Slow NFSv4 performance, was: Re: ZFSv28+NFSv4 poor file creation performance, "sync=disabled" has no effect

[David Brodbeck]

On Mon, Sep 5, 2011 at 2:16 AM, Pawel Jakub Dawidek <pjd at freebsd.org> wrote:

> It would be good if you could try your test on FreeBSD directly. This
> way we could see if ZFS is to blame or NFS.
>

Okay, it appears it is in fact an NFSv4 problem, and I've been barking up
the wrong tree.  I shared out an NFSv4 mountpoint with a UFS ramdisk as the
backing store, and I got the same slow results.  I was fooled by the fact
that the numbers were similar to what I got using OpenSolaris with the ZIL
enabled.  (This is what I get for making assumptions.)

Interestingly enough, if I use NFSv3 instead of NFSv4, performance increases
dramatically.

It appears it's FreeBSD's NFSv4 server, or the way it's interacting with
Linux's client, that's the culprit here.  I'm not sure if there are knobs I
should be tweaking to make it perform better; any suggestions on what to try
next?

-- 
David Brodbeck
System Administrator, Linguistics
University of Washington