I just did the graphic
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ACPI S4 Hibernation would like to have a word with you
My 64GiB are enough for my tasks, i don’t use swap.
I may consider it for laptops but only for hibernation purposes.Once tortured myself with having to go through…
The Android build system. Booo, scary.
I only wanted a LineageOS boot image built. The recommended specs list 64GiB RAM. Figured wouldn’t apply to me until I tried to build a target literally called “nothing”. It just used up all of the RAM and OOMed about 2 minutes in, building the “build cache” or whatever the fuck it needs to do to “warm up”.
After a few fucktons of swapspace, turning off some of my daemons, some sysctl fuckery (there were options for limiting process virtual memory size IIRC? I put it all the way up) and
taskset -p 0-15:1(use logical CPUs 0, 2, 4…), I had my laptop allocating 50 something GiB. I have 16GB (decimal) physical RAM installed and I consider that already way too much for my usual needs.After about half an hour of the build system build systeming, it just stopped doing that then built the kernel in 4 minutes with everything else in some time too.
Yes, I have tried just running make directly. That just resulted in an image that did nothing but toggle on and off an empty (no percentage) charging circle via power button.
There are good use cases for swap. I work with very performance sensitive memory hogging applications that tend to process in bursts as incoming batched data arrives. We also have a lot of required background “security” applications.
Having the idle applications move out to swap so that a significant amount of free RAM to allow for the active, real-time applications to expand into is a major boon. RAM is expensive now, so it’s become even more critical to not waste it.
But even in self-hosting at home I take advantage of it since I have a limited number of servers with limited RAM and a bunch of applications and/or docker containers running, many of which don’t need to be active at all times, but if they were all active, would have trouble with the limited RAM. Swap allows for inactive applications to free up RAM for the active ones and leave enough available at all times to allow an application to quickly spin up new jobs.
Anyway, sure, for a simple desktop computer without a bunch of junk background applications running for “security” or whatever, and an overabundance of RAM installed, it’s probably not useful. But for high performance, memory hungry applications with lots of background stuff running, it can be a big help.
That said, there are use cases where the opposite is useful and using a RAM drive is better than writing to disk for cache and temporary logs when you have enough RAM. My opnsense router for instance uses a RAM drive to store cache and logs (logs are mirrored to the NAS for long term storage, so just the local copy is lost on reboot). That system has enough RAM and I’d rather reduce disk wear, and I don’t plan to add too many other applications to that server that it would run low.
Actually, there are more than these. For example, hibernation and/or hybrid suspension. It’s, AFAIK, mandatory to have a swap partition to be able to hibernate and/or hybrid suspend your device.
Its a meme built on stuff like this:
https://gist.github.com/joshenders/c4960cec9c63a7b7d68ffa9543356c43
I also found it useful to do some one-off batch processing of a big file without thinking of chunking and doing too complicated things. Imagine something like a 60GB file in a custom format that need to be deduplicated. It’s easier to just load it all up in memory and do run the algorithm 2-3x slower using a 50GB swapfile than spend hours to complicate the algorithm.
Yep. That’s why it can be nice to just have like an old 1TB drive completely used for swap. Things might get slow once it exceeds your physical memory, but at least it will eventually finish successfully – no out of memory crashes here!
Maybe stop giving a shit what I do with my partions? 🤷 Mine is definitely to try and make hibernate work on a shitty old laptop that’ll drain the battery if I let it sleep and unplug it.
I was thinking about hibernation as well but wasn’t sure if hibernation might also work with a swap file
Honestly the kernel is smart enough to only use it if you need it most of the time from what I can remember from my admin days, no idea why op cares.
And here I am using swap for my self hosted services, some of which use ridiculous amount of ram.
OMG I miss this meme format
Have a PC with 16gb ram that lives up to the overwatch game system reqs. When I installed it and launched it, it began building some sort of cache. A one time job. During that chache my os would force close steam to prevent an oom crash. I then added 16gb swap and during the owerwatch cache job the used phys ram would max out at 12gb I think and the swap sent up to 10gb. So a 22gb ram job. Yikes. Thanks swap ram 👍
“I’m not a friggin bear, I don’t hibernate!”
Swap and zram saved my R and Python Dana analysis script a couple of times.
Can anyone tell me why I see swap usage with 10+GB of free RAM available?
Saving ram to swap can be done with minimal impact. Helpful when you run out of memory and that 2gb app idling can be dumped right away instead of waiting for it to be copied to swap.
but that’s not what’s happening. processes do actually get removed from RAM, and when they are needed they are very slow until they are loaded back. the system thinks it’s more valuable to have that memory be filesystem cache
If true then Linux is a decade behind windows and macOS.
tbh windows 10 was doing this very aggressively on my system, it was swapping like a mad man right when memory usage reached 50%
Doubt. It might be copying to swap, but not reading from it.
Swappiness set to over 9000!
Because you just taught your computer how to be lazy. “oH lOoK aT mE i’M sWaP mEmOrY”
If you(or your distro) use zram then the zram usage may also count as swap in resource monitors. For me this was the case when i saw swap usage where it is clearly not needed to swap. You can check it with
swaponcommands.Other reason is that more frequently accesed files may be cached to ram and less important stuff gets swapped. But if you notice swap being used while total ram usage including cached is much lower than total, then its probably zram(and it does write to disk so dont worry about that)
My built-in Devil’s Advocate has to ask if that’s really true? Have you got a citation newer than 2 decades old? Frankly, i find it difficult to believe that anyone wouldn’t like to use electron software, for the simple reason that making your SSD suffer is fun.
Edit: in 30 years of administering Linux and (previously) Solaris sytems i’ve never once had to change HDDs or SSDs, so claims of torture are, i opine, exaggerated. i’ll also claim that keeping electron software out of the filesystem is not good for your hygiene.
That’s some really great luck you have, over the 15 years or so I have been running my Linux server I have had to replace the SSD twice(likely due to gentoo and compiling everything all the time) and had 2 hdds in my raid cluster need replacement. Here’s hoping my NAS has your luck
To be clear: what i wrote is not actually something real, it was a joke i made by modifying a comment from a thread on github gist, i am actually surprised it wad credible enough that someone would reply seriously xD
https://gist.github.com/joshenders/c4960cec9c63a7b7d68ffa9543356c43
Definitely bit the onion on this one, it did seem remarkable lol though I just pulled a 16 year old drive out of my Son’s PC(that was technically still working however slowly) hence the semi plausibility on my end lol
lmao, 16 years is a lot! That drive can drive
Yeah it was to the point that Samsung doesn’t even admit to have made this drive on their website anywhere, I pulled the drive and was like wtf Samsung rust? I almost exclusively bought western digital in recent memory so was a surprise, had to do some digging to decode the manufacturing codes to identify the manufacturing date
I manage a cluster that makes heavy use of SSDs in RAID10 configuration. Those things are constantly degrading and having to be swapped out. I’ve started a drawer of faulted drives that I don’t have the heart you throw out.
Also, while Linux does run without Swap, it’s like running gears without grease.
“Unresizeable block device at end of disk”
Classically the swap partition was located at the physical middle of the drive so that on average, no matter where the heads where, the swap partition wasn’t far away
Also “unresizeable” as if you can’t just swapoff and just delete and recreated it anywhere (update the path in fstab) and then swapon again.
“Hello I would like to torture my SSD’s FTL because I left three Electron apps open”
If you don’t actually need the swap, Linux isn’t going to make use of swap. If you need the swap, then you’d probably rather use it than have the OOM killer take out a process.
My desktop has plenty of swap available, but is using none of it, because the system isn’t under memory pressure.
If you don’t actually need the swap, Linux isn’t going to make use of swap.
Eh, yes and no.
It will offload things from RAM into swap in order free up RAM space for disk cache. Which is kind of a weird reversal when you think about it, loading your RAM contents onto disk so that you can load your disk contents onto RAM. But by doing this to idle processes in order to disk cache files you’re likely to use soon, the system does become significantly faster and more responsive.
SWAP RAM is useful for hibernation mode and fall back ram incase you have low memory.
Also for when you, for whatever reason, run out of physical memory.
Who here worries torturing their SSDs? Those things will last lifetimes compared to HDD’s of the past (or present).
