Which component in PX SHOULD create csi.sock in /var/lib/kubelet/plugins/pxd.portworx.com/?

Portworx on Kubernetes
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Hi Portworx team
I have encountered a problem when I install PX in my own k8s cluster, the error log shows there is no csi.sock file. so I wonder which component in PX should create csi.sock in /var/lib/kubelet/plugins/pxd.portworx.com/.