about netmap NETMAP_HW_RING with poll.

[root at 9du.org]

i have a test use pkt-gen.c 
# start pthread > 1 
netmap as receiver work on NETMAP_HW_RING  mode.

if i stop recv packet. system dmesg will show 
interrupt storm detected on "irq281:"; throttling interrupt source
interrupt storm detected on "irq281:"; throttling interrupt source
interrupt storm detected on "irq281:"; throttling interrupt source
interrupt storm detected on "irq281:"; throttling interrupt source
interrupt storm detected on "irq281:"; throttling interrupt source
......

i think this error may be with poll or 82599 device?

if i not use NETMAP_NW_RING will be ok!