From: Eric Sandeen <sandeen@redhat.com>
To: Alex Tomas <bzzz.tomas@gmail.com>
Cc: Andreas Dilger <adilger@Sun.COM>,
ext4 development <linux-ext4@vger.kernel.org>
Subject: Re: delalloc fragmenting files?
Date: Thu, 01 Nov 2007 10:20:18 -0500 [thread overview]
Message-ID: <4729EEB2.9090406@redhat.com> (raw)
In-Reply-To: <47291F62.3000008@gmail.com>
Alex Tomas wrote:
> please, try the patch attached.
Looks quite a bit better:
http://people.redhat.com/esandeen/seekwatcher/ext4-alex.png
http://people.redhat.com/esandeen/seekwatcher/ext4-alex-ext4-dd-write.png
http://people.redhat.com/esandeen/seekwatcher/ext4-alex-ext4-xfs-dd-write.png
It is much less fragmented, although still not exactly the nice linear
allocation I'd expect from a single threaded large write on a fresh fs...
-Eric
> thanks, Alex
>
> Eric Sandeen wrote:
>> One thing that seems to be happening is that thanks to delalloc, a nice
>> big request is coming in (only 1036 blocks of the 4096, not quite sure
>> why), but then it gets into ext4_mb_normalize_request(), which finds the
>> most blocks it can "preallocate" is 256, and chops down the request to
>> 256 blocks. Shouldn't this preallocation be over & above what was asked
>> for, vs. reducing the request?
>>
>> Ok, so, we get allocations in 256-block chunks... Why they don't all
>> come out contiguous, I don't know yet...
>>
>> -Eric
>
next prev parent reply other threads:[~2007-11-01 15:20 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-10-26 21:24 delalloc fragmenting files? Eric Sandeen
2007-10-26 22:19 ` Andreas Dilger
2007-10-27 2:54 ` Eric Sandeen
2007-10-27 3:08 ` Eric Sandeen
2007-10-31 21:01 ` Eric Sandeen
2007-11-01 0:35 ` Alex Tomas
2007-11-01 15:20 ` Eric Sandeen [this message]
2007-11-01 19:05 ` Eric Sandeen
2007-11-02 8:56 ` Alex Tomas
2007-11-02 15:41 ` Eric Sandeen
2007-11-04 18:36 ` Alex Tomas
2007-11-05 17:37 ` Eric Sandeen
2007-11-05 17:39 ` Eric Sandeen
2007-11-05 17:45 ` Alex Tomas
2007-11-05 18:51 ` Andreas Dilger
2007-11-05 18:54 ` Eric Sandeen
2007-11-06 19:54 ` Eric Sandeen
2007-11-07 20:37 ` Andreas Dilger
2007-11-07 20:53 ` Eric Sandeen
2007-10-29 19:13 ` Eric Sandeen
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=4729EEB2.9090406@redhat.com \
--to=sandeen@redhat.com \
--cc=adilger@Sun.COM \
--cc=bzzz.tomas@gmail.com \
--cc=linux-ext4@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).