hishamhm/htop — pull request #96 by crrodriguez (2014-05-19 22:56:13+00:00)
Title: Read kernel's "MemAvailable" if possible

Recent kernel versions support "MemAvailable" in /proc/meminfo
which provides more accurate information on the amount of memory
available. therefore we can now deduce:

usedmem = totalmem - MemAvailable;