Maintained by: NLnet Labs

[Unbound-users] Resource temporarily unavailable and query problem with unbound

Sebastian Nickel - Hetzner Online AG
Wed Nov 10 16:46:10 CET 2010


Hi,
I tried "netstat -su" and it showed me many UDP send buffer errors. So I
tried to set "net.core.wmem_max" to 8388608 (8m). It did not help. 

I googled a bit and found some network tuning guides for linux. I ended
up with the following sysctl.conf:

"""
net.core.rmem_max=8388608
net.core.wmem_max=8388608
net.core.rmem_default=262144
net.core.wmem_default=262144

net.ipv4.udp_mem=8388608 12582912 16777216
net.ipv4.udp_rmem_min=16384
net.ipv4.udp_wmem_min=16384
"""

This solved the problem and I do net get any of those log messages (and
unexpected timeouts) anymore.

One last question:
If I use "so-rcvbuf: 8m" in unbound.conf does this only set the
appropiate kernel variables (like I did with sysctl) or is the value
"8m" used in some calculations inside unbounds code, too?

Thank you for your help...

Best regards,
Sebastian

Am Dienstag, den 09.11.2010, 17:14 +0100 schrieb W.C.A. Wijngaards:
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> 
> Hi Sebastian,
> 
> On 11/09/2010 04:51 PM, Sebastian Nickel - Hetzner Online AG wrote:
> > Hello,
> > I tried to increase so-rcvbuf to 8m and to 16m. I changed
> > net.core.rmem_max values in system, too.
> > 
> > I still see many of those lines in the log:
> 
> Usually EAGAIN means the device is busy, but I have never seen it happen
> on send.  Attached a small patch, could you test this?  It sets
> SO_SNDBUF to the same value as SO_RCVBUF, perhaps the output buffer is full?
> 
> If it gives permission denied, change SO_SNDBUF into SO_SNDBUFFORCE
> 
> Otherwise, netstat -su?  does it report send buffer overruns (or can it
> possibly do so?).
> 
> Does a symmetric rcvbuf-sndbuf setting make sense (apart from this
> test)?  Or do you need to be able to configure the sndbuf?  (question
> only applicable if attachment solves problem :-)  ).
> 
> Best regards,
>    Wouter
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