What does TCPRcvCoalesce, TCPAutoCorking and TCPHystartTrainCwnd in netstat mean?

We have some RHEL7 Apache reverse proxies that experienced a performance degradation event. After a few hours, restarting Apache restored performance to normal levels. We are trying to determine the root cause of the outage. During said investigation, I came across the following netstat numbers that I cannot find much documentation on: * TCPRcvCoalesce * TCPAutoCorking * TCPHystartTrainCwnd Anyone can explain what these stats mean? Are they indicative of any particular issue?