SR-IOV dropping packets when *other* VFs are configured

Hi,

I've been doing some testing using an HP Ethernet 1Gb 2p 361T Adapter in a DL380p Gen8.  The software used is CentOS 6.4 and igb 4.3.0 and igbvf 2.3.2 Intel drivers.  I've noticed that when a VF NIC is under load (typically reading multicast at 80-110 MB/s), the packets can get dropped when one or more of the following are performed against different VFs on the same card:

• ethtool -G
• vconfig
• ip link set up dev eth1.NNN
• python sock.setsockopt(socket.IPPROTO_IP, socket.IP_ADD_MEMBERSHIP,mreq) call

Is this to be expected?

Thanks in advance,

        == k+ ==