Possible -HEAD problem with the Pi3 onboard ethernet

[Karl Denninger]

Under fairly heavy stress (~50% of the 100Mbps possible FDX performance)
I've now run into a problem that is turning into something I can repeat
without too much trouble by transmitting a large file through the device.

The system appears to "crash" from the outside.  It's not dead, however
-- it's got some sort of network buffer hang going on.  This is a Pi3
with current (-HEAD, FreeBSD 12.0-CURRENT #0 r318193M: Thu May 11
16:18:20 CDT 2017) software on it -- reverting to a mid-March kernel did
NOT change the behavior.

The symptomology is that the unit will start printing this on the console:

May 12 12:25:46 IPGw dhcpd: send_packet: No buffer space available
May 12 12:25:46 IPGw dhcpd: dhcp.c:3974: Failed to send 300 byte long
packet over ue0.3 interface.

ue0.3 is a VLAN for a private subnet and is not specific to the issue;
it also complains about no space on the primary too:

May 12 12:27:06 IPGw dhcpd: dhcp.c:3974: Failed to send 300 byte long
packet over ue0 interface.
May 12 12:27:13 IPGw dhcpd: send_packet: No buffer space available

netstat -m does /not /show any denied or delayed requests for network
buffers or mbuf exhaustion.  Systat -vm shows plenty of RAM available
(roughly half.)

An ifconfig ue0 down / ifconfig ue0 up sequence from the console clears
the hang.

Has anyone else seen anything similar to this?

-- 
Karl Denninger
karl at denninger.net <mailto:karl at denninger.net>
/The Market Ticker/
/[S/MIME encrypted email preferred]/
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