On Thu, Dec 15, 2011 at 04:48:13PM -0000, Vincent Autefage wrote: > Here is the problem ! > > The Ubuntu version works only because it not uses an *Intel e1000* but a > *rtl8139*. > Therefore, the problem about the e1000 is present in *all* version > (original or ubuntu ones). > > Thus, the file *e1000.c* must contain some instructions which imply the > bad TC behavior.
You are right! Looking back at your QEMU command-line you are not explicitly specifying the NIC model so the default will take effect. Now we're back to square one: e1000.c performs poorly when the tc command you posted is used. We don't know why yet. Michael: Have you ever encountered unexpectedly low throughput when tc is used inside the guest? # tc qdisc add dev eth0 root tbf rate 20mbit burst 20k latency 50ms The observed throughput from iperf is only 100kbit/s, not around 20mbit/s as expected. When tc is not run inside the guest then the NIC saturates 20mbit/s easily. Stefan
