What does DiskIOMetrics do?

Cluster information:

Kubernetes version: 1.20.13

Hi,

I would like to ask what does DiskIOMetrics do in kubernetes/pkg/kubelet/server/server.go at f3bfd08a118dcb02c1ff9bd3dd6437cb912f1d54 · kubernetes/kubernetes · GitHub

I have done some research and I am thinking this part of code is not used. The background of this question is we occasionally saw blkio is heavy on 4.15.0-72 linux servers and runc (rc10) exec command is slow on namespace_unlock.

Best,

Norman Shen