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Comment by gpvos | Hacker News Reader

A swap file on a RAM disk seems... not useful.

Back in the dark ages I put swap on most of the graphics memory of an AGP bus graphics card. The read spead was slow compared to system RAM but insanely fast compared to swapping to HDD. Then put the graphics card as the highest priority swap so it swapped there before going to HDD.

How did you do that?

I don't remember, specifically I don't remember if I had to compile a tiny device driver to expose a chunk of RAM as a block device. In that case, it might have been something like this sample: https://www.opensourceforu.com/2012/02/device-drivers-disk-o...

There might also have been some way to convince the kernel a piece of RAM was a block device. The "ramdisk.c" driver in Linux was simpler before.

After that, it was a matter of creating an init script which formatted the block device as a swap device, then running swapon.

Depends on the system. I still use a ramdisk on my DOS/Win31/Win98 machine. It has lots of memory and Win98 crashes with more than ~768 MB RAM. I use the ramdisk to occupy excess memory.

What do you use the ramdisk for? That sounds pretty interesting.

swap and %TEMP%

You might find these interesting:

https://en.wikipedia.org/wiki/Zswap

https://en.wikipedia.org/wiki/Zram

If your RAM disk has a fixed size but there's some free space on it, and the system is out of RAM, it can effectively reclaim that otherwise unused space on the RAM disk at the cost of having to copy the pages back and forth.

from my vague memory, windows had a default minimum swap size. by putting it on to a RAM drive if you had enough memory (+ and as someone else mentioned compressing it as well) made things run much faster

Android does this with zram, and I think this is a big part of the reason why it tends to use more battery once you run low on RAM, since paging in and out requires (de)compression, which uses CPU.

Can be, if the RAM disk is compressed.

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