andre at freebsd.org
Sun Aug 29 19:10:44 UTC 2010
On 29.08.2010 19:16, Mike Tancsa wrote:
> At 11:33 AM 8/29/2010, Andre Oppermann wrote:
>> On 29.08.2010 16:09, Mike Tancsa wrote:
>>> After upgrading to a recent STABLE, I have been seeing the following sporadic errors
>>> Aug 28 04:15:15 smarthost2 kernel: TCP: [xx.yy.165.120]:53617 to [xx.yy.164.50]:25; syncache_socket:
>>> Socket create failed due to limits or memory shortage
>>> this is with
>>> FreeBSD 8.1-STABLE #7: Wed Aug 25 15:32:05 EDT 2010
>>> and the previous kernel was from July 20th.
>>> The odd thing is that the error is triggered from a RELENG_6 host only it would seem. I noticed
>>> there are a number of syncache and tcp updates to RELENG_8, is it possible this is related ? I dont
>>> have any specific tweaks in /etc/sysctl.conf
>>> other than
>>> net.inet.tcp.log_in_vain: 1
>>> net.inet.udp.log_in_vain: 1
>> The log_in_vain sysctl would cause the logging of syncache errors
>> as well (net.inet.tcp.log_debug). This was a POLA violation and
>> I've separated them on August 27 on 8-stable. So if you update
>> you won't see them anymore. That doesn't change the fact that
>> the socket create failed though.
>> If it only happens from a RELENG_6 box it probably is a problem
>> with port re-usage by RELENG_6. The difficulty is that sonewconn()
>> fails and doesn't return an error code. Hence it may be one of
>> listen queue limits reached, memory shortage or a problem with
>> inserting the inpcb into the hash lists.
> Actually, I think I might have found the issue. I was focusing on the "memory" part not the limits.
> The 'RELENG_6 only' is just a fluke as thats a box that sends a lot of email to this particular
> server. It turns out, sendmail was rate limiting the server
> sm-mta: deferring connections on daemon IPv4: 8 per second
> and somehow syncache is aware/logs this now where as it did not before ?
When sendmail is deferring the connections it should not show up
in the syncache logs. The accept() by sendmail is much later than
when the socket for a new connection is created in syncache. Here
it points to the limits in the listen queue. Maybe sendmail is
getting behind in accepting new connections and the listen queue
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