Absolutely can and will take action. Doesn’t always kill the right process (sometimes it kills big database engines for the crime of existing), but usually gives me enough headroom to SSH back in and fix it myself.
I have limited experience with Linux, but why is it that when my system locks up, SSH still tends to work and let me fix things remotely? Like, if the system isn’t locked up, let me fix it right here and now and give me back control, if it is locked up, how is SSH working to help me?
So that’s the nifty thing about Unix is that stuff like this works- when you say “locked up”, I’m assuming you refer to logging in to a graphical environment, like Gnome, KDE, XFCE, etc. To an extent, this can even apply to some heavy server processes: just replace most of the references to graphical with application access.
Even lightweight graphical environments can take a decent amount of muscle to run, or else they lag. Plus even at a low level, they have to constantly redraw the cursor as you move it around the screen.
SSH and plain terminals (Ctrl-Alt-F#, what number is which varies by distro) take almost no resources to run: SSH/Getty (which are already running), a quick process call to the password system, then a shell like bash or zsh. A singular GUI application may take more standing RAM at idle than this entire stack. Also, if you’re out of disk space, the graphical stack may not be able to alive
So when you’re limited on resources, be it either by low spec system or a resource exhaustion issue, it takes almost no overhead to have an extra shell running. So it can squeeze into a tiny corner of what’s leftover on your resource-starved computer.
Additionally, from a user experience perspective, if you press a key and it takes a beat to show up, it doesn’t feel as bad as if it had taken the same beat for your cursor redraw to occur (which also burns extra CPU cycles you may not be able to spare)
Oh yes. I’ve had massive compiles (well linking) which failed because of the OOM killer, and I did exactly the same, massive swap so it will just keep going. So what if it’s using disk as RAM and unusable for a few hours in the middle of the night, at least it finishes!
It never kicks in for me when it should, but I figured out I can force trigger it manually with the magic SysRq key (Alt+SysRq+F, needs to be enabled first), which instantly recovers my system when it starts freezing from memory pressure.
Do note that this opens up a security hole. Since this can kill any app at random and is not interceptable, if you leave your PC in a public place, someone could come up and press this combo a few times. Chances are, it’ll kill whatever the locking app you’re using.
Yes. If you have swap the system will crawl to a halt before the process is killed though, SSDs are like a thousand times slower than RAM. Swapoff and allocate a ton of memory to see it in action.
Nvme PCIe 4 SSDs are quite fast now tho, you can get between DDR1 and DDR2 speeds from a modern SSDs. This is why Apple are using their SSDs as swap quite aggressively. I’m using a MacBook Pro with 16 GBs of RAM and my swap usage regularly goes past 20 GBs and I didn’t experience any slowdown during work.
Depends if the allocated memory is actively used or not. Some apps do not require a large amount of random access memory, and are totally fine with a small part of random access memory and a large part of not so random access and not so often used memory.
Alternatively I can imagine that MacOS simply has a damn good algorithm to determine what can be moved to swap and what cannot be moved to swap. They may also be using the SSD in SLC mode so that could contribute to the speedup as well.
Yes, it takes surprisingly long for the OOM killer to take action, but the system unfreezes. Just wait a few minutes and see whether that does the trick.
In a database course I took, the teacher told a story about a company that would take three days to insert a single order. Thing was, they were the sort of company that took in one or two orders every year. When it’s your whole revenue on the line, you want to make sure everything is correct. The relations in that database were checked to hell and back, and they didn’t care if it took a week.
Though that would have been in the 90s, so it’d go a lot faster now.
We have a company like that here somewhere. When they have one job a year, they have to reduce hours, if they have two, they are doing OK, and if they have three, they have to work overtime like mad. Don’t ask me what they are selling, though. It is big, runs on tracks, and fixes roads.
Hopefully that swap is on an SSD, otherwise that query may not ever finish lol
Once you’re deep into swap, things can get so slow that there’s no recovering from it.
Yeah it works surprisingly well. I installed Gentoo on a 2005 era laptop a few years ago and had to keep adding zswap until Rust could compile for Firefox. Iirc it took about 12G of zswap to get it working, but it wasn’t too bad overall.
The limiting factor is mostly your upload speed. And also you need to have a good QoS set up, or you have very limited internet usability. Where as on-site you can get way higher speeds for cheaper
I remember using ICMP data to bypass my high school’s firewall. TCP and UDP were very locked down, but they allowed pings. It was slow though - I think I managed to get a few KB per sec. Maybe there’s faster/fancier firewall bypass methods these days. This was back in the 2000s when an entire school would have a single OC-1 fiber connection.
For those too young to remember, the A:\ drive was for the hard 3" floppy disks and B:\ drive was for the soft 5.25" floppy disks. The C:\ drive was for the new HDDs that came out, and for whatever reason the C:\ drive became the standard after that.
Once upon a time, Google offered unlimited drive storage as part of some GSuite tiers. They stopped offering it a while ago and have kicked most/all legacy users off of it in the past few months. It was glorious while it lasted 😢
Guess they ran everyone out of business that they needed to, so now the premium features get yanked and your choice of alternatives is curtailed. Hooray for enshittification.
It’s not that, it’s that people were abusing it by using it for things like Plex with 100TB+ of data, which cost Google more than the revenue they got as a result. Blame the people that abused the policy. They’re not a charity and can’t keep an offer if they lose money as a result. Keep in mind that Google Drive data has several replicas and is also backed up to cold storage on LTO tapes, so people abusing the storage policy is actually pretty expensive for them .
They do still have unlimited data in some cases, for example with custom plans for large companies (like 50k+ employees).
At one point they offered unlimited storage for Play Music only. You could literally upload your entire collection. They changed it later to consume your Drive storage. Cheap enough plans so I subscribed. Then they killed off Play Music. I’m still salty about that.
They don’t to my knowledge, I believe that’s mounted through rclone which just usually sets the filesystem size to 1PB so that it doesn’t have to try to query what the actual limit is for the various providers (and your specific plan).
Agreed. This is especially bad, though, because if it’s compromised they basically have hardware-level access to your machine. Unless you’re using encrypted swap, and I’m not sure how standard that is.
Well, assuming you’ve already gone through the effort to write a custom kernel module to offload your swap pages to Google Drive, it doesn’t seem like that much of a stretch to have it encrypt the data before transmitting it.
Once we have super fast reliable internet we’ll likely have the whole computer as a service. We’ll just have access terminals basically and a subscription with a login, except for the nerds who want their own physical machine.
You have to know that some dinosaur at ibm is screaming about how they gave up the centralized computer and is salivating over gigabit fiber so he can charge everyone 15 bucks a month to use an ibm mainframe.
Stadia almost didn’t suck, I bet we’re 10 years from phones just being hand terminals that tap into a local server and desktops won’t be far behind.
I’m happy it happened and gave us up to book 6 on the little screen.
The show runners for both the syfy and Amazon seasons were the original writers, so everything is very true to their vision of the story. I’m only sad that they didn’t get to finish the final few books on television. The whole series is a Masterpiece of hard science fiction.
They’ve been reinvented repeatedly. Citrix, terminal servers, thin clients, cloud desktops, web apps, remote app delivery…
Most people (not necessarily here) need a web browser and an office program. Most people are well suited to terminals or something like a Chromebook.
I need actual hardware for my job and hobbies, but even I have a mini PC set up like a gaming console so that if I want to play games on my bedroom TV I don’t have to hook up my Steam Deck or gaming laptop. I just stream them.
Given the digital literacy of many “regular people” (e.g. my father, and seemingly every other of my friends), the idea is appealing. Especially, as most of them don’t care about privacy. Give them decent availability, and they will throw money at you. And if you also give them support, I will, too.
RAM as a service can’t happen. It’s just far too slow. The whole computer can though. It’s RAM can be local so it can access it quickly, then it just needs to stream the video over, which is relatively simple if creating some amount of latency to deal with.
It’ll never be fast enough. An SSD is orders of magnitude slower than RAM, which is orders of magnitude slower than cache. Internet speed is orders of magnitude slower than the slowest of hard drives, which is still way too slow to be used for anything that needs memory relatively soon.
A SATA SSD has ballpark 500MB/s, a 10g ethernet link 1250MB/s. Which means that it can indeed be faster to swap to the RAM of another box on the LAN that to your local SSD.
A Crucial P5 has a bit over 3GB/s but then there’s 25g ethernet. Let’s not speak of 400g direct attach.
modern NVMe SSDs have much more bandwidth than that, on the order of > 3GiB/s.
even an antique SATA SSD from 2009 will probably have much lower access latency than sending commands to a remote device over an ethernet link and waiting for a response
Show me an SSD with 50GB/s, it’d need a PCIe6x8 or PCIe5x16 connection. By the time you RAID your swap you should really be eyeing that SFP+ port. Or muse about PCIe cards with RAM on them.
My point was more that the SSD will likely have lower latency than an Ethernet link in any case, as you’ve got the extra delay of data having to traverse both the local and remote network stack, as well as any switches that may be in the way. Additionally, in order to deal with that bandwidth you’ll need to kit out not only the local machine, but also the remote one with expensive 400GbE hardware+transceivers, plus switches, and in order to actually store something the remote machine will also have to have either a ludicrous amount of RAM (resulting in a setup which is vastly more complex and expensive than the original RAIDed SSDs while offering presumably similar performance) or RAIDed SSD storage (which would put us right back at square one, but with extra latency). Maybe there’s something I’m missing here, but I fail to see how this could possibly be set up in a way which outperforms locally attached swap space.
SFP direct attach, you don’t need a switch or transcievers, only two QSFP-DD ports and a cable. Also this is a thought exercise not a budget meeting. Start out with “We have this dual socket EPYC system here with full 12TB memory and need to double that”. You have rolls dice 104 free PCIe5 lanes, go.
Bandwidth isn’t really most of the issue. It’s latency. It’s the amount of time from the CPU requesting a segment of memory to receiving it, which bandwidth doesn’t effect.
Yeah, but the point of RAM is fast random (the R in RAM) access times. There are ways to make slower memory work better for this by predicting what will be needed (grab a chunk of memory because accesses will probably need things with closer locality than pure random), but it can’t be fixed. Cloud memory is good for non-random storage or storage that isn’t time critical.
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