From: Christoph Hellwig <hch@infradead.org>
To: Webb Scales <webbnh@hp.com>
Cc: Hannes Reinecke <hare@suse.de>,
James Bottomley <jbottomley@parallels.com>,
Christoph Hellwig <hch@infradead.org>,
linux-scsi@vger.kernel.org
Subject: Re: [PATCH] megaraid_sas: Enable shared tag map
Date: Wed, 1 Oct 2014 14:10:03 -0700 [thread overview]
Message-ID: <20141001211003.GA24820@infradead.org> (raw)
In-Reply-To: <542C4D33.2030401@hp.com>
On Wed, Oct 01, 2014 at 02:51:31PM -0400, Webb Scales wrote:
> Hannes,
>
> In megasas_change_queue_type(), is it possible for sdev->queue_depth to be
> greater than 256?
>
> Unless I'm misunderstanding the SCSI code, we can request a
> queue-depth/tag-map-size which is greater than 256, but, since the
> scsi_cmnd::tag field is an unsigned char, depths greater than 256 may
> overflow the field when high-numbered tags are used...do I have that right?
Yes, we really need to increase the size of the tag field. SAM allows
a transport specific limit of up to 64 _bytes_ for it, although I don't
know implementation that large. Given that the block layer can generate
up to 32-bit tags both for the old blk-tag.c code and the new
blk-mq-tag.c version it would be good to use a u32 there. Can you send
me a patch?
next prev parent reply other threads:[~2014-10-01 21:10 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-09-29 11:47 [PATCH] megaraid_sas: Enable shared tag map Hannes Reinecke
2014-09-29 16:52 ` Webb Scales
2014-09-29 17:08 ` James Bottomley
2014-09-30 7:43 ` Christoph Hellwig
2014-09-30 9:08 ` Hannes Reinecke
2014-10-01 18:51 ` Webb Scales
2014-10-01 21:10 ` Christoph Hellwig [this message]
2014-10-02 6:51 ` Hannes Reinecke
2014-10-02 9:19 ` Christoph Hellwig
2014-10-02 9:50 ` Hannes Reinecke
2014-10-02 11:36 ` Christoph Hellwig
2014-10-02 12:00 ` Hannes Reinecke
2014-10-02 14:32 ` Christoph Hellwig
2014-10-02 12:05 ` James Bottomley
2014-10-02 12:14 ` Hannes Reinecke
2014-10-02 13:06 ` James Bottomley
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=20141001211003.GA24820@infradead.org \
--to=hch@infradead.org \
--cc=hare@suse.de \
--cc=jbottomley@parallels.com \
--cc=linux-scsi@vger.kernel.org \
--cc=webbnh@hp.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 an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.