nfsd server cache flooded, try to increase nfsrc_floodlevel

[Harald Schmalzbauer]

 Bezüglich Rick Macklem's Nachricht vom 08.08.2013 14:20 (localtime):
> Lars Eggert wrote:
>> Hi,
>>
>> every few days or so, my -STABLE NFS server (v3 and v4) gets wedged
>> with a ton of messages about "nfsd server cache flooded, try to
>> increase nfsrc_floodlevel" in the log, and nfsstat shows TCPPeak at
>> 16385. It requires a reboot to unwedge, restarting the server does
>> not help.
>>
>> The clients are (mostly) six -CURRENT nfsv4 boxes that netboot from
>> the server and mount all drives from there.
>>
>> I googled around and saw that others have hit this issue, but I
>> haven't seen any resolution posted. I guess I can increase
>> NFSRVCACHE_FLOODLEVEL in the source, but I wonder if I wouldn't
>> simply hit the increase value after a little while longer...
>>
>> Lars
>>
> You can either try this patch (which dynamically adjusts nfsrc_floodlevel
> along with handling a variety of overhead issues for the DRC under heavy load):
>    http://people.freebsd.org/~rmacklem/drc4.patch
>
> or just bump it up a bunch. The default value was safe for a server with 256Mbytes
> of ram and a default mbuf cluster limit. The only thing you might have to do
> along with bumping NFSRC_FLOODLEVEL up is increasing kern.ipc.mbclusters.
>
> The variant of the above patch will make it into head someday, once I merge
> in changes from ivoras@'s similar patch and confer with him about it.

Dear all,

regarding the conversation from last year - quoted above,
I think I found the mentioned patch (it's variants) MFCd in r255532
(from http://svnweb.freebsd.org/base?view=revision&revision=254337),
so it's included in 9.3-RELEASE.

Unfortunately I'm still having the nfsrc_floodlevel problem with
OpenOwner=16385, CacheSize=16385 (in nfsstat -e -s) in my production
environment under 9.3-RELEASE-amd64.
Extremely light load on the server (2 (FreeBSD8/9) clients), but the
building client (nfsv4) locks up frequently. It mounts 'home' and
'ports/ports' via NFSv4 (this time, 'make index' in nfs-mounted
/usr/ports killed the nfsv4server).


    I found another interesting 3 years old patch/thread, which seems
never beeing comitted:
http://lists.freebsd.org/pipermail/freebsd-fs/2011-July/012016.html

I don't really understand all these details of nfs(v4), but I observe
problems with regular usage, so I wanted to ask if there are new
findings regarding the "nfsd server cache flooded, try to increase
nfsrc_floodlevel" messages (while 'nfsrc_floodlevel' doesn't seem to be
tunable in 9.3).
To my understanding, it's a problem on the server side, right?

Is the fix from 3 years back still adequate (does apply with view
offsets only to 9.3)?

I'm currently testing 9.3-RELEASE+noopen.patch, but it usually took two
or three days until the client locked up (hadn't looked for the reason
before the last issue, nfs(v4) was brand new reintroduced here)

Thanks,

-Harry

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