From: Neil Brown <neilb@suse.de>
To: Greg Freemyer <greg.freemyer@gmail.com>
Cc: Matthew Wilcox <matthew@wil.cx>, Theodore Tso <tytso@mit.edu>,
Ric Wheeler <rwheeler@redhat.com>, "J?rn Engel" <joern@logfs.org>,
Matthew Wilcox <willy@linux.intel.com>,
Jens Axboe <jens.axboe@oracle.com>,
linux-fsdevel@vger.kernel.org, linux-ext4@vger.kernel.org,
Linux RAID <linux-raid@vger.kernel.org>
Subject: Re: Is TRIM/DISCARD going to be a performance problem?
Date: Tue, 12 May 2009 09:38:21 +1000 [thread overview]
Message-ID: <18952.46829.115084.46432@notabene.brown> (raw)
In-Reply-To: message from Greg Freemyer on Monday May 11
On Monday May 11, greg.freemyer@gmail.com wrote:
>
> And since the mdraid layer is not currently planning to track what has
> been discarded over time, when a re-shape comes along, it will
> effectively un-trim everything and rewrite 100% of the FS.
You might not call them "plans" exactly, but I have had thoughts
about tracking which part of an raid5 had 'live' data and which were
trimmed. I think that is the only way I could support TRIM, unless
devices guarantee that all trimmed blocks read a zeros, and that seems
unlikely.
You are right that the granularity would have to be at least
one stripe.
And a re-shape would be interesting, wouldn't it! We could probably
avoid instantiating every trimmed block, but in general quite a few
would get instantiated.. I hadn't thought about that...
NeilBrown
next prev parent reply other threads:[~2009-05-11 23:38 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-05-09 21:14 Is TRIM/DISCARD going to be a performance problem? Theodore Ts'o
2009-05-10 16:53 ` Jörn Engel
2009-05-11 8:37 ` Theodore Tso
2009-05-11 10:06 ` Jörn Engel
2009-05-11 10:18 ` Jens Axboe
2009-05-11 15:43 ` Jeff Garzik
2009-05-11 11:27 ` Theodore Tso
2009-05-11 12:09 ` Theodore Tso
2009-05-11 13:10 ` Greg Freemyer
2009-05-11 13:39 ` Matthew Wilcox
2009-05-11 14:27 ` Theodore Tso
2009-05-11 14:29 ` Ric Wheeler
2009-05-11 14:50 ` Theodore Tso
2009-05-11 14:58 ` Ric Wheeler
2009-05-11 15:00 ` Matthew Wilcox
2009-05-11 18:47 ` Greg Freemyer
2009-05-11 19:22 ` Andreas Dilger
2009-05-11 23:38 ` Neil Brown [this message]
2009-05-12 13:28 ` Greg Freemyer
2009-05-11 13:15 ` Ric Wheeler
2010-04-24 17:11 ` Phillip Susi
2009-05-11 12:43 ` Jörn Engel
2009-05-11 12:48 ` Matthew Wilcox
[not found] ` <f3177b9e0905111433i40e41c90r920d7ccf36442ffd@mail.gmail.com>
2009-05-11 22:03 ` Chris Worley
2009-05-11 16:30 ` Chris Worley
2009-05-11 8:12 ` Jens Axboe
2009-05-11 8:41 ` Theodore Tso
2009-05-11 8:49 ` Jens Axboe
2009-05-11 17:18 ` Chris Mason
2009-05-11 18:43 ` Matthew Wilcox
2009-05-11 18:53 ` Chris Mason
2009-05-11 19:19 ` Theodore Tso
2009-05-29 10:52 ` Florian Weimer
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=18952.46829.115084.46432@notabene.brown \
--to=neilb@suse.de \
--cc=greg.freemyer@gmail.com \
--cc=jens.axboe@oracle.com \
--cc=joern@logfs.org \
--cc=linux-ext4@vger.kernel.org \
--cc=linux-fsdevel@vger.kernel.org \
--cc=linux-raid@vger.kernel.org \
--cc=matthew@wil.cx \
--cc=rwheeler@redhat.com \
--cc=tytso@mit.edu \
--cc=willy@linux.intel.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).