On Thursday 13 September 2007 23:03, David Chinner wrote:
quoted text
> On Thu, Sep 13, 2007 at 03:23:21AM +1000, Nick Piggin wrote:

quoted text
> > Well, it may not be easy to _fix_, but it's easy to try a few
> > improvements ;)
> >
> > How do I make an image and run a workload that will coerce XFS into
> > doing a significant number of vmaps?
>
> # mkfs.xfs -n size=16384 <dev>
>
> to create a filesystem with a 16k directory block size on a 4k page
> machine.
>
> Then just do operations on directories with lots of files in them
> (tens of thousands). Every directory operation will require at
> least one vmap in this situation - e.g. a traversal will result in
> lots and lots of blocks being read that will require vmap() for every
> directory block read from disk and an unmap almost immediately
> afterwards when the reference is dropped....

Ah, wow, thanks: I can reproduce it.
-
unsubscribe notice
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/