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Is this advice also applicable to Desktops installations?
Windows and macOS have it enabled by default for many years (even if it works a little different there).
With zram, I can just use zram-generator[0] and it does everything for me and I don't even need to set anything up, other than installing the systemd generator, which on some distros, it's installed by default. Is there anything equivalent for zswap? Otherwise, I'm not surprised most people are just using zram, even if sub-optimal. [0]: https://crates.io/crates/zram-generator
Snag: I had issues getting it to use zstd at boot. Not sure if it's a bug or some peculiarity with Debian. Ended up compiling my own kernel for other reasons, and was finally able to get zstd by default, but otherwise I'd have to make/add it to a startup script.
Earlier quoted context omitted.
echo 1 > /sys/module/zswap/parameters/enabled It's in TFA.
enabling != configuring. Are you saying this is all that's necessary, assuming an existing swap device exists? That should be made clearer. Edit: To be extra clear. When I was researching this, I ended up going with zram only because: * It is the default for Fedora. * zramctl gives me live statistics of used and compressed size. * The zswap doc didn't help my confusion on how backing devices work (I guess they're any…
Is this advice also applicable to Desktops installations?
The better distros have it (ZRAM) enabled by default for desktops (I think PopOS and Fedora). In my personal experience every desktop Linux should use memory compression (except you have an absurd amount of RAM) because it helps so much, especially with everything related to browser and/or electron usage! Windows and macOS have it enabled by default for many years (even if it works a little different there).
zram size applies to uncompressed data, real usage is dynamically growing (plus static bookkeeping). Most memory compresses well, so you probably want to have zram device size even larger than physical RAM.
With zram, I can just use zram-generator[0] and it does everything for me and I don't even need to set anything up, other than installing the systemd generator, which on some distros, it's installed by default. Is there anything equivalent for zswap? Otherwise, I'm not surprised most people are just using zram, even if sub-optimal. [0]: https://crates.io/crates/zram-generator
can you make a follow-up here for the best way to setup swap to support full disk encryption+hybernation?
unfortunately you cannot chain it with any additional layer or offload to disk later on, because recompression breaks idle tracking by setting timestamp to 0 (so it's 1970 again)
https://gist.github.com/Szpadel/9a1960e52121e798a240a9b320ec...
Even "mildly" memory constrained embedded systems don't use swap because their resources are tailored for their function. And they are typically not fans [1] of compression either because the compression rate is often unpredictable.
[1] Yes, they typically don't need fans because overheating and using a motor for cooling is a double waste of energy.
Earlier quoted context omitted.
echo 1 > /sys/module/zswap/parameters/enabled It's in TFA.
enabling != configuring. Are you saying this is all that's necessary, assuming an existing swap device exists? That should be made clearer. Edit: To be extra clear. When I was researching this, I ended up going with zram only because: * It is the default for Fedora. * zramctl gives me live statistics of used and compressed size. * The zswap doc didn't help my confusion on how backing devices work (I guess they're any…
That said, if you want it to behave at its best when OOM, it does help to tweak vm.swappiness, vm.watermark_scale_factor, vm.min_free_kbytes, vm.page-cluster and a couple of other parameters.
See e.g.
https://makedebianfunagainandlearnhowtodoothercoolstufftoo.c...
https://documentation.suse.com/sles/15-SP7/html/SLES-all/cha...
I don't know of any good statistics script for zswap, I use the script below as a custom waybar module:
#!/bin/bash
stored_pages="$(cat /sys/kernel/debug/zswap/stored_pages)"
pool_total_size="$(cat /sys/kernel/debug/zswap/pool_total_size)"
compressed_size_mib="$((pool_total_size / 1024 / 1024))"
compressed_size_gib="$((pool_total_size / 1024 / 1024 / 1024))"
compressed_size_mib_remainder="$((compressed_size_mib * 10 / 1024 - compressed_size_gib * 10))"
uncompressed_size="$((stored_pages * 4096))"
uncompressed_size_mib="$((uncompressed_size / 1024 / 1024))"
uncompressed_size_gib="$((uncompressed_size / 1024 / 1024 / 1024))"
uncompressed_size_mib_remainder="$((uncompressed_size_mib * 10 / 1024 - uncompressed_size_gib * 10))"
ratio="$((100 * uncompressed_size / (pool_total_size + 1)))"
echo "$compressed_size_gib.$compressed_size_mib_remainder"