From: James Bottomley <James.Bottomley@SteelEye.com>
To: Jens Axboe <axboe@suse.de>
Cc: Alan Stern <stern@rowland.harvard.edu>,
Pat LaVarre <p.lavarre@ieee.org>,
SCSI development list <linux-scsi@vger.kernel.org>
Subject: Re: bytes/CDB of SCSI pass thru grossly limited maybe
Date: 28 Aug 2004 13:51:36 -0400 [thread overview]
Message-ID: <1093715498.3682.4.camel@mulgrave> (raw)
In-Reply-To: <20040828143124.GB2518@suse.de>
On Sat, 2004-08-28 at 10:31, Jens Axboe wrote:
> > usb-storage, for example, where the protocol only limits us to 4 GB per
> > transfer, there would be no problem allowing max_sectors to go as high as
> > 65535?
>
> If the hardware and driver can handle it, there's no other limit.
Actually, if you go through the SCSI stack, you're limited by our SG
list slot allocation which we use a mempool for. The default maximum is
128, although there's an option to increase this to 256.
These slots are the number of entries in the SG list we allow. If your
driver disables clustering, and you havea no IOMMU, this limits you to
128*<page size> = 512kb on x86 bytes. Otherwise, it can go higher
depending on the HW capabilities. Remember too that a lot of HW limits
the number of SG slots (see the sg_tablesize entry for each driver).
James
next prev parent reply other threads:[~2004-08-28 17:51 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <A8E06BE4-F7BA-11D8-AC6B-00039398BB5E@ieee.org>
[not found] ` <Pine.LNX.4.44L0 .0408271100590.1238-100000@ida.rowland.org>
2004-08-27 15:09 ` bytes/CDB of SCSI pass thru grossly limited maybe Alan Stern
2004-08-28 14:31 ` Jens Axboe
2004-08-28 15:14 ` Alan Stern
2004-08-28 15:36 ` Jens Axboe
2004-08-28 17:51 ` James Bottomley [this message]
2004-08-28 17:55 ` Jens Axboe
2004-08-28 18:20 ` James Bottomley
2004-08-28 18:41 ` Jens Axboe
2004-08-29 13:34 ` James Bottomley
2004-08-29 13:45 ` Jens Axboe
2004-08-30 18:15 ` Pat LaVarre
2004-09-01 15:20 ` Pat LaVarre
2004-07-30 23:04 Pat LaVarre
2004-07-31 14:12 ` Jens Axboe
2004-08-16 17:55 ` Pat LaVarre
2004-08-17 18:07 ` Pat LaVarre
2004-08-23 15:46 ` Jens Axboe
2004-08-23 16:05 ` Pat LaVarre
2004-08-23 17:08 ` Jens Axboe
2004-08-23 17:28 ` Pat LaVarre
2004-08-23 18:17 ` Jens Axboe
2004-08-26 23:20 ` Pat LaVarre
2004-08-23 16:06 ` Jeff Garzik
2004-08-23 17:05 ` Pat LaVarre
2004-08-23 18:48 ` Luben Tuikov
2004-08-23 19:06 ` Jeff Garzik
2004-08-23 19:14 ` Luben Tuikov
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=1093715498.3682.4.camel@mulgrave \
--to=james.bottomley@steeleye.com \
--cc=axboe@suse.de \
--cc=linux-scsi@vger.kernel.org \
--cc=p.lavarre@ieee.org \
--cc=stern@rowland.harvard.edu \
/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).