Comment 36 for bug 1006446

I have been having a similar problem since upgrading my NFS server from natty to oneiric two weeks ago. When copying files over an nfs share to another oneiric machine, my transfers run smooth and quick. However when transferring files to any machine with an older distribution (I have one on natty and another on lucid), transfers will halt completely for about 30 seconds, then continue for a minute or two before halting again. I have tested with both nfs3 and nfs4 connections, and there is no difference in transfers.

Note that when transferring a single file from oneiric->oneiric that there are always a greater number of threads, but significantly lower cpu usage (compared to transferring to natty), and never any freezes during the transfer process.

NFS server info:
Oneiric 3.0.0-20-generic-pae
Dual-core Intel P4 3Ghz with 3GB ram

When transferring files to Natty client:
top - 11:04:39 up 9 days, 10:58, 2 users, load average: 0.49, 0.94, 1.25
Tasks: 199 total, 5 running, 152 sleeping, 0 stopped, 42 zombie
Cpu0 : 3.1%us, 42.3%sy, 0.0%ni, 54.5%id, 0.0%wa, 0.0%hi, 0.0%si, 0.0%st
Cpu1 : 13.2%us, 37.3%sy, 0.0%ni, 49.5%id, 0.0%wa, 0.0%hi, 0.0%si, 0.0%st
Mem: 2957484k total, 2771924k used, 185560k free, 26556k buffers
Swap: 1293196k total, 78112k used, 1215084k free, 2205876k cached

  PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
 2761 root 20 0 0 0 0 R 28 0.0 0:11.34 nfsd
 2767 root 20 0 0 0 0 S 26 0.0 0:15.31 nfsd
 2765 root 20 0 0 0 0 R 21 0.0 0:16.76 nfsd
 2766 root 20 0 0 0 0 R 20 0.0 0:15.88 nfsd

When transferring files to Oneiric client:
top - 11:14:20 up 9 days, 11:07, 2 users, load average: 0.14, 0.30, 0.77
Tasks: 200 total, 1 running, 156 sleeping, 0 stopped, 43 zombie
Cpu0 : 0.7%us, 6.0%sy, 0.0%ni, 84.3%id, 4.7%wa, 0.0%hi, 4.3%si, 0.0%st
Cpu1 : 0.3%us, 4.0%sy, 0.0%ni, 94.7%id, 1.0%wa, 0.0%hi, 0.0%si, 0.0%st
Mem: 2957484k total, 2767220k used, 190264k free, 28244k buffers
Swap: 1293196k total, 78088k used, 1215108k free, 2200132k cached

  PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
 2762 root 20 0 0 0 0 S 3 0.0 0:19.86 nfsd
 2765 root 20 0 0 0 0 S 3 0.0 0:25.06 nfsd
 2760 root 20 0 0 0 0 S 1 0.0 0:10.95 nfsd
 2761 root 20 0 0 0 0 S 1 0.0 0:20.20 nfsd
 2764 root 20 0 0 0 0 S 1 0.0 0:16.99 nfsd
 2766 root 20 0 0 0 0 S 1 0.0 0:25.58 nfsd
 2763 root 20 0 0 0 0 S 0 0.0 0:04.28 nfsd
 2767 root 20 0 0 0 0 S 0 0.0 0:26.92 nfsd