Previous discussions: https://news.ycombinator.com/item?id=10654681 https://news.ycombinator.com/item?id=10652076
Wait a minute. I thought Netflix famously ran FreeBSD.
The CDN servers are basically appliances, and are often embedded in various data centers (includes those ran by ISP's) to aggressively cache content. They care about high throughput and run a single workload. Being able to fine tune the entire stack, right down to the TCP/IP implementation is very valuable in this case. Since they ship the hardware and software, they can tightly integrate the two.
By contrast, API workloads are very heterogeneous. I'd have to imagine the ability to run any standard Linux software there would also be a big plus. Linux clearly has much more vetting on cloud providers than FreeBSD as well.
tl;dw: the performance, the efficiency of development, the community, FreeBSD is a complete operating system, the code base is smaller, the ports system, and the license.
and this video covers the optimizations Netflix has made to FreeBSD: https://www.youtube.com/watch?v=36qZYL5RlgY
Also potentially a reason: According to drewg123, Linux's kTLS was broken. Which I see drewg123 also commenting in this thread. Is he the "Drew on my team" mentioned in the first video? Is he the speaker in the 2nd video? Idk https://news.ycombinator.com/item?id=28585008
I have pulled out a few miracles using these tools (identifying kernel bottlenecks or profiling programs using ebpf) and it has been well worth the investment to read through the books.
People thought I was a wizard lol.
There is no shorter command to show uptime, load averages (1/5/15 minutes), logged in users. Essential for quick system health checks!
You always want the load average to be less than the total number of CPU cores. If higher, you're likely experiencing a lot of waits and context switching.
[1] https://www.brendangregg.com/blog/2017-08-08/linux-load-aver...
Note that synchronous I/O completion checks for previously submitted asynchronous I/Os (both with libaio and io_uring) do not contribute to system load as they sleep in the interruptible sleep (S) mode.
That's why I tend to break down the system load (demand) by the sleep type, system call and wchan/kernel stack location when possible. I've written about the techniques and one extreme scenario ("system load in thousands, little CPU usage") here:
https://tanelpoder.com/posts/high-system-load-low-cpu-utiliz...
What is a 'good load' depends on the application and how it works. Some servers something close to 0 is a good thing. Other servers a 10 or lower means something is seriously wrong.
Of course if you don't know what is a 'good' number or you are trying to optimize a application and looking for bottlenecks then it is time to reach for different tools.
https://nicolargo.github.io/glances/
I have also hacked basic top to add database login details to server processes.
Especially SSDs are treated like magic storage devices with infinite IOPS at Planck-scale latency.
Until you discover that SSDs that can do 10GB/s don't do nearly so well (not even close) when you access them in a single thread with random IOPS, with queue depth of 1.
I always use a configured!(F2) htop (not mentioned as well). Always enable PSI information in htop (some red hat systems I work with still don't offer them...).
If you have zfs enable those meters as well and htop has an io tab, use it!
It is excellent and contains most things you could need. Downside is that it isn't yet a standard tool so you need to get it installed across your fleet
$ free -m
total used free shared buff/cache available
Mem: 3915 2116 1288 41 769 1799
Swap: 974 0 974Linux Performance Analysis in 60,000 Milliseconds - https://news.ycombinator.com/item?id=10652076 - Nov 2015 (11 comments)
Linux Performance Analysis - https://news.ycombinator.com/item?id=10654681 - Dec 2015 (82 comments)
Linux Performance Analysis in 60k Milliseconds (2015) [pdf] - https://news.ycombinator.com/item?id=44070741 - May 2025 (1 comment)
emmelaich•14h ago
mmh0000•10h ago
Today, you'd want something like:
Prometheus + Node Exporter [1]
[1] https://github.com/prometheus/node_exporter