Performance problem using Intel X520-DA2

[Marcin Markowski]

  Hello,

This message has been sent to freebsd-performance@ but got
the information that should contact also with freebsd-net at .

We use FreeBSD as sniffer (libpcap programs) and we experience
performance problems when incoming traffic is greater than 7.5Gbps/s.
If we check 'top' we see that first irq from network card is using
100% CPU. I've tested this on FreeBSD 8.2-RELEASE and 9.0-RELEASE
(on 9.0 we can see also kernel thread named {ix0 que} using 100% CPU),
and both systems behave the same. In logs we see also:
interrupt storm detected on "irq268:"; throttling interrupt source

Our server platform is Intel SR2600URBRP, 2x Xeon X5650, 6GB RAM and
NIC Intel X520-DA2.

I'm not sure if problem is with NIC or motherboard in SR2600URBRP,
because everything is fine when we use other server configuration:
Intel SR1630GP, 1x Xeon X3450, 8GB RAM, NIC X520-DA2

My /boot/loader.conf:
kern.ipc.nmbclusters=262144
hw.ixgbe.rxd=2048
hw.ixgbe.txd=2048
hw.ixgbe.num_queues=16

/etc/sysctl.conf
hw.intr_storm_threshold=10000

-- 
Marcin Markowski