Re: RFC: SCSI Generic version 4 interface

[Matthew Wilcox <matthew@wil.cx>]

On Wed, Nov 08, 2006 at 10:48:01AM -0600, Jeremy Linton wrote:
> 	A unified multiple device mmap buffer interface for would probably be useful 
> as well. This is to get around the problems inherent in the current design 
> that keep more than one device from using a mmap/reserve buffer allocated for 
> another device. 
> 	What I would personally like to be able to do with the SG interface is have a 
> shared memory region where I can kick off a few dozen tagged commands to a 
> device, get notification when they have completed and then send a similar 
> command to a second device, all without involving the CPU in any copy 
> operations, or too many page management operations.
> 	In my dream world this would require some kind of tagging of commands as well 
> so I don't have to handle a bunch of async completions for commands in a 
> group that need to complete as a group.

This is all starting to sound/feel a lot like the current proposed
design for netchannels: http://lwn.net/Articles/206699/

If we did an AF_SCSI (I've seen it mooted before), then I suppose we
could just use netchannels.

The other route is tweaking the current netchannels proposal to be a bit
less networking-centric and use kiocbs (or something ...) to hold the
data that's being transmitted.