> This means that, in general, vm.swappiness is simply a ratio of how costly reclaiming and refaulting anonymous memory is compared to file memory for your hardware and workload.

But I think this ignores the likelihood that I want this particular memory reclaimed. It is not equal for files and anon memory. At least on my systems, if anon memory is dirty, it's because I did something with it, and if I haven't freed it, that means I'm still working with it. But there's all sorts of stuff that just kind of ends up in the disk cache, which I will never touch again. It is irrelevant to me that refaulting a swapped anon page is no slower than rereading a file, because the probability that the first will happen is so much greater than the second.

For all that systems try to guess about which pages are in use, or will be used again soon, I find they pretty much all get it wrong and as a result the system gets janky, and it's best to simply weight keeping anon memory in core much higher. I expect disk access to be slow when I read a file. I do not expect ctrl-tab to be slow, ever.