Massive slowdown when re-querying large nfs dir

[Al Boldi <a1426z@gawab.com>]

There is a massive (3-18x) slowdown when re-querying a large nfs dir (2k+ 
entries) using a simple ls -l.

On 2.6.23 client and server running userland rpc.nfs.V2:
first  try: time -p ls -l <2k+ entry dir>  in ~2.5sec
more tries: time -p ls -l <2k+ entry dir>  in ~8sec

first  try: time -p ls -l <5k+ entry dir>  in ~9sec
more tries: time -p ls -l <5k+ entry dir>  in ~180sec

On 2.6.23 client and 2.4.31 server running userland rpc.nfs.V2:
first  try: time -p ls -l <2k+ entry dir>  in ~2.5sec
more tries: time -p ls -l <2k+ entry dir>  in ~7sec

first  try: time -p ls -l <5k+ entry dir>  in ~8sec
more tries: time -p ls -l <5k+ entry dir>  in ~43sec

Remounting the nfs-dir on the client resets the problem.

Any ideas?


Thanks!

--
Al