Re: [CFT] delayed allocation and multipage I/O patches for 2.5.6.

[Mike Fedyk]

On Wed, Mar 13, 2002 at 11:50:32AM -0800, Andrew Morton wrote:
> Now, I think it's fair to say that the ext2/ext3 inter-file fragmentation
> issue is one of the three biggest performance problems in Linux.  (The
> other two being excessive latency in the page allocator due to VM writeback
> and read latency in the I/O scheduler).
> 
> The fix for interfile fragmentation lies inside ext2/ext3, not inside
> any generic layers of the kernel.    And this really is a must-fix,
> because the completion time for writeback is approximately proportional
> to the size of the filesystem.  So we're getting, what? Fifty percent
> slower per year?
> 
> The `tar xfz linux.tar.gz ; sync' workload can be sped up 4x-5x by
> using find_group_other() for directories.  I spent a week or so
> poking at this when it first came up.  Basically, *everything*
> which I did to address the rapid-growth problem ended up penalising
> the slow-growth fragmentation - long-term intra-file fragmentation
> suffered at the expense of short-term inter-file fragmentation.

I know ReiserFS has similar problems.

Can anyone say wheather JFS or XFS has this problem also?