Sluggish scheduling during a long disk copy

[Kris Kennaway]

Dan wrote:
> Kris Kennaway(kris at FreeBSD.org)@2008.11.09 12:57:16 -0800:
>>> could be an issue with ntfs-3g driver
>> Sounds like it to me.  ntfs-3g uses FUSE, which is a userland filesystem  
>> framework.  By design it will have poor I/O performance since every I/O  
>> transfer will require multiple trips into and out of the kernel.
> 
> The FS performance isn't the issue, the poor interactive performance is.

If you're thrashing your system with too many context switches or I/O 
load it is expected that performance will suffer.  You should do some 
additional investigation with the standard monitoring tools (top, 
vmstat, gstat, etc) to determine what your system is doing.

Kris