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Re: [Qemu-devel] What is the cause of -net socket, mcast bad performance
From: |
Stefan Hajnoczi |
Subject: |
Re: [Qemu-devel] What is the cause of -net socket, mcast bad performance? |
Date: |
Thu, 16 Aug 2012 11:19:36 +0100 |
On Thu, Aug 16, 2012 at 10:38 AM, Марк Коренберг <address@hidden> wrote:
> On my PC, tap <--> bridge <--> tap networking gives 600 megbit.
>
> Exactly the same, but -net socket,mcast gives about 1 megbit (!) I do not
> understand why.
>
> In my mind, -net socket,mcast is the same as tap, but ethernet frames are
> going in much simplier way: instead of
>
> qemu1 -> /dev/tun -> kernel/bridge -> /dev/tun -> qemu2
>
> in such way:
>
> qemu1 -> qemu2
>
>
> Does somebody knows, why -net socket,mcast works so slowly?
>
> People said, that VDE performace is like TAP. Why not to make same
> performace on -net socket,mcast ?
600 -> 1 Mbit/s performance difference is larger than expected.
Can you post more details?
1. qemu and Linux kernel versions
2. qemu command-lines for your tap and mcast setups
3. Which benchmark and the command-line to run the test
Stefan