James Pearson wrote: > We have a number of identical NFS clients mounting a server using > NFSv4.1 - server and clients are all running CentOS 7.5 (kernel > 3.10.0-862.14.4.el7.x86_64) > > However, on some clients, the NFS performance 'degrades' with time ... > > Running a simple test - a python script that just imports a module > (python and its modules are installed on the NFS share) can be an order > of magnitude or more slower on some clients. i.e. very little data is > transferred, it is the rate of stat'ing and opening files on the NFS > server that is 'slow' > > Running a tcpdump on a 'slow' client shows that the NFS traffic > generated on the 'slow' client is again an order of magnitude or more when > compared with that generated by a 'fast' client > > The majority of the extra NFS traffic in the slow case, appears to be a > large number of NFS 'TEST_STATEID' calls the client makes - which are not > there in the tcpdump on the fast client > > The issue can be 'fixed' in the short term by rebooting the affected > client - and after a reboot, running the same tcpdump shows no TEST_STATEID > calls - however after a while (several days), the performance might > degrade again > > I've found a number of reports of excessive TEST_STATEID calls - but > most seem to relate to NFSv4 client hangs - which is not happening here - > things are working, but much slower than they should be ... > > Has anyone come across this issue - and have any fixes/workarounds? You might find some useful info in <http://www.admin-magazine.com/HPC/Articles/Useful-NFS-Options-for-Tuning-and-Management> On the other hand, we've had some issues, and on at least a couple servers, I've forced it to use 4.0 instead of 4.1, based on some information I found online, and it helped. mark