Re: Enabling h-trees too early?

[Andi Kleen <andi@firstfloor.org>]

Theodore Tso <tytso@mit.edu> writes:
> 
> Certainly one of the things that we could consider is for small
> directories to do an in-memory sort of all of the directory entries at
> opendir() time, and keeping that list until it is closed.  We can't do
> this for really big directories, but we could easily do it for
> directories under 32k or 64k.

I assume you mean sort by inode, because sort by htree key would
be as bad as htrees.

But wouldn't that break parallel readdir for a directory that just grows
from <32/64K to over it?  e.g. if the sort moves already read 
entries to after the  cursor readdir would return some entries twice.

I suspect you would need to keep it always sorted after that no matter
how big it gets. So the 32/64k boundary seems useless and you would
need a sorted potentially partial in memory rbtree anyways.

-Andi