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List:       linux-kernel
Subject:    Re: ext4 is faster with LVM than without, and other filesystem benchmarks
From:       Eric Sandeen <sandeen () sandeen ! net>
Date:       2010-05-07 17:49:00
Message-ID: 4BE4528C.5000305 () sandeen ! net
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Bernd Eckenfels wrote:
> In article <20100507142310.GF13143@lh.kyla.fi> you wrote:
>> I think the most surprising result of the benchmarks is that ext4
>> seems to be significantly faster under LVM than on the raw /dev/sdd1
>> partition. Without LVM the variance in run times is much larger.
> 
> Sounds like the syncs/barriers never reach the disk with LVM. What mount
> journal/sync options did you use?  default?  Is dmesg telling you that
> barriers have been turned off for the lvm case?  IF yo uwant it fast and
> dirty try nobarrier,data=writeback :)

LVM barriers should be working in that kernel, though... still, comparing
mount -o nobarrier on each might yield a clue there.

-Eric

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