Re: [Qemu-devel] [Fwd: qemu tx stop in cloonix]

[Stefan Hajnoczi]

On Sun, Feb 24, 2013 at 02:14:43PM -0600, address@hidden wrote:
> I use qemu inside a gplv3 software called cloonix, I have patched qemu to
> have unix sockets instead of inet ones but the bug I have with unix
> sockets may also happen with inet ones.
> 
> The bug can be reproduced in cloonix context by using iperf, it occurs
> randomly in a virtual cloonix network but occurs within seconds using
> iperf in nested virtualisation (cloonix inside cloonix), the problem
> begins when a lot of packets must be transmitted and the socket (inet in
> the classical qemu, unix in cloonix) gets full and
> qemu_net_queue_append_iov is called, then tx never restarts.
> 
> See under in the patch attached, the way I avoided queuing anything, it
> works, even if it is not a correction to the bug...
> 
> The patch is for version 21.3 of cloonix which uses qemu-1.4.0-rc1, but
> I now use qemu-1.4.0 and the bug is still there.

Thanks for the bug report.  This sounds like a problem with net/socket.c
- it's supposed to restart the queue when the socket becomes writable
again.

Can you share a way to reproduce this tx stall with vanilla QEMU?

Stefan