I have been noticing this problem as well. The Ubuntu domU ends up spinning on iowait with average sysload getting as high as 12! Any idea? This seems to be new behavior, I suspect an Ubuntu update caused it, but I don't know which one. Both read and write have been crippled with NFS. SMB/CIFS works significantly better. I'm moving performance sensitive files that don't need to be shared from the dom0 to mounts in the VM with "virsh attach-disk". That seems to be helping. I would like to fix the problem though. I believe there was an Ubuntu kernel update recently. Perhaps I should try the prior kernel.
Doing a "cp" to or from the NFS mount causes iowait to peg at 50% (2 CPUs in the VM) and causes NFS performance problems for other clients on the LAN. CPU and RAM are fine both in the dom0 and domU. Even "ls" is incredibly slow. The same operation with SMB/CIFS is significantly faster, doesn't leave iowait pegged high, and actually uses some CPU for the "cp" and SMB processes, while not causing the problems for other clients on the LAN. This is very strange as NFS used to be slightly more performant. I tried disabling ZIL with no change, not that I expected anything as zilstat was showing rather low ZIL usage. Ubuntu: Linux mythtv 2.6.31-20-server #58-Ubuntu SMP Fri Mar 12 05:40:05 UTC 2010 x86_64 GNU/Linux OpenSolaris b129. I've been holding on this build as it fixed the MPT errors I was having and the 2010.03 release was getting close. That's been delayed, but I haven't noticed any trouble until now. -- This message posted from opensolaris.org _______________________________________________ xen-discuss mailing list [email protected]
