100Gb performance

hi,

i am running 14.2 on a DELL PowerEdge R750 with a mellanox/nvidia 100Gb nic  mlx5en: 

mce0: flags=1008843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST,LOWER_UP> metric 0 mtu 1500
 
	options=66ef07bb<RXCSUM,TXCSUM,VLAN_MTU,VLAN_HWTAGGING,JUMBO_MTU,VLAN_HWCSUM,TSO4,TSO6,LRO,VLAN_HWFILTER,NV,VLAN_HWTSO,LINKSTATE,RXCSUM_IPV6,TXCSUM_IPV6,HWSTATS,HWRXTSTMP,MEXTPG,VXLAN_HWCSUM,VXLAN_HWTSO>
       ether ...
       inet ... netmask 0xfffffc00 broadcast ….
       media: Ethernet 100GBase-KR4 <full-duplex,rxpause,txpause>
       status: active
       nd6 options=29<PERFORMNUD,IFDISABLED,AUTO_LINKLOCAL>

I’m doing a rsync from an iscsilon mounted via this mce0, the best max throughput is about 1GBs which is a bit depressing


but tcpdump -i mce0 says:
store-09# tcpdump -i mce0 host <same net as mce0>
tcpdump: verbose output suppressed, use -v[v]... for full protocol decode
listening on mce0, link-type EN10MB (Ethernet), snapshot length 262144 bytes
                                            **********

and shows no traffic!

any ideas?

thanks,
	danny