problems with network on em

[rolnas at gmail.com]

I'm experiencing network interface stalls on em in FreeBSD 8.1-RELEASE (-p1).
It looks like the problem could be solved in 8-STABLE, but should I upgrade to it ?
Is it OK to try to get only em driver code and recompile as module and try to run it ?

sysctl dev.em.2.stats=1:
...
em2: Missed Packets = 101334
em2: Receive No Buffers = 488
...
em2: RX overruns = 1356
em2: watchdog timeouts = 1
...

Only "ifconfig em2 down;ifconfig em2 up" helps for some time.
The same happens on em0 interface only, but not in the same time.
It is production (NAT) router with pf+pfsync+carp and failover over another router.
They are old "SunFire X4100" boxes (4GB RAM, 2*2 AMD Opteron 2.2GHz).

Regards, Rolandas Naujikas