From: Jan Kara <jack@ucw.cz>
To: Andreas Dilger <adilger@clusterfs.com>
Cc: David Chinner <dgc@sgi.com>,
linux-fsdevel@vger.kernel.org, linux-ext4@vger.kernel.org
Subject: Re: [RFC] Defragmentation interface
Date: Fri, 3 Nov 2006 20:38:00 +0100 [thread overview]
Message-ID: <20061103193800.GD17306@atrey.karlin.mff.cuni.cz> (raw)
In-Reply-To: <20061103192216.GA5252@schatzie.adilger.int>
> On Nov 03, 2006 15:30 +0100, Jan Kara wrote:
> > > - stripe unit and stripe width need to be exposed so defrag too
> > > can make correct placement decisions.
> > fs-specific thing...
>
> I think this is not just XFS-specific. It is very desirable to align
> large IO to the RAID stripe so that if you write stripe_width bytes
> you don't do 2 expensive read-modify-write steps, but rather a single
> write operation. Also RAID controllers have (large) internal cache
> "lines" and having aligned reads can help noticably, and also if array
> is doing RAID parity checking to avoid overhead of doing this for two
> stripes instead of one.
I see, thanks for information. On the other hand this is rather an
underlying block device feature than a fs thing, isn't it? So does it
make sence to pass this information via fs interface?
Honza
next prev parent reply other threads:[~2006-11-03 19:38 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-11-02 14:39 [RFC] Defragmentation interface Jan Kara
2006-11-02 22:59 ` David Chinner
2006-11-03 14:30 ` Jan Kara
2006-11-03 19:22 ` Andreas Dilger
2006-11-03 19:38 ` Jan Kara [this message]
2006-11-06 2:54 ` David Chinner
2006-11-06 17:44 ` Jan Kara
2006-11-07 3:03 ` David Chinner
2006-11-03 14:50 ` Dave Kleikamp
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=20061103193800.GD17306@atrey.karlin.mff.cuni.cz \
--to=jack@ucw.cz \
--cc=adilger@clusterfs.com \
--cc=dgc@sgi.com \
--cc=linux-ext4@vger.kernel.org \
--cc=linux-fsdevel@vger.kernel.org \
/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).