I have 20GB in my current setup and it was never full. If anything gets swapped in this situation it means it needlessly slows me down.
Not necessarily. Your memory also contains file backed pages (i.e. “file system cache”). These pages are typically not counted when determining “memory usage”, because they can always be discarded.
It is often advantageous to keep frequently use files in cache in favor of unfrequently used memory pages.
I’ve never understood why GNU/Linux actually needs swap
It doesn’t. It’s just good to have in most circumstances.
Also, sidenote: “GNU” doesn’t apply here. Swapping is purely kernel business, no GNU involvement here.
Okay, I created a 4G partition for it, having 32G of RAM. I never used all that RAM, but even so, stuff regularly ends up in swap. Why does the OS waste write cycles on my SSD if it doesn’t have to?
Physical memory does not just contain program data, it also contains the filesystem cache, which is also important for performance and responsiveness. The idea is that some of the least recently used memory pages are sometimes evicted to swap in favor of more file caching.
You can tweak this behavior by setting the vm.swappiness kernel parameter with sysctl. Basically higher values mean higher preference for keeping file backed pages in memory, lower values mean higher preference for keeping regular memory pages in memory.
By default vm.swappiness = 60. If you have an abundance of memory, like a desktop system with 32G, it can be advantageous to lower the value of this parameter. If you set it to something low like 10 or 1, you will rarely see any of this paradoxical swap usage, but the system will still swap if absolutely necessary. I remember reading somewhere that it’s not a good idea to set it to 0, but I don’t remember the reason for that.
Alternatively, there is no rule that says you can’t disable swap entirely. I’ve run a 32G desktop system without any swap for years. The downside is that if your 32G does run out, there will be no warning signs and the OOM killer will unceremoniously kill whatever is using the most memory.
tl;dr just do this:
sysctl vm.swappiness=10
echo "vm.swappiness=10" > /etc/sysctl.d/99-swappiness.conf
I run a lot of VMs; I typically run 2 at the same time in addition to running other programs in the background, my usecase is more eccentric than most users in the Linux space which is already pretty niche
If what you’re doing involves using close to all of your system memory, it does make sense to add swap. So your use case is a good example actually.
I also have an old Arch PC that I use to run various VMs on (currently 6 VMs in use). It does have a swapfile, but the most swap I’ve ever seen in use is about 1GB.
I’m using BTRFS with LUKS-based Full Disk Encryption, the last time I used swapfiles with BTRFS with FDE it was in 2019 and it was painful to say the least, I rememeber spending several weeks scouring Stack and the Arch forums in order to get it to work properly.
Weird. Sounds like you may have painted yourself a bit into a corner by using BTRFS then. I use trusty old ext4 on top of LUKS FDE, no issues with swapfiles whatsoever.
That brings me to another downside of swap partitions: encryption. You can leak sensitive data through your swap partition, so it should be encrypted. If you use a plain partition, without LUKS in between, information in your swap is exposed. So you need to do more configuration to setup LUKS on your swap partition.
If you use a swapfile on an already encrypted filesystem though, you don’t have to worry about it.
when would I even want to resize swap for a single system
Maybe your requirements change (e.g. “I want to be able to hibernate”), maybe your memory configuration changes, maybe you’ve underestimated or overestimated how much swap you need.
Case in point: the Arch PC I mentioned above only uses upto 1GB of swap, but it has a 16GB swapfile. This discussion has brought to my attention that perhaps I should downsize the swapfile a bit and free up disk space.
you don’t really want to depend on swap if can
That is my position too. It’s always better to have a properly sized system, or limit what you push on an existing system. High swap usage rarely results in a good experience.
0 swap: which was pretty awful with constant unexpected system freezes/crashes
I’ve run Arch without swap for many years without issues. The key of course is that you need enough RAM for what you are trying to do with your computer.
There’s no reason why a 32GB RAM + 0GB swap system should have more problems than a 16GB RAM + 16GB swap system with the same workload. If anything, the former is going to run much better.
swap file: finicky but doable
What is finicky about a swap file?
It’s just this:
mkswap -U clear --size 4G --file /swapfile
swapon /swapfile
Done
If anything it’s way easier to create a file in your filesystem than having to (re-)partition your drive to have a swap partition. Much more flexible too if you want to change your swap configuration in the future.
X thing you want isn’t the devs job
Well, it is if they decide it is, and it isn’t if they decide it isn’t.
That said, I do appreciate devs who put up native deb or rpm repos for the most common distros.
It isn’t your computer, user license clearly states you’re renting the software
It IS your computer, it’s just not your software.
Actually lot less than the browser. Under 300MB, I just checked, and that’s mostly just the network buffer which is 150MB by default.
The point is that your example use case of “YouTube 4k videos” doesn’t need a browser full of bloated js garbage.
Just don’t compain that YouTube doesn’t play 4K videos anymore.
strange, mpv handles it just fine
I remember when I got my first computer with 1GB of RAM, where my previous computer had 64MB, later upgraded to 192MB. And there were only like 3 or 4 years in between them.
It was like: holy shit, now I can put all the things in RAM. I will never run out.
Yeah and Flatpaks also exist.
Flatpaks are probably the best generic solution for using an LTS release like Debian Stable on a desktop system. You get the best of both worlds: up to date desktop packages and a stable base.
who is going to use a VPN (an internet privacy tool) from Google?
Exactly. That would be like using a web browser made by Google so they have direct access to your internet browsing history. Ridiculous!
Slashdot still exists, but it was mostly popular in the late 90s to mid 2000s.
I mean, he was still reading Slashdot, so I guess “yes”
Hmm, I can’t say that I’ve ever noticed this. I have a 3950x 16-core CPU and I often do video re-encoding with ffmpeg on all cores, and occasionally compile software on all cores too. I don’t notice it in the GUI’s responsiveness at all.
Are you absolutely sure it’s not I/O related? A compile is usually doing a lot of random IO as well. What kind of drive are you running this on? Is it the same drive as your home directory is on?
Way back when I still had a much weaker 4-core CPU I had issues with window and mouse lagging when running certain heavy jobs as well, and it turned out that using ionice helped me a lot more than using nice.
I also remember that fairly recently there was a KDE/plasma stutter bug due to it reading from ~/.cache constantly. Brodie Robertson talked about it: https://www.youtube.com/watch?v=sCoioLCT5_o
I run a pihole as well, but it is a very rudimentary tool compared to browser based adblockers like uBlock origin. It can only block DNS queries, and can’t for example block ads if they are served from the same domain as the main site (i.e. youtube) or block specific elements on a page or block a specific script from running.
only this time they’ve got a decade of research behind them and maybe they get the bomb first
Maybe that’s why we’re living in the universe where this didn’t happen, because in the universe where it did, we wouldn’t exist (many worlds/anthropic principle interpretation)
Ah, so you’re wanting to transport tons and tons of batteries back to a centralized facility to be inspected and have testing done?
No, that’s just something new you invented to shoot down the idea.
Batteries can have a tamperproof seal so that customers can’t easily mess with it, just like you normally don’t mess with the electricity, gas or water meter in your home. QC and charging can be done on site where you swap, and can mostly be automated. The only thing that needs to be transported back and forth regularly are defective and replacement batteries. Just like gas stations at the end of the day or week need to order replenishment for the fuel they’ve dispensed.
We already do this kind of swapping with other stuff as well: from crates with empty beer bottles and office water cooler bottles to refilling propane and butane bottles.
It’s not a gov problem, it’s a logistics issue.
The lack of government oversight that you brought up, and which this was in reply to, is literally a government issue. Regulation and inspection works fine in most of the civilized world, the fact that it doesn’t in Backwater USA is no argument.
Fossil fuel distribution already is a huge logistics issue, we have to dig it up in the middle east, transport it in oil tankers, refine it at some central locations, then distribute it again with tanker trucks to millions of gas stations so that finally you can put it in your car and use it to drive somewhere, but somehow we have been making that work for over a century.
Quality control on batteries that go out to customers, and make the stations legally liable.
For example: I once pumped petrol in my diesel car due to human error by the gas station’s supply company (they put petrol in the diesel tanks). They found out about the error as I was filling up and stopped me halfway, so luckily I had no engine damage, but they had to pay for the tow and to get my tank emptied.
how many states with counties have no inspections
Sounds more like a “your government is shit” problem than a “this scheme can’t work” problem.
Actually… as a former DBA on large databases, you typically want to minimize swapping on a dedicated database system. Most database engines do a much better job at keeping useful data in memory than the Linux kernel’s file caching, which is agnostic about what your files contain. There are some exceptions, like elasticsearch which almost entirely relies on the Linux filesystem cache for buffering I/O.
Anyway, database engines have query optimizers to determine the optimal path to resolve a query, but they rely on it that the buffers that they consider to be “in memory” are actually residing in physical memory, and not sitting in a swapfile somewhere.
So typically, on a large database system the vendor recommendation will be to set
vm.swappiness=0to minimize memory pressure from filesystem caching, and to set the database buffers as high as the amount of memory you have in your system minus a small amount for the operating system.