Re: [PATCH] libata: rewrite SCSI host scheme to be one per ATA host

[Jens Axboe]

On Wed, Apr 22 2009, Jeff Garzik wrote:
> Jeff Garzik wrote:
>> Currently, libata creates a Scsi_Host per port.  This was originally
>> done to leverage SCSI's infrastructure to arbitrate among master/slave
>> devices, but is not needed for most modern SATA controllers.   And I
>> _think_ it is not needed for master/slave if done properly, either.
>
> BTW note the above, with regards to the libata SCSI->block conversion.  
> libata currently relies on SCSI for some amount of generic device  
> arbitration, in several situations (see ->qc_defer,  
> SCSI_MLQUEUE_.*_BUSY).  libata expects SCSI to be intelligent and not  
> starve devices, etc.

Defer looks like internal policy, I don't see that functioning any
different in the block layer. SCSI_MLQUEUE_*_BUSY in SCSI is primarily
using the block layer functionality of BLKPREP_DEFER to begin with, so I
think we're pretty close to providing all that already.

-- 
Jens Axboe

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/