Explaining top(1) on FreeBSD | Hacker News Reader

Explaining top(1) on FreeBSD

klarasystems.com

71 pointsvermaden11 comments

Off topic question: what's the current process to make extremely small "minimal" freebsd server install? Is it NanoBSD[1], because the unfortunate downside is that the base can't change (I realize that's a feature) and for a web server or database server that might not be ideal.

[1] https://docs.freebsd.org/en/articles/nanobsd/

If you're building from source, then I'd just disable what you don't need via src.conf(5)'s various WITHOUT_FOO settings. They are described in the man page itself.

I did this a while ago. the .iso.xz came in at 22.1 MB and the .iso at ~80MB.

That's for a ro image with tmpmfs and varmfs[0], a minimal kernel, base and the packages nginx-lite, jansson, re2, curl, acme.sh and some services.

The system boots from an ISO into running nginx and hosting a basic network scanner[1] at a VPS provider.

I basically built from source with a custom SRCCONF[2], KERNCONF[3] and some other cleanup[4].

There may be easier ways to do it but it worked out pretty well for me.

[0] https://www.freebsd.org/cgi/man.cgi?rc.conf(5) [1] https://disco1.sajber.se/ [2] https://github.com/sebcat/yans/blob/master/tools/freebsd/vm/... [3] https://github.com/sebcat/yans/blob/master/tools/freebsd/vm/... [4] https://github.com/sebcat/yans/blob/master/tools/freebsd/vm/...

You may be asking for something different, but FreeBSD Jails can be extremely small, even down to just a single process[0][1].

[0] https://docs.freebsd.org/en/books/handbook/jails/

[1] https://gist.github.com/hiway/2b526fc64748e8d6e9f36f289003f8...

This may not be the answer you are looking for, but OccamBSD seems to be a way to produce a minimal image for use in FreeBSD jails, FreeBSD bhyve and Xen: https://github.com/michaeldexter/occambsd

> The topic of load average is generally very broad and it is calculated differently on various UNIX systems, so a separate article may be dedicated for just that.

I have never seen an article explaining how the load average in Linux is calculated.

The traffic analogy is a good explanation. Here you go: https://scoutapm.com/blog/understanding-load-averages

Tangentially related: modern kernels have a much better metric (PSI, or pressure stall information)

https://lwn.net/Articles/759781/

https://lwn.net/Articles/775971/

Well, that's still an aggregated value that someone decided to calculate based on what they thought would work best for what they're looking for. It's not necessarily more a correct definition of load, just one that is more appropriately actionable for the problems it's designed for.

In other words, PSI is "better" for some definition of "better".

One thing about load average on Linux which I never really understood was the inclusion of processes waiting for I/O, I never really got a satisfying explantation until I bumped into this post a few years ago: https://www.brendangregg.com/blog/2017-08-08/linux-load-aver...

“Examining Load Average” by Ray Walker:

https://www.linuxjournal.com/article/9001

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