Why use RAM disk when linux caches to RAM anyway?

[pletharoe]

Since Linux caches writes to RAM, you shouldn't need a RAM disk (assuming you're not doing any other IO). Or am I missing something?

[SebMoore]

The biggest issue is that the plotter reads a huge amount of data too, because it has to sort data and compress it. This means reads are a big problem, obviously, because the plotter doesn't constantly read the same file, so it can't be cached to ram. As such, the plotter has to keep going back to your ssd looking for files. Sure, maybe you could get a pseudo-ramdisk by increasing the time it takes to drop files out of the cache, but why not just use a regular ramdisk?

[madMAx43v3r]

If you have >384 GB RAM, then it works the same way yes. RAM disk just enforces the data which should be cached to be cached, reducing the amount of RAM needed to make it work.

[pletharoe]

Thanks, that's the answer I was looking for.

Now I just need to work out why it's only using 11 (ish) of my 128 threads.

[oleg-kn]

OS does not cache disk writes