On 11/25/11 14:19, Kris Bauer wrote:
On Thu, Nov 24, 2011 at 8:00 PM, Jeremy Chadwick
<[email protected]>wrote:
On Thu, Nov 24, 2011 at 07:13:39PM -0600, Kris Bauer wrote:
On Thu, Nov 24, 2011 at 5:35 PM, Adrian Chadd<[email protected]>
wrote:
Have you tried disabling the tcp offload features of your NIC?
Adrian
To test this, I added net.inet.tcp.tso=0 to sysctl.conf and restarted the
box; it didn't work. net.inet.tcp.reass.cursegments immediately started
climbing up and were exhausted within an hour.
I think Adrian was referring to RXCSUM and TXCSUM on your NIC; TSO is
another offloading feature.
See ifconfig(8) for how to disable those.
Be aware that disabling them in real-time (e.g. ifconfig xxx -rxcsum
-txcsum) may cause problems; there are some NIC drivers on FreeBSD which
do not like you doing this once the NIC has established link (meaning
"reloading the driver" (for lack of better term) results in wonky
behaviour). So you may instead want to add those hyphen-options to your
ifconfig_XXX lines in /etc/rc.conf and reboot the box.
If none of this solves the problem, then I consider this a priority 0
blocker (read: "all hands on deck") issue with the IP stack in FreeBSD
9.x and will need immediate attention.
I would strongly recommend a developer or clueful end-user begin
tracking down who committed all of these bits and CC them into the
thread. I would start by looking who implemented the
net.inet.tcp.reass.cursegments sysctl, because that isn't in RELENG_8 at
all.
I have added -rxcsum -txcsum -tso to rc.conf and rebooted the box. This
has not solved the problem. After a half-hour usage, I'm already up to
reass.cursegments=2182 and it keeps climbing.
This is pretty much guaranteed to be an accounting problem in the TCP
reassembly code (netinet/tcp_reass.c), not a driver related issue. I
would not expect any amount of tweaking, tuning or driver option
twiddling to change the outcome (but if you do find something which
alleviates it, do let us know).
Kris, are you in a position to test kernel patches on the machine which
is experiencing this problem?
Cheers,
Lawrence
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