that helps improving the handling of memory in this case, called ZSWAP. This is a feature of the Linux kernel that helps the handling of swap memory, but it works in a slight different way than ZRAM, since ZRAM creates a new swap where data is compressed and added to memory (something like an in-memory swap), therefore, not needing to add another disk swap (or file swap), but ZSWAP apparently works by trying to compress some common pages that would otherwise be stored in the disk swap, and stores it in the as a cache in memory (almost like ZRAM, but with some differences) and if it was not able to compress the data to store it in the memory cache or the data requires to be stores in swap, it will be stored in the disk swap.
The reason I think ZSWAP is a good option is that the way it works integrated with disk swaps since it just works as a layer above disk swaps that stores common pages in memory (if my understanding is right), and it is best in situations where you still want to have a disk swap. ZRAM (for what I know) is generally used as the only swap type in the system (like in Fedora as an example) but they still can be used with disk swaps, and in case of using it along with disk swaps you'll have to set up right priorities for each swap type, so if you put ZRAM swaps, in the case of having disk and ZRAM swaps, with higher priority it will be used primarily above disk swaps, but if it has not more space, data will be stored in disk swaps. The problem in my view is that ZSWAPs may be more useful when you are using things like hibernation (this is enabled by default in LMDE) for example, because, for what I know (though I have to confirm this), when hibernating some of the data is store in swap, and that might be a problem if you have only ZRAM swaps (I believe) since ZRAM works in memory, maybe making hibernation an impracticable option in that case. I am only noting the problem that could happen with hibernation (on LMDE) but there might be others, and I might note them after doing more reasearch on the topic.

Refs

• https://forums.linuxmint.com/viewtopic.php?t=365232
• https://easylinuxtipsproject.blogspot.com/p/speed-mint.html#ID1.2
• https://wiki.archlinux.org/title/zswap
• https://www.kernel.org/doc/html/v4.18/vm/zswap.html
• https://www.reddit.com/r/linux/comments/vm001m/guide_setting_up_zswap/?rdt=40065
• https://www.kernel.org/doc/Documentation/vm/zswap.txt

Notes

I've been using ZRAM for more time than using ZSWAP, but until now for what I perceived ZSWAP provided an equal to (sometimes) better performance than ZRAM. But I am not completely sure on this since I just recently installed my system and using ZSAWP on my computer, and generally the systems fells faster in the first days after the installation.

If you have more info to add, or don't agree on something just say it here, and please explain why.

[anaximeno]

Just pinging @Enyc, since he seems the one to start this discussion on the Mint's community page, I would like to ear what he has to say on this.