Sluggish scheduling during a long disk copy

[Bruce Cran]

On Sun, 09 Nov 2008 14:12:34 -0800
Kris Kennaway <kris at FreeBSD.org> wrote:

> 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.

It may be that FUSE is aggressively caching data and pushing your
applications out of memory.  This commonly happens on Linux and may
be happening here too.

-- 
Bruce Cran