Description of problem:
When I run multiple netperf clients on host, they connect with the
netperf-server in guest.
clients fail to execute cmds and output "interrupted system call"

Version-Release number of selected component (if applicable):
qemu-kvm-0.12.1.2-2.171.el6.x86_64
kernel 2.6.32-167.el6.x86_64

How reproducible:
always

Steps to Reproduce:
1. boot up a guest with multiple nics (rtl8139)
2. setup and launch netperf server in guest
guest)# ./netserver
3. setup and launch multiple netperf client in host.
host)# while true;do ./netperf -t TCP_STREAM -H $guest_ip ;echo Tcp:$?;done &
host)# while true;do ./netperf -t UDP_STREAM -H $guest_ip;echo Udp:$?;done &
host)# while true;do ./netperf -H $guest_ip -- -m 200; echo $? Other:$?;done &

Actual results:
netperf clients outputted:
interrupted system call 
netperf remote error 4

Expected results:
netperf commands completed. 

Additional info:
In step 1, I start guest with 4 nics.
In step 3, launch 4 netperf client in host.  one netperf client per guest nic.

This problem also exists on RHEl6.1.z
qemu-kvm-0.12.1.2-2.160.el6_1.3.x86_64
kernel 2.6.32-131.6.1.el6.x86_64