By default rsyslogd will run in kernel mode, when we have system that run in virtualization that does not support them, it will burden it's CPU.
I have system that run on virtuozzo virtualization system, since i install it until i found the solution of it, My CPU always run on 100%. I found the solution here it was changing the configuration. Here's the step :
$ service rsyslog stop
$ sed -i -e 's/^\$ModLoad imklog/#\$ModLoad imklog/g' /etc/rsyslog.conf
$ service rsyslog start