Re: [ kvm-Bugs-1884444 ] Virtual network (set up via TCP socket) dog slow, but vde ok

[Simon Gao <gao-g4dUTk+gKbW4mfPA/iJWtA@public.gmane.org>]

SourceForge.net wrote:
> Bugs item #1884444, was opened at 2008-02-01 15:30
> Message generated for change (Tracker Item Submitted) made by Item Submitter
> You can respond by visiting: 
> https://sourceforge.net/tracker/?func=detail&atid=893831&aid=1884444&group_id=180599
>
> Please note that this message will contain a full copy of the comment thread,
> including the initial issue submission, for this request,
> not just the latest update.
> Category: qemu
> Group: None
> Status: Open
> Resolution: None
> Priority: 5
> Private: No
> Submitted By: Alain Knaff (alain_knaff)
> Assigned to: Nobody/Anonymous (nobody)
> Summary: Virtual network (set up via TCP socket) dog slow, but vde ok
>
> Initial Comment:
> I've got two kvm virtual machines that I connect to gether via a virtual network:
>
> 1. A samba server (Kubuntu 7.10), whose network I set up with -net nic,vlan=1,macaddr=00:1B:FC:1C:00:01 -net socket,vlan=1,listen=127.0.0.1:1234
>
> 2. A Windows XP client, whose network I set up with -net nic,vlan=1,macaddr=00:1B:FC:1C:01:11 -net socket,vlan=1,connect=127.0.0.1:1234
>
> The Windows XP VM has joined the Samba VM's domain.
> When a domain user logs in, it takes litterally _minutes_ until its profile data is copied to the client, and same thing to copy it back to the server on logout.
>
> Setting up both with VDE, it's *much* quicker (only a couple of seconds, rather than minutes for login/logout).
>
> I also tried udp mcast networking, but couldn't get both VMs to communicate with each other. A tcpdump on the host shows traffic on port 1234. However, a tcpdump on the Kubuntu guest shows no traffic (not even arp) when I try to ping it from the windows VM
>
>
>   
I am also seeing this kind of problem. As a result, I can only run one
VM a time. If I run more than one VM, then both VM's network traffic
slows to a crawl (however, both VM can still connect to hosts on
different networks). It seems like that when more than one VM runs, all
VMs are put on a half-duplex switch, lots of collisions and packets drop
off, though they are not shown anywhere.

Simon

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