What's the right amount of swap space for a modern Linux system?

Interesting that most voters on the page believes that zero swap is a good thing. Taking a quick look at my own servers and desktop usage it fits perfectly in table 2, ie. the same as the authors and Fedora's recommendation.

In what situation would you be 100 % sure you could never run out of RAM or would rather have an OOM situation than using swap? Seems extremely counter-intuitive to me.

These estimates are bizarrely high, in my experience.

Laptop: RAM + 1GB.

Laptops hibernate, and they need space for that. The extra gig is for temp space during the hibernate/restore time periods.

Desktop: 1GB.

Linux will often use some swap space when available for libraries which are technically loaded into memory but will never actually be called again. This is typically in the 100-300MB range.

Server: minimum 1GB -> 1/16 RAM -> maximum 8GB

Servers shouldn't swap; as soon as they do, you should either be adding more RAM or figuring out what went wrong. In the meantime, a little swap will let you ride out a short storm. If you're actively swapping on 8GB of RAM, you have a more serious problem anyway.

Assume that these numbers will change, mostly under the impact of new storage technology. SSD made swapping much less nasty for the system's performance, but at a more serious cost to the storage's lifetime.

I'd like to see some differentiation between a server and a desktop, since the correct answer varies wildly.

On app servers I'll often do no swap because I don't want the performance hit of an unexpected swap. I have real time memory monitoring and self-healing in place to prevent OOM. On a bastion server that isn't handling user traffic I probably will add a swap so I can get by with lower total memory on the box, and have a buffer before the OOM killer starts hacking away.

On desktop I'll often have a large swap that's there mostly so I don't get to that horrible locking hell when the OOM killer starts mercilessly hacking processes I care about while leaving ones I don't alive. This gives me time to handle it myself. Also I may want to hibernate.

So tl;dr: the rules all change depending on what the box is used for. Asking this question generally is like saying, "what should the towing capacity of my car/truck be?" Well the next question is: what are you towing? do you care about fuel efficiency, etc.

My 8gig ram linux system runs out of ram and sometimes crashes when I run Android Studio. It refuses to use the default swap file on the ssd hard drive.I created a 16 gig swap file and set the swappiness value to 100. It only uses a few megabytes of the swapfile sometimes and still runs out of memory when I run Android Studio and then crashes. I ordered 16 gig ddr4 ram today and will remove the current swap file when the ram arrives. Seems like the only solution. I don't have time to burn another night reading up on this.

The 'right' answer is to stop allocating swap in a separate partition, and share swap space with the filesystem.

Whether you do this with an LVM, or by pinning files and swapping to their underlying extents is less important. But assuming at system setup time that you can bound the amount of swap that will be required in the future to support some specific workload is silly, and in order to avoid being wrong, you have to penalise most systems most of the time.

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