zfs, a directory that used to hold lot of files and listing pause

[Peter]

Eugene M. Zheganin wrote:
> Hi.
>
> I have FreeBSD 10.2-STABLE r289293 (but I have observed this situation
> on different releases) and a zfs. I also have one directory that used to
> have a lot of (tens of thousands) files. I surely takes a lot of time to
> get a listing of it. But now I have 2 files and a couple of dozens
> directories in it (I sorted files into directories). Surprisingly,
> there's still a lag between "ls" and an output:

I see this on my pgsql_tmp dirs (where Postgres stores intermediate
query data that gets too big for mem - usually lots of files) - in
normal operation these dirs are completely empty, but make heavy disk
activity (even writing!) when doing ls.
Seems normal, I dont care as long as the thing is stable. One would need
to check how ZFS stores directories and what kind of fragmentation can
happen there. Or wait for some future feature that would do
housekeeping. ;)