Re: [PATCH 0/2] convert libsas to the libata new eh

[James Bottomley <James.Bottomley@suse.de>]

On Wed, 2011-01-26 at 12:46 -0500, Jeff Garzik wrote:
> On 01/26/2011 09:08 AM, James Bottomley wrote:
> > I think better might be to move the eh thread functionality into block.
> > What libata really wants is one eh thread per phy.  It gets this by
> [...]
> > machinery, everyone should get what they want, and libata could dispense
> > with its current corruption of multiple SCSI hosts per physical bus
> > attachment.
> 
> That's not the whole picture.  libata originally chose one-host-per-port 
> because that winds up being the best queueing/queue-busy arrangement for 
> legacy IDE ports.

Right, but we count things at the lun, the target and the host.  For a
two level queue setup, you could use the target.

>   They behave quite similarly to independent 
> controllers -- even to the point of having separate irqs -- even though 
> multiple IDE ports are shoehorned into a single PCI device.

So interrupts don't really have much to do with the host, that's all
part of driver setup.  IDE is really just using the two lines as a
simple completion signal ... much like the current multi queue cards do
(which also have multiple interrupts per host).

James