Weird NFS client lock up with Mellanox cards :/

[Hans Petter Selasky]

On 07/19/16 15:28, Justin Clift wrote:
> Hi all,
>
> Brian Krusic (CC'd), has been kind enough to put time into some
> performance testing of Mellanox ConnectX-3 Pro cards in 40GbE mode,
> with FreeNAS 9.10-STABLE.  (That uses FreeBSD 10-STABLE as it's
> base OS)
>
> Weirdly, his NFS clients are locking up when using Mellanox cards,
> but not with SolarFlare ones.
>
>   https://bugs.freenas.org/issues/7659#note-40
>
> Comparing the OFED code in FreeNAS 9.10-STABLE to FreeNSD 10-STABLE,
> there's one patch difference.  It's a recent one from 3 days ago:
>
>   MFC r301877
>   Add a missing error check for a malloc() call in idr_get().
>   https://github.com/freebsd/freebsd/commit/03f3328da077d2def40be7dea8d13c74c2ccd447
>
> Does anyone know if this missing patch could result in a slow down
> of NFS clients (but not Samba/SMB)?  Maybe memory leak style, leading
> to a lack of resources or something?
>
> Hoping it's really this simple.  But if not... does anyone have
> suggestions on what to try for figuring this out?
>
> Regards and best wishes,
>

Hi,

Might be some timing issue not related to the Mellanox cards. What link 
speeds is being used?

What happens when the lockup happens?

Is RSS being used?

--HPS