From: Jens Axboe <axboe@suse.de>
To: James Bottomley <James.Bottomley@steeleye.com>
Cc: torvalds@transmeta.com, Linux Kernel <linux-kernel@vger.kernel.org>
Subject: Re: [BK PATCHES] add ata scsi driver
Date: Mon, 26 May 2003 20:18:52 +0200 [thread overview]
Message-ID: <20030526181852.GL845@suse.de> (raw)
In-Reply-To: <1053972773.2298.177.camel@mulgrave>
On Mon, May 26 2003, James Bottomley wrote:
>
> On Mon, May 26 2003, Linus Torvalds wrote:
> > > What does the block layer need, that it doesn't have now?
> >
> > Exactly. I'd _love_ for people to really think about this.
>
> In discussion with Jeff, it seems most of what he wants is already
> there. He just doesn't know it yet :-)
>
> Maybe that's my problem as well, maybe the code / comments / doc /
> whatever is not clear enough.
>
> My wishlist for this would be:
>
> 1. Unified SG segment allocation. The SCSI layer currently has a
> mempool implementation to cope with this, is there a reason it can't
> become block generic?
Of course that is doable, when I killed scsi_dma.c it was just a direct
replacement. Given that IDE had no such dynamic sg list allocation
requirements, it stayed in SCSI. Overdesign is never good :)
> 2. Device locality awareness. Quite a bit of the esoteric SCSI queueing
> code occurs because we have two type of queue events:
> a. device can't accept another command---stop queue and restart when the
> device sends a completion back
This should be doable.
> b. the host adapter is out of resources for *all* its devices. Block
> all device queues until we free some resources (again, usually a
> returning command).
This is harder, because it involves more than one specific queue.
> 3. Perhaps some type of unified command handling. At the moment, we all
> seem to allocate DMA'able regions for our commands/taskfiles/whatever
> and attach them to reqest->special. Then we need to release them again
> before completing the request.
>
> 4. Same thing goes for sense buffers.
Completely agree.
> 5. There needs to be some amalgam of the SCSI code for dynamic tag
> command queue depth handling.
Again, block layer queueing was designed for what I needed (ide tcq) and
no overdesign was attempted. If you describe what you need, I'd be very
happy to oblige and add those bits. Some decent depth change handling, I
presume?
--
Jens Axboe
next prev parent reply other threads:[~2003-05-26 18:05 UTC|newest]
Thread overview: 68+ messages / expand[flat|nested] mbox.gz Atom feed top
2003-05-26 18:12 [BK PATCHES] add ata scsi driver James Bottomley
2003-05-26 18:18 ` Jens Axboe [this message]
2003-05-26 18:47 ` James Bottomley
2003-05-26 19:07 ` Jens Axboe
2003-05-26 19:17 ` James Bottomley
2003-05-26 19:33 ` Jens Axboe
2003-05-27 12:39 ` Jens Axboe
2003-05-27 14:26 ` James Bottomley
2003-05-27 17:16 ` Jens Axboe
2003-05-27 18:09 ` James Bottomley
2003-05-27 18:21 ` Jens Axboe
2003-05-27 18:30 ` James Bottomley
2003-05-26 20:27 ` Linus Torvalds
2003-05-26 20:36 ` James Bottomley
2003-05-26 20:45 ` Linus Torvalds
2003-05-26 20:51 ` Jens Axboe
2003-05-26 20:56 ` James Bottomley
2003-05-26 20:38 ` Jens Axboe
2003-05-26 20:49 ` Linus Torvalds
2003-05-26 20:57 ` Jens Axboe
2003-05-26 21:34 ` Linus Torvalds
2003-05-26 23:58 ` Nick Piggin
2003-05-27 0:09 ` Linus Torvalds
2003-05-27 0:49 ` Nick Piggin
2003-05-27 0:16 ` Alan Cox
2003-05-27 6:54 ` Jens Axboe
2003-05-27 14:20 ` James Bottomley
2003-05-27 14:36 ` Linus Torvalds
2003-05-27 14:59 ` James Bottomley
2003-05-27 15:21 ` Jeff Garzik
2003-05-27 15:38 ` James Bottomley
2003-05-27 15:50 ` Jeff Garzik
2003-05-27 16:00 ` James Bottomley
2003-05-27 16:16 ` Jeff Garzik
2003-05-28 9:35 ` Christoph Hellwig
2003-05-28 10:50 ` Lincoln Dale
2003-05-27 19:43 ` Jens Axboe
-- strict thread matches above, loose matches on Subject: below --
2003-05-26 4:58 Jeff Garzik
2003-05-26 5:15 ` Linus Torvalds
2003-05-26 5:30 ` Jeff Garzik
2003-05-26 5:36 ` Jeff Garzik
2003-05-26 5:42 ` Linus Torvalds
2003-05-26 6:01 ` Jeff Garzik
2003-05-26 16:56 ` Linus Torvalds
2003-05-26 17:47 ` Jeff Garzik
2003-05-26 20:09 ` Linus Torvalds
2003-05-27 0:29 ` Alan Cox
2003-05-27 6:07 ` Jeff Garzik
2003-05-27 6:30 ` Linus Torvalds
2003-05-27 6:51 ` Linus Torvalds
2003-05-27 7:29 ` Jeff Garzik
2003-05-26 5:40 ` Linus Torvalds
2003-05-26 5:53 ` Jeff Garzik
2003-05-26 6:21 ` Jeff Garzik
2003-05-26 16:57 ` Linus Torvalds
2003-05-26 17:24 ` Jens Axboe
2003-05-26 17:54 ` Jeff Garzik
2003-05-26 17:59 ` Jeff Garzik
2003-05-26 18:11 ` Jens Axboe
2003-05-27 0:22 ` Alan Cox
2003-05-27 4:15 ` Linus Torvalds
2003-05-26 10:32 ` Bartlomiej Zolnierkiewicz
2003-05-26 11:13 ` Jeff Garzik
2003-05-26 11:37 ` Bartlomiej Zolnierkiewicz
2003-05-26 5:59 ` Benjamin Herrenschmidt
2003-05-26 6:03 ` Jeff Garzik
2003-06-02 9:46 ` Andre Hedrick
2003-06-02 13:56 ` Alan Cox
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20030526181852.GL845@suse.de \
--to=axboe@suse.de \
--cc=James.Bottomley@steeleye.com \
--cc=linux-kernel@vger.kernel.org \
--cc=torvalds@transmeta.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).