Re: 2.6.36 io bring the system to its knees

[Christoph Hellwig]

On Wed, Nov 10, 2010 at 09:33:29AM -0500, Theodore Tso wrote:
> The chance that this occurs using data=writeback in ext4 is much less, BTW, because with delayed allocation we delay updating the inode until right before we write the block.  I have a plan for changing things so that we write the data blocks *first* and then update the metadata blocks second, which will mean that ext4 data=ordered will go away entirely, and we'll get both the safety and as well as avoiding the forced data page writeouts during journal commits.

That's the scheme used by XFS and btrfs in one form or another.  Chris
also had a patch to implement it for ext3, which unfortunately fell
under the floor.

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