why runc always cost 40% cpu in k8s?

[zdyj3170101136]

I regularly collect the CPU consumption of all processes on the k8s machine through perf.

I found that the runc process usually consumes more than 40% of the CPU.

The following figure is a flame graph of the runc process on a k8s machine in the past minute。

it consist of 4000 different pid process of runc, cost 7.5 core.

here is the raw pprof file, you could use go tool pprof -http=: to open it
pprof.pb.gz

[lifubang]

Which runc version are you using, in your provided graph, I see intelrdt.getIntelRdtRoot, which has been removed from v1.1.0-rc.1.

[kolyshkin]

The pprof shown is definitely of the old version of runc, which used to parse /proc/self/mountinfo a lot (mostly for cgroups, but in this case it's for intel_rtd).

Over the last few years we've implemented a number of optimizations, it would be interesting to see if upgrading to runc 1.2 changes the picture you are seeing.

[kolyshkin]

@zdyj3170101136 are you going to keep participating in this?