full socket buffers

[Mirek Lauš]

On Wed, Feb 9, 2011 at 4:56 PM, Mirek Lauš <mirek at admino.cz> wrote:
> On Wed, Feb 9, 2011 at 3:42 PM, Glenn Satchell
> <glenn.satchell at uniq.com.au> wrote:
>> On 02/10/11 00:40, Mirek Lauš wrote:
>>>
>>> On Wed, Feb 9, 2011 at 2:38 PM, David Forrest<drf at maplepark.com>  wrote:
>>>>
>>>> On Wed, 9 Feb 2011, Mirek Lauš wrote:
>>>>
>>>>> According to this:
>>>>> http://www.29west.com/docs/THPM/udp-buffer-sizing.html
>>>>> the kern.ipc.maxsockbuf is the right oid. The problem only occurs after
>>>>> few days
>>>>> of dhcpd process running then it begins do drop UDP randomly forcing us
>>>>> to
>>>>> restart dhcpd process. Then everything goes well for few days again. Now
>>>>> I really don't know where to look for help.
>>>>>
>>>>> Regards,
>>>>> Miroslav
>>>>
>>>> Perhaps a cron job restarting dhcpd during an inactive time period every
>>>> couple days would stop the problem from affecting your users.
>>>
>>> Yes. But I don't like this solution because it is not a solution. It
>>> is a workaround.
>>> We would not be able to find the real cause of the issue.
>>>
>>> Regards,Miroslav
>>
>> Is there any pattern, such as time of day when it occurs? Any other heavy
>> network traffic at the time? Perhaps this is a symptom of some other issue?
>> Have you confirmed with netstat -s that the number of packets dropped due to
>> full socket buffers increases when the problem is apparent?
>>
>> How about increasing the buffer size a bit further? 256k is pretty small by
>> today's standards. In an earlier post you mentioned you tried 1MB, so
>> perhaps try 2MB, then 4, maybe 8MB to see if that is sufficient.
>>
>> The web page you refer to seems to explain the settings quite well.
>
> No. It is completely random. When the issue occur, the netstat -s -p
> udp show continual
> loss of UDP packets due to full socket buffers.
>
> I already stated that the kern.ipc.maxsockbuf is set to 8MB and
> net.inet.udp.recvspace is set to 1MB. How can I monitor buffer usage?

And no, there is no heavy network traffic at the time.

-ml