From: Jens Axboe <jens.axboe@oracle.com>
To: Jeff Garzik <jeff@garzik.org>
Cc: linux-ide@vger.kernel.org, linux-scsi@vger.kernel.org,
LKML <linux-kernel@vger.kernel.org>, Tejun Heo <htejun@gmail.com>
Subject: Re: [PATCH] libata: rewrite SCSI host scheme to be one per ATA host
Date: Thu, 23 Apr 2009 08:35:42 +0200 [thread overview]
Message-ID: <20090423063542.GK4593@kernel.dk> (raw)
In-Reply-To: <49EEE225.3010700@garzik.org>
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
next prev parent reply other threads:[~2009-04-23 6:35 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-04-22 9:09 [PATCH] libata: rewrite SCSI host scheme to be one per ATA host Jeff Garzik
2009-04-22 9:23 ` Jeff Garzik
2009-04-22 12:16 ` Boaz Harrosh
2009-04-22 15:10 ` Daniela Engert
2009-04-22 15:18 ` Alan Cox
2009-04-22 15:37 ` James Bottomley
2009-04-22 16:27 ` Alan Cox
2009-04-22 18:36 ` Jeff Garzik
2009-04-22 19:27 ` James Bottomley
2009-04-22 16:48 ` Jeff Garzik
2009-04-23 6:35 ` Jens Axboe [this message]
2009-04-23 10:39 ` Jeff Garzik
2009-04-23 10:43 ` Jens Axboe
2009-04-22 13:09 ` Mark Lord
2009-04-22 16:52 ` Jeff Garzik
2009-04-22 19:08 ` Grant Grundler
2009-04-23 11:00 ` Jeff Garzik
2009-04-23 17:59 ` Grant Grundler
2009-04-23 18:09 ` James Bottomley
2009-04-24 11:00 ` Stefan Richter
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