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I just did the graphic
I basically never used swap until I used some script that was supposed to de-duplicate text messages from SMS backups.
Turns out feeding it a 100,000 message archive spanning back 15 years will somehow eat up ~80GB of RAM. I doubt it should, I guess it probably just wasn't optimized for such a large amount.
So I made a 64GB swap file and it completed fine.
Not everything should work from ram. This is why we stream files for processing.
The backup itself was only ~8gb.
The trick is to first create a RAM disk. Then put the swap file on there and it's about as fast as RAM. Then, with the new memory you have created, make another RAM disk. Yep, then make more swap space on there.
I have solved both the memory and SSD availability issues with this infinite RAM and disk space trick.
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).
ACPI S4 Hibernation would like to have a word with you
"I'm not a friggin bear, I don't hibernate!"
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.
Everyone defending swap like crazy in the comments... so let me give a counter argument specifically for desktop:
Many years ago I stopped using swap on all my computers (I exclusively use linux) and the reason is: every time anything regarding interactivity went to swap, my system would freeze and literally become unusable for a really long time until I killed something. Since I got tired if that behaviour I decided I prefer for random shit to die but my computer still be usable.
It wasn't very often, but I don't get OOM killer often either (as in I don't remember the last time it happened and I use linux every day for both work and fun), and the freezing situation was way more annoying, to the point I sometimes ended up cold switching off the computer. I'm surprised on how many people run out of memory constantly. I guess you all are just using linux for servers and have crazy processing of infinite data...
Were you using a HDD for swap? It's nearly unnoticeable on an NVMe drive.
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.
Swappiness set to over 9000!
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 swapon commands.
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)
Because you just taught your computer how to be lazy. "oH lOoK aT mE i'M sWaP mEmOrY"
Swap and zram saved my R and Python Dana analysis script a couple of times.
Swap is there an emergency relief for when a runaway process starts to eat all the resources. The system gets slow the user says hey what's that? They look and see oh wow this one process is really eating a lot of resources that's bad, can I kill it or do I need to gracefully try to shut it down. Swap buys you time when it could matter. When you don't have swap OOM killer takes out whatever it wants and for a desktop user that may not be that big of a deal but for a server the database is likely the first target that is taken out.
you misunderstand the meme (of course it doesn't help either); because the alternative isn't "no swap", but rather "use a swap file instead of swap partition"
Hrmm. How does that change the SSD problem if you are using a file on the SSD? I reread the meme. Maybe I'm too blurry eyed still but I don't see that coming through.
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.
Thatβs 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. Hereβs 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
I don't really need swap until I need to compile blender... Need somewhere around 64Gb (with compression) to deal with the peaks
ZFS chuckles darkly in the corner
I dislike swap solely because it gets used and when I accidentally open the same file twice then I regularly encounter problems with swap files when opening the file again later.
Your problem is not caused by system swap.
I know but I encounter the word swap only there and its annoying
My 64GiB are enough for my tasks, i don't use swap.
I may consider it for laptops but only for hibernation purposes.
unfortunately with S0ix being forced on all modern laptops, zram is the only logical choice. With s3 sleep at least i can say i need swap because i need hibernation...With S0ix? Dont bother.