Linux Performance Analysis (2015) (netflixtechblog.com)

Nice list. sar/sysstat is underrated imho.

2015

Previous discussions: https://news.ycombinator.com/item?id=10654681 https://news.ycombinator.com/item?id=10652076

I quite like `iotop` as an alternative to iostat. https://linux.die.net/man/1/iotop

> At Netflix we have a massive EC2 Linux cloud

Wait a minute. I thought Netflix famously ran FreeBSD.

If you like this post, I would recommend “BPF Performance Tools” and “Systems Performance: Enterprise and the Cloud” by Brenden Gregg.

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.

he forgot about rusttop

My first command is always 'w'. And I always urge young engineers to do the same.

There is no shorter command to show uptime, load averages (1/5/15 minutes), logged in users. Essential for quick system health checks!

The iostat command has always been important to observe HDD/SDD latency numbers.

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.

it's 10 years later - what's the 60 second equivalent in 2025?

Maybe I missed it, but checking available disk space is often a good step in diagnosing misbehaving systems.

shameless plug: you can practice this in a free VM https://docs.sadservers.com/docs/scenario-guides/practical-l... (there's a typo there to keep you on your feet)

Almost all of these have been replaced for me with below: https://developers.facebook.com/blog/post/2021/09/21/below-t...

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

After this article was written, `free -m` on many systems started to have an "available" column that shows the sum of reclaimable and free memory. It's nicer than the "-/+" section shown in this old article.

  $ free -m
                 total        used        free      shared  buff/cache   available
  Mem:            3915        2116        1288          41         769        1799
  Swap:            974           0         974

Previously:

Linux 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)