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From: | Anthony Liguori |
Subject: | [Qemu-devel] Re: [PATCH 0/8] vlan cleanup |
Date: | Tue, 13 Jul 2010 14:22:47 -0500 |
User-agent: | Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.1.10) Gecko/20100528 Lightning/1.0b1 Thunderbird/3.0.5 |
On 07/13/2010 02:08 PM, Jan Kiszka wrote:
Anthony Liguori wrote:On 07/13/2010 07:48 AM, Jan Kiszka wrote:Miguel Di Ciurcio Filho wrote:On Tue, Jul 13, 2010 at 3:16 AM, Jan Kiszka<address@hidden> wrote:Miguel Di Ciurcio Filho wrote:This series removes the vlan stuff without mercy. I've tried to make the steps as small as possible, but the last one is huge. I did some basic tests and networking is still working, so reviews are welcome :-DSorry, this is a bit too rude. This not only removes the vlan model, something one may talk about, but also the innocent socket back-ends and the useful pcap dump support. Socket back-ends allow quick and easy unprivileged inter-VM network setups. Nothing for production systems, but useful for testing purposes on boxes where taps are not allowed or unhandy to configure.I agree that it might be handy sometimes, but one could use VDE for that too. Runs on user-space and can be tunneled over SSH or netcat [1].Yes, I know. But it requires yet another process as hop. In contrast, peer-to-peer sockets used to be as fast as taps in certain setup (now taps became faster again).Dump is critical to maintain. sockets is not terribly useful without vlan. Honestly, I have a hard time agreeing that it's terribly useful to begin with. I don't buy an argument about "ease-of-use" because how to properly configure the sockets backend is not at all obvious.Old style: -net socket,listen=:12345 plus -net socket,connect=127.0.0.1:12345 and you have linked two VMs. New style would be less handy (unless we map -net on -netdev once vlans are gone), but still following the same pattern.
For peer-to-peer. But -net socket + vlan also supports multiple point.And in this example, you're forwarding TCP over TCP which is pretty awful from a perf perspective. Last time I did a quick sniff test with -net socket, it was amazingly slow (like 10s of KB/s).
I bet there is only a minor bit missing to get "-netdev socket" working, given that slirp apparently works. If I had time, I would look into this.
I'm sure you could, but the result is a tremendously crippled version of -net socket which leads me to wonder if it's still even worth supporting.
Regards, Anthony Liguori
Jan
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