Re: 2.6.36 io bring the system to its knees

[Chris Mason]

Excerpts from Christoph Hellwig's message of 2010-11-10 09:57:12 -0500:
> 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.

It probably still applies, but by the time I had it stable I realized
that ext4 was really a better place to fix this stuff.  ext3 is what it
is (good and bad), and a big change like my data=guarded code probably
isn't the best way to help.

-chris
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