High Kernel Load with nfsv4

[Loïc Blot]

Hi,
 i'm trying to create a virtualisation environment based on jails. Those jails are stored under a big ZFS pool on a FreeBSD 9.3 which export a NFSv4 volume. This NFSv4 volume was mounted on a big hypervisor (2 Xeon E5v3 + 128GB memory and 8 ports (but only 1 was used at this time).

 The problem is simple, my hypervisors runs 6 jails (used 1% cpu and 10GB RAM approximatively and less than 1MB bandwidth) and works fine at start but the system slows down and after 2-3 days become unusable. When i look at top command i see 80-100% on system and commands are very very slow. Many process are tagged with nfs_cl*.

 I saw that there are TSO issues with igb then i'm trying to disable it with sysctl but the situation wasn't solved.

 Someone has got ideas ? I can give you more informations if you need.

 Thanks in advance.
 Regards,

 Loïc Blot,
 UNIX Systems, Network and Security Engineer
 http://www.unix-experience.fr