Feature/optionally trust mem available

[rotdrop]

Optionally just use /proc/meminfo MemAvailable

MemTotal:       30773580 kB
MemFree:        10416436 kB
MemAvailable:   15917164 kB
Buffers:             124 kB
...

instead of computing an estimate based on buffers and cached pages.

[Tookmund]

Given the context as presented in the commit introducing MemAvailable I think it would make the most sense to simply detect the presence of MemAvailable and use it in preference to our own calculations instead of introducing another configuration option.

[rotdrop]

Given the context as presented in the commit introducing MemAvailable I think it would make the most sense to simply detect the presence of MemAvailable and use it in preference to our own calculations instead of introducing another configuration option.

Well, I tried to be kind to the rest of the code-basis ;) I can recode the patch accordingly, but I do not know when yet, I'll post any new suggestions here.

[Tookmund]

I appreciate you taking the least invasive approach first and bringing this feature to my attention!

This project simply doesn’t take advantage of a lot of features like this due to its age (pretty sure this didn’t exist when Swapspace was first written), and we’ve already had one known bug in our implementation: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=691128 Replacing it with a kernel-generated value seems like the best approach when it’s available, though I would like to retain the current calculations as a fallback.

[Tookmund]

A slightly-modified version of this PR has now been included in v1.18-beta2 60bfc53c42bfa5e9d8843abc96fb8c0e93ea5f11 There's still some testing and release management that needs to happen on my end, but once it's released I'll close this PR. Thanks for the patch!

[Tookmund]

Committed as 36384ee548cf749f75c5e5d85708030d63818918 and b206267f69188c6d106bbb2aef7ea90a9f871d2f