From: Eric Sandeen <sandeen@redhat.com>
To: Phillip Susi <psusi@ubuntu.com>
Cc: Andreas Dilger <adilger@dilger.ca>, Fredrick <fjohnber@zoho.com>,
linux-ext4@vger.kernel.org
Subject: Re: ext4_fallocate
Date: Thu, 28 Jun 2012 11:23:14 -0400 [thread overview]
Message-ID: <4FEC76E2.1010006@redhat.com> (raw)
In-Reply-To: <4FEC744F.6010901@ubuntu.com>
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On 6/28/12 11:12 AM, Phillip Susi wrote:
> On 6/25/2012 3:33 AM, Andreas Dilger wrote:
>> There was a recent patch series "ext4: add an io-tree to track
>> block allocation" that may improve the performance for your case of
>> overwrite of uninitialized files, but it hasn't landed yet.
>
> I'm confused. Why is writing to uninitialized extents slow, and why
> would this help? If you have an uninitialized extent, then the blocks
> are already allocated, just flagged as containing uninitialized data.
> Writing to them should be no different than writing to initialized
> extents, save for the step of clearing the uninitialized flag.
The other piece is that large uninitialized extents get split into
up to 3 extents if you write into the middle of them so there are
potentially a lot more metadata updates flying around.
- -Eric
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next prev parent reply other threads:[~2012-06-28 15:23 UTC|newest]
Thread overview: 42+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-06-25 6:42 ext4_fallocate Fredrick
2012-06-25 7:33 ` ext4_fallocate Andreas Dilger
2012-06-28 15:12 ` ext4_fallocate Phillip Susi
2012-06-28 15:23 ` Eric Sandeen [this message]
2012-06-25 8:51 ` ext4_fallocate Zheng Liu
2012-06-25 19:04 ` ext4_fallocate Fredrick
2012-06-25 19:17 ` ext4_fallocate Theodore Ts'o
2012-06-26 1:23 ` ext4_fallocate Fredrick
2012-06-26 13:13 ` ext4_fallocate Ric Wheeler
2012-06-26 17:30 ` ext4_fallocate Theodore Ts'o
2012-06-26 18:06 ` ext4_fallocate Fredrick
2012-06-26 18:21 ` ext4_fallocate Ric Wheeler
2012-06-26 18:57 ` ext4_fallocate Ted Ts'o
2012-06-26 19:22 ` ext4_fallocate Ric Wheeler
2012-06-26 18:05 ` ext4_fallocate Fredrick
2012-06-26 18:59 ` ext4_fallocate Ted Ts'o
2012-06-26 19:30 ` ext4_fallocate Ric Wheeler
2012-06-26 19:57 ` ext4_fallocate Eric Sandeen
2012-06-26 20:44 ` ext4_fallocate Eric Sandeen
2012-06-27 15:14 ` ext4_fallocate Eric Sandeen
2012-06-27 19:30 ` ext4_fallocate Theodore Ts'o
2012-06-27 23:02 ` ext4_fallocate Eric Sandeen
2012-06-28 11:27 ` ext4_fallocate Ric Wheeler
2012-06-29 19:02 ` ext4_fallocate Andreas Dilger
2012-07-02 3:03 ` ext4_fallocate Zheng Liu
2012-06-28 12:48 ` ext4_fallocate Theodore Ts'o
2012-07-02 3:16 ` ext4_fallocate Zheng Liu
2012-07-02 16:33 ` ext4_fallocate Eric Sandeen
2012-07-02 17:44 ` ext4_fallocate Jan Kara
2012-07-02 17:48 ` ext4_fallocate Ric Wheeler
2012-07-03 17:41 ` ext4_fallocate Zheng Liu
2012-07-03 17:57 ` ext4_fallocate Zach Brown
2012-07-04 2:23 ` ext4_fallocate Zheng Liu
2012-07-02 18:01 ` ext4_fallocate Theodore Ts'o
2012-07-03 9:30 ` ext4_fallocate Jan Kara
2012-07-04 1:15 ` ext4_fallocate Phillip Susi
2012-07-04 2:36 ` ext4_fallocate Zheng Liu
2012-07-04 3:06 ` ext4_fallocate Phillip Susi
2012-07-04 3:48 ` ext4_fallocate Zheng Liu
2012-07-04 12:20 ` ext4_fallocate Ric Wheeler
2012-07-04 13:25 ` ext4_fallocate Zheng Liu
2012-06-26 13:06 ` ext4_fallocate Eric Sandeen
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