WSREP: Failed to report last committed

Errors:
[Warning] WSREP: Failed to report last committed 4277187, -4 (Interrupted system call)
[Warning] WSREP: Failed to report last committed 4277393, -4 (Interrupted system call)

Environment:
Server version: 5.6.28-76.1-56-log Percona XtraDB Cluster (GPL), Release rel76.1, Revision f9b078d, WSREP version 25.14, wsrep_25.14
6 Node cluster
CentOS release 6.7 (Final)

We are constantly bombarded with the above warnings though this
https://www.percona.com/blog/2016/05/27/galera-error-failed-to-report-last-committed-interrupted-system-call/
link says its warning and ignorable we are seeing slowness in the cluster and its not behaving as expected meaning the nodes are not responding, slowness.

Will you be able to confirm if this is an bug or any configuration setting that needs to be tweaked ?.

Any help would be appreciate on this.

-Ilan