Re: RT patch acceptance

Christoph Hellwig
2005-05-28T06:55:23Z

On Fri, May 27, 2005 at 04:36:45PM -0700, Bill Huey wrote:
> Now think about this. You're a single kernel engineer. You don't have
> the resources to make every kernel subsystems hard RT capable. You
> have this idea where you'd like get at SGI's XFS's homogenous object
> storage to stream video data with guaranteed IO rates. This needs to
> be running in an RT domain so that guarantees can be tightly controlled
> since you're running an app that doing multipule file streaming of
> those objects. What kernel subsystems does this include ?
>
> It includes the VFS system, parts of the VM, all of the IO subsystems
> including SCSI/IDE and IO schedulers, etc..., the softirq subsystem
> supporting the SCSI layers and IO schedulers, all the parts of XFS
> itself. The list goes on.

You're on crack as usual, but today you go much too far. XFS doesn't
ahave anything to do with you're so Hard RT pipedreams. The so-called
'RT' subvolulme only provides a more determinitistic block allocator.
GRIO doesn't require any RT guarantees, it's entirely about I/O scheduling
and has been ported to various operating systems with sane locking semantics.