[Qemu-devel] A problem about network throughput

[Jiang Wang]

Hi:

I am working on a project using QEMU to emulate a special device which
sends out the data automatically without a driver. I modified the
rtl8139 NIC and it works OK with low speed (<=16KB/s) . However, if
the throughput becomes 32KB/s or above, the guest OS will hang (no
response).  If I use the original rtl8139.c, the throughput is around
1MB/s. So I expect that my modified version should have the similar
throughput.  The guest OS is CentOS 5.3 and the host is CentOS5.3
64bit.

I use qemu_mod_timer to send out the data periodically. In the timer
function, it calls rtl8139_transmit() multiple times to send out data.
The timer interval is 1 sec. I have tried to increase the size of one
packet but it does not work. I suspect that the timer function may
take too long to finish and cause the problem but I am not sure.

Any suggestions?

Regards,

Jiang