Last days, I start testing FreeBSD and OpenBSD. I think they are "new" interesting operating systems (to me), while I always face the same problem in all installations I made using FreeBSD or OpenBSD. After any Compilation memory don't shrink again, into some "value", below the "value", of Memory usage, when compilation was active.
You see, in all this tests, both BSD systems are using about 8GB of RAM, after the compilation ends. In fact the ZFS technology, can be useful for any administrator, while it really consume a lot of memory. I test the same with UFS and the result was the same. Memory don't lower, after compilation time. So, is not about the FileSystem, is about some other technical detail that I don't know what it is, while I suspect that can be Kernel Configurations that dictate that behavior, probably. Anyway, that behavior is not the default within BSD systems, while Debian and others, memory usage fall down into some "realistic" value of memory usage, since the compilation is over. But is a fact that, using Gentoo the value of memory-usage, after compilation, is more realistic. If I start a Gentoo server that is using 120M of Memory, after compiling anything(including gcc or clang), memory will lower until it is using 120M again. (cache is there, but is cached not active) We can always use the echo 3 > /proc/sys/vm/drop_caches to drop that used-memory, from memory.
There are some other distros that I need to test, since they are really minimal and that is what I am thinking to use, if using Qemu or Docker, where memory usage will grow and shrink, depending of software realtime activity, not based on it's history of activity, which is the sensation that BSD systems suffer from. While I must admit, that my own experience, I feel myself a bit like a BSD system, that have the memory of history, and cannot drop the cache, which can "create some problems". Sorry about that, but is what life it is, at the end of any illusional process that aims to create the product of that "dream" in reality.
I will probably give a change to OpenBSD to be a Firewall-Router, behind my ISP router, since PF rules are simpler (in my own perspective), than IPTables rules. Naturally this can be a false afirmation, since the simplicity, don't always care about details that make any rule, complex.
Maybe there are several ways to clean the active-memory of BSD systems after compilation ends, but I don't know how, and I don't found any results that save me time.