I agree that there are specific cases where unusual amounts of swap are required. What I really object to is the use of formulas without understanding them or considering the implications. Myth based computing is a bad thing.

I second the “fart on excess swap use” sentiment!

You are correct to note that stuff which is unused is not a factor, but there is currently no support for having the amount of IO for swap be a factor in the OOM killer.

As for inactive programs in other workspaces, it’s a bit of a bummer when you switch sessions and suddenly your machine starts swapping without end.

If you have only a single memory hungry process then the correct amount of swap is determined entirely by that program.

The fact is that the 2*RAM advice is based on ancient versions of Unix and has never applied to Linux. I don’t believe that there is any cause to “tone down” any claims, merely to note exceptions to the general rule.

The fact that the right amount of swap for a system could be anything from nothing to 10X RAM is entirely irrelevant when considering the validity of the “use 2*RAM” advice which is bandied about by people who don’t understand the issues involved.

Obviously multi-user computers can afford to have lots of stuff in swap space without hurting performance, because some of those users (and their processes) may be inactive.

Similar comments apply even to single-user computers when running a graphical environment (X) where it’s easy to have many inactive programs in other workspaces.

For many systems, the question is moot, in that they never run out of memory even with little or no swap allocated.

My usage of memory-hogging programs is very different from most people’s, but, FWIW, I find that even if I have a single process whose virtual memory size is 2-3 times RAM size, then the system can still be responsive; it just depends on the memory access patterns of that program. Thus, I find that 2x is still about the right ratio for me for how big swap space should be compared to RAM, and in particular I’ve found that 1.5x is too small. Of course, other people’s needs may vary. All the same, I really suggest toning down the claims of the initial post.