From: "Martin K. Petersen" <mkp@mkp.net>
To: Mike Christie <michaelc@cs.wisc.edu>
Cc: Guennadi Liakhovetski <g.liakhovetski@gmx.de>,
Kai Makisara <Kai.Makisara@kolumbus.fi>,
linux-scsi@vger.kernel.org
Subject: Re: use_clustering again
Date: Thu, 28 Sep 2006 17:36:56 -0400 [thread overview]
Message-ID: <yq1d59fk70n.fsf@sermon.lab.mkp.net> (raw)
In-Reply-To: <451C2795.8040509@cs.wisc.edu> (Mike Christie's message of "Thu, 28 Sep 2006 15:50:45 -0400")
>>>>> "Mike" == Mike Christie <michaelc@cs.wisc.edu> writes:
Mike> If you are just trying to get to 1MB, then instead of enabling
Mike> clustering we could also increase the defaul
Mike> SCSI_MAX_PHYS_SEGMENTS. It is 128 now, but there is a compile
Mike> option to set it it up to 256.
I have essentially been having the same problem doing big direct I/Os
using sg. I ended up bumping sg_tablesize to 1024 but only because I
knew the controllers used for this application support that many
scatter-gather segments.
As you mention, SG_ALL is 255 and that used to be the max value (quite
useless, just short of 1MB). In recent kernels it's been clamped to
128 thanks to getting intimate with the block/request layer.
These short lists are quite useless for contemporary tape hardware
that need a block size of 1MB at the minimum and preferably 2MB or
more...
--
Martin K. Petersen Oracle Linux Engineering
next prev parent reply other threads:[~2006-09-28 21:36 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <200609241605.32327.johna@onevista.com>
2006-09-27 21:32 ` SCSI tape block size Guennadi Liakhovetski
2006-09-28 14:34 ` Michael Reed
2006-09-28 19:47 ` Kai Makisara
2006-09-28 20:41 ` use_clustering again (was Re: SCSI tape block size) Guennadi Liakhovetski
2006-09-28 19:50 ` Mike Christie
2006-09-28 21:36 ` Martin K. Petersen [this message]
2006-09-30 20:52 ` SCSI tape block size Guennadi Liakhovetski
2006-10-01 10:42 ` Kai Makisara
2006-10-01 17:05 ` Guennadi Liakhovetski
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=yq1d59fk70n.fsf@sermon.lab.mkp.net \
--to=mkp@mkp.net \
--cc=Kai.Makisara@kolumbus.fi \
--cc=g.liakhovetski@gmx.de \
--cc=linux-scsi@vger.kernel.org \
--cc=michaelc@cs.wisc.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