Subject: Re: JFS
To: Pavel Cahyna <>
From: Christoph Hellwig <>
List: tech-kern
Date: 02/24/2003 22:05:39
On Mon, Feb 24, 2003 at 08:32:10PM +0100, Pavel Cahyna wrote:
> I believe that the realtime behaviour or Guaranteed Rate I/O 
> (are you speaking about this?)
> is an option which you may or may not have. If you want it, you must enable
> it at the filesystem's creation date (a so-called realtime subvolume
> must be added, which AFAIK should reside on a separate disk) and I
> believe you also must purchase it separately (not sure about this). Linux's
> XFS doesn't even have this option. So XFS could (theoretically) be
> ported without it.

XFS/Linux does have (mostly untested and unsupported) support for realtime
subvolumes, it's the CONFIG_XFS_RT built option.  XFS/Linux does currently
not have support for GRIO due to lack of support in the Linux block layer.

In Linux 2.5 there is ongoing work to support pluggable I/O schedulers so
and GRIO implementation may become doable.