Errors when running on Kops AMI or EKS

[Nuru]

Thank you for this utility!

When running on a Kops AMI (after running apt-get install libc-dev) I get errors like

sh: 1: cannot create /sys/devices/system/cpu/cpu0/cpufreq/scaling_governor: Directory nonexistent

There is a /sys/devices/system/cpu/cpufreq/ directory but not a per-cpu cpufreq directory. I would appreciate it if you would update the tool to take this into account. I'd offer a PR, but I don't understand the nuances of what you are doing to be sure of the right solution. Just deleting the cpu0/ part of the path did not solve the problem.

OS details:

# uname -a
Linux ip-10-105-15-150 4.9.0-9-amd64 #1 SMP Debian 4.9.168-1+deb9u5 (2019-08-11) x86_64 GNU/Linux
# cat /etc/os-release
PRETTY_NAME="Debian GNU/Linux 9 (stretch)"
NAME="Debian GNU/Linux"
VERSION_ID="9"
VERSION="9 (stretch)"
ID=debian
...

This also happens under Amazon's EKS:

# uname -a
Linux <redacted> 4.14.165-133.209.amzn2.x86_64 #1 SMP Sun Feb 9 00:21:30 UTC 2020 x86_64 x86_64 x86_64 GNU/Linux
# cat /etc/os-release
NAME="Amazon Linux"
VERSION="2"
ID="amzn"
ID_LIKE="centos rhel fedora"
VERSION_ID="2"
...

Also, what is a reasonable amount of throttling? I thought the Amazon AMI had the CFS scheduler patch (4.14.165 > 4.14.154 where the patch landed), but it was throttled as much as the Kops AMI.

[chiluk]

The script is attempting to set the CPU performance governor, which may not be available on AWS. Simply comment out the offending line. This script is intended to hit 100% throttling for the test 5000ms / 100 ms periods = 50 periods. A properly functioning kernel should see roughly

Throttled for: 51 CPU Usage (msecs) = 510

In both the single threaded ($ runfibtest 1) and in the multithreaded case ($ runfibtest).

This application wasn't really meant to handle all use cases, but more as a proof of failure to other kernel engineers. I will accept pull requests though.

[Nuru]

Unfortunately, without the offending code, I'm seeing the same behavior on the unpatched kernel where we are seeing throttling problems under Kubernetes, Debian 4.9.168-1+deb9u5 (2019-08-11):

Throttled for: 51 CPU Usage (msecs) = 511

as for the patched kernel, 4.14.165-133.209.amzn2.x86_64 #1 SMP Sun Feb 9 00:21:30 UTC 2020:

Throttled for: 51 CPU Usage (msecs) = 515

[Nuru]

@chiluk I forked this project intending to make a PR, but it seems like I may be hijacking your intent. What I have at Nuru/fibtest is strictly meant as a test for the "low cpu usage with high throttling" bug. The README no longer applies.

If you want it as a PR, let me know and I will contribute it. If you want me to release it as a separate project with a different name, please either change the license to the MIT license or give me explicit permission to make a derivative work without having to comply with section 4 of the Apache license. (I find section 4 really irritating for a project like this.)