All right, I am doing tests right now, but as far as I can see the 3.4.0-030400-generic kernel has the same behaviour as stock ubuntu 12.04.
With ubuntu server and this 3.4 kernel: Test: - all workstation writing a separate 4GB file with `dd´ to /testhome, which is nfs4 mounted from an ubuntu server 12.04. Result: - all other processes started on the same machine, that want to read or write to the same mountpoint, after this dd began just block. for instance: ls just waits until dd is finished. commandline completion never finishes and the shell just blocks. - load on the server goes beyond 90, and nfs kernel threads consume lots of cpu. There is also a lot of io waiting, which is to be expected. - Also the nfs kernel threads are unevenly loaded it seems. There is a bunch (10-20) which use about 20-30%, and it tapers off to 3-0.5%. With RHEL6 server: Test: - same test, but to /data/misc, mounted nfs4 from redhat 6.3 server. Result: - processes started after dd began, wanting to read or write to the same mountpoint (/data/misc) block a few seconds but then start. for instance: ls waits for 5-6 seconds and then just answers. commandline completion waits about the same time and then completes the command or whatever it completes. - load on the server is also over 90, but the nfs kernel threads consume not so much cpu. Lots of io waiting. - nfs kernel threads are very evenly loaded. I see a long list of them using about 3% each. It goes up to maybe 5% and down to about 2%, and some of the 128 available threads are unused. I think more than half of them are active during the test. Keep in mind that this is a pretty heavy test (well I think it is anyway). But the ubuntu server already had big problems when the nfs usage is normal. Normal in our case means: - some people editing a few text files - a lot of people using web or mail, and therefore their firefox cache and the mail server accesses nfs-mounted /home/$USER/Maildir - some people doing heavy calculations and writing either a lot of small files or a few big ones. Small means about 1MB, big means several GB. -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1006446 Title: nfs4 causes enormous load in ubuntu-server making it unusable To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1006446/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs