On Mon, 5 Nov 2001, Alexander Viro wrote:
>
> Oh, come on. (a) is obvious, but obviously not enough ;-)
I agree, but I think it's a fairly good starting point to build up some
heuristics.
Also note that traditonal UNIX implementations will have a hard time doing
anything more fine-grained than "is the parent the root directory or not".
Information about grandparents etc has been lost long before we get to
"ialloc()", so I bet you'll find experimental data only on that one-level
thing.
But it is probably not a binary decision in real life.
In real life, you're ok switching cylinder groups for /home vs /usr, but
you're also ok switching groups for /home/torvalds vs /home/viro. And it's
still reasonably likely that it makes sense to switch groups in
/home/torvalds between 'src' and 'public_html'.
But the deeper down in the directory hierarchy you get, the less likely it
is that it makes sense.
And yes, it's just a heuristic. But it's one that where thanks to the
dcache we could reasonably easily do more than just a black-and-white
"root vs non-root" thing.
> Yes, but block reservation also makes sense (otherwise we can end up
> putting a directory into parent's CG only to have all children
> going there _and_ getting far from their data). Which might be the
> problem with original code, BTW.
Yes, agreed. Disk space allocations should definitely be part of the
heuristics, and that's obviously both inode and blocks.
I do believe that there are probably more "high-level" heuristics that can
be useful, though. Looking at man common big trees, the ownership issue is
one obvious clue. Sadly the trees obviously end up being _created_ without
owner information, and the chown/chgrp happens later, but it might still
be useable for some clues.
Linus
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
This archive was generated by hypermail 2b29 : Wed Nov 07 2001 - 21:00:28 EST