NFSv3, ZFS, 10GE performance

[John Baldwin]

On Monday, March 26, 2012 1:03:42 pm Fabian Keil wrote:
> Bob Friesenhahn <bfriesen at simple.dallas.tx.us> wrote:
> 
> > On Mon, 26 Mar 2012, Sven Brandenburg wrote:
> > >
> > > Hopefully, readahead doesn't kill performance for smaller files.. :-)
> > 
> > You are right to be concerned.  There are plenty of cases where 
> > read-ahead damages application performance.  Reading data which is 
> > never actually used is expensive.
> > 
> > It would be useful if FreeBSD would support posix_fadvise() so that 
> > applications can specify the type of access they will use, and if this 
> > advice can be used by NFS and the filesystem layer to decide if 
> > read-ahead should be used, and how much.
> 
> posix_fadvise() is already available in FreeBSD 10.0-CURRENT.

It doesn't quite do the trick of bumping up the read ahead amount
for sequential yet (though that is an easy change).  Implementing
WILLNEED is a bit trickier as it requires per-FS support.  I have
patches to implement it for UFS.

-- 
John Baldwin