I am troubleshooting NFS performance issues on Linux, and I'm looking at the following nfsiostat output:

host:/path mounted on /path:

   op/s   rpc bklog
  96.75      0.01
read:       ops/s        kB/s      kB/op    retrans    avg RTT (ms)    avg exe (ms)
           86.561    1408.294     16.269   0 (0.0%)     34.595          89.688
write:      ops/s        kB/s      kB/op    retrans    avg RTT (ms)    avg exe (ms)
           10.113     326.282     32.265   0 (0.0%)     19.688       72446.246

1. What exactly is the meaning of avg RTT (ms) and avg exe (ms)?
2. avg exe for writes is 72 seconds(!) -- would you say this is abnormal and, if so, how do I go about troubleshooting this further?

I'm using NFS over TCP. Both the client and the server are on the same GigE LAN.