I got a cheap netbook style laptop for traveling some weeks ago (HP Stream 11" with 4 GB of RAM and a N4120). Didn’t expect much more from this hardware than opening a few browser tabs and doing some retro gaming via Steam.
Shared RAM with graphics card means that 3.64 GB of RAM are effectively usable for the OS. This was even too little RAM to open a handful of tabs w/o having tabs being unresponsive for seconds sometimes in a very annoying way. Another thing which made trouble was the Wifi - I guess it went into power saving, was swapped and didn’t load fast enough to provide a good experience. (Of course I wasted an hour checking for Wifi drivers/support.)
In short: Even for my low expectations for this laptop it was an underwhelming experience.
First step was to look at my vm.swappiness and set it to 10, which already helped, but still the machine had hiccups and annoying timeouts.
In a last, desperate effort I enabled ZRAM on the laptop… and literally WTF: Saying it is a night and day difference doesn’t do the experience justice. Typing this words now on the Stream, which I use exactly the same way as my much more beefy other machines (my next worst computer has 8G of RAM and an Intel Core i3), browsing with 10 open tabs, e-mail client open on another virtual desktop… it is crazy, it makes the Stream fun to use and I use it at home for everything which isn’t heavily CPU/IO bound.
What surprised me the most: No hiccups, no timeouts and it even fixed the Wifi issues on this little machine. Didn’t expect this would be possible, especially with a N4120 and 3.64 GB of RAM.
In short, my laptop changed from not even reaching my low/realistic expectations to being my favorite technical purchase of the last years, thanks to ZRAM.
Besides making this a ZRAM appreciation post, I really want to spread the word about it. Especially for old hardware and limited RAM situations, IMHO it should be the first thing which comes to mind/is recommended.
Fedora and PopOS use it by default, so it is well tested and should IMHO again, be a default at least for desktop setups.
Give it a try - supposedly it even improved the experience on much more beefy computers for gaming etc.
I’m not going to remember the right terminology, but you can also configure it with a chunk of disk to stick files that it can’t compress into so they don’t end up clogging up your swapspace.
Not sure if you are referring to ZSWAP, which is backed by physical swap and writes uncompressable pages to the physical swap. ZRAM has AFAIK an option called WRITEBACK, which allows it to also use physical swap, but I didn’t find that ZRAM is concerned if it can compress the page or not. (Grain of salt and if someone is more knowledgeable I happily be corrected.)
I’m talking about ZRAM and I did mean writeback.
“With CONFIG_ZRAM_WRITEBACK, zram can write idle/incompressible page to backing storage rather than keeping it in memory.”
From https://www.kernel.org/doc/html/latest/admin-guide/blockdev/zram.html
Thank you.
One naive question, because it honestly confuses me:
Right now, my ZRAM swap space has a higher priority than my physical swap space. In my tests, this does what I would expect: It doesn’t touch physical swap before the ZRAM is filled.
In my mind, it works like this: I should be better off, with this setup as long as my swapping always only touches the ZRAM.
If I configure writeback, does it mean that ZRAM could just write pages out before it is filled, because the algorithms decide the page is IDLE/does not compress. Additional it seems it could wear out my flash memory (“If there are lots of write IO with flash device, potentially, it has flash wearout problem so that admin needs to design write limitation to guarantee storage health for entire product life.”).
In short, for me it looks like a worse option in my use case compared to the two separate swap partitions. Any thoughts?
