The prometheus_cadvisor container has high CPU usage. On various
production systems I checked it sits around 13-16% on controllers,
averaged over the prometheus 1m scrape interval. When viewed with top we
can see it is a bit spikey and can jump over 100%.
There are various bugs about this, but I found
https://github.com/google/cadvisor/issues/2523 which suggests reducing
the per-container housekeeping interval. This defaults to 1s, which
provides far greater granularity than we need with the default
prometheus scrape interval of 60s.
Reducing the housekeeping interval to 60s on a production controller
reduced the CPU usage from 13% to 3.5% average. This still seems high,
but is more reasonable.
Change-Id: I89c62a45b1f358aafadcc0317ce882f4609543e7
Closes-Bug: #2048223
97e5c0e9b1