Re: [00/17] Large Blocksize Support V3

From: Theodore Tso
Date: Fri Apr 27 2007 - 12:46:00 EST

On Fri, Apr 27, 2007 at 01:48:49AM -0700, Andrew Morton wrote:
> And other filesystems (ie: ext4) _might_ use it. But ext4 is extent-based,
> so perhaps it's not work churning the on-disk format to get a bit of a
> boost in the block allocator.

Well, ext3 could definitely use it; there are people using 8k and 16k
blocksizes on ia64 systems today. Those filesystems can't be mounted
on x86 or x86_64 systems because our pagesize is 4k, though.

And I imagine that ext4 might want to use a large blocksize too ---
after all, XFS is extent based as well, and not _all_ of the
advantages of using a larger blocksize are related to brain-damaged
storage subsystems with short SG list support. Whether the advantages
offset the internal fragmentation overhead or the complexity of adding
fragments support is a different question, of course.

So while the jury is out about how many other filesystems might use
it, I suspect it's more than you might think. At the very least,
there may be some IA64 users who might be trying to transition their
way to x86_64, and have existing filesystems using a 8k or 16k
block filesystems. :-)

- Ted
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