From: Alex Tomas <bzzz.tomas@gmail.com>
Subject: Re: delalloc fragmenting files?
Date: Fri, 02 Nov 2007 11:56:36 +0300
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Cc: Andreas Dilger <adilger@Sun.COM>,
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To: Eric Sandeen <sandeen@redhat.com>
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 (original mail from bzzz.tomas@gmail.com) for linux-ext4@vger.kernel.org; Fri,
 02 Nov 2007 08:56:54 +0000 (GMT)
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Eric,

would you mind to repeat the run and then grab /proc/fs/ext4/<dev>/mb_history?

thanks in advance, Alex

Eric Sandeen wrote:
> Eric Sandeen wrote:
>> 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...
> 
> Note, we're still getting out-of-order extents, too:
> 
> First block: 122880
> Last block: 2694143
> Discontinuity: Block 7424 is at 101376 (was 130303)
> Discontinuity: Block 28160 is at 133120 (was 122111)
> Discontinuity: Block 58368 is at 188416 (was 163327)
> Discontinuity: Block 66304 is at 180224 (was 196351)
> Discontinuity: Block 73984 is at 172032 (was 187903)
> Discontinuity: Block 81664 is at 167936 (was 179711)
> Discontinuity: Block 84736 is at 221184 (was 171007)
> Discontinuity: Block 92416 is at 212992 (was 228863)
> Discontinuity: Block 100096 is at 204800 (was 220671)
> Discontinuity: Block 107776 is at 198656 (was 212479)
> ...
> 
> I'm trying to find time to look into this but other things are knocking
> at my door so no promises...
> 
> -Eric
>