Hi,

I did some benchmarking on the existing L2 network namespaces.

These patches are included in the lxc patchset at:
    http://lxc.sourceforge.net/patches/2.6.20
The lxc7 patchset series contains Dmitry's patchset
The lxc8 patchset series contains Eric's patchset

Here are the following scenarii I made in order to do some simple
benchmarking on the network namespace. I tested three kernels:

     * Vanilla kernel 2.6.20

     * lxc7 with Dmitry's patchset based on 2.6.20
       * L3 network namespace has been removed to do testing

     * lxc8 with Eric's patchset based on 2.6.20

I didn't do any tests on Linux-Vserver because it is L3 namespace and
it is not comparable with the L2 namespace implementation. If anyone
is interessted by Linux-Vserver performances, that can be found at
http://lxc.sf.net. Roughly, we know there is no performance
degradation.

For each kernel, several configurations were tested:

 * vanilla, obviously, only one configuration was tested for reference
   values.

 * lxc7, network namespace
  - compiled out
  - compiled in
    - without container
    - inside a container with ip_forward, route and veth
    - inside a container with a bridge and veth

 * lxc8, network namespace
  - compiled out
  - compiled in
    - without container
    - inside a container with a real network device (eth1 was moved
      in the container instead of using an etun device)
    - inside a container with ip_forward, route and etun
    - inside a container with a bridge and etun

Each benchmarking has been done with 2 machines running netperf and
tbench. A dedicated machine with a RH4 kernel run the bench servers.

For each bench, netperf and tbench, the tests are ran on:

 * Intel Xeon EM64T, Bi-processor 2,8GHz with hyperthreading
activated, 4GB of RAM and Gigabyte NIC (tg3)

 * AMD Athlon MP 1800+, Bi-processor 1,5GHz, 1GB of RAM and Gigabyte
   NIC (dl2000)

Each tests are run on these machines in order to have a CPU relative 
overhead.


# bench on vanilla
===================


 ----------- --------------------------------------
| Netperf   | CPU usage (%) | Throughput (Mbits/s) |
 ----------- --------------------------------------
| on xeon   |      5.99     |        941.38        |
 --------------------------------------------------
| on athlon |     28.17     |        844.82        |
 --------------------------------------------------

 ----------- -----------------------
| Tbench    | Throughput (MBytes/s) |
 ----------- -----------------------
| on xeon   |         66.35         |
 -----------------------------------
| on athlon |         65.31         |
 -----------------------------------


# bench from Dmitry's patchset
==============================


1 - with net_ns compiled out
----------------------------

 ----------- -----------------------------------------------------------
| Netperf   | CPU usage (%) / overhead | Throughput (Mbits/s) / changed |
 ----------- -----------------------------------------------------------
| on xeon   |      5.93 / -1 %         |        941.32  / 0 %           |
 -----------------------------------------------------------------------
| on athlon |     28.89 / +2.5 %       |        842.78 / -0.2 %         |
 -----------------------------------------------------------------------

 ----------- ---------------------------------
| Tbench    | Throughput (MBytes/s) / changed |
 ----------- ---------------------------------
| on xeon   |         67.00 / +0.9 %          |
 ---------------------------------------------
| on athlon |         65.45 / 0 %             |
 ---------------------------------------------

  Observation : no noticeable overhead


2 - with net_ns compiled in
---------------------------


    2.1 - without container
    -----------------------

 ----------- -----------------------------------------------------------
| Netperf   | CPU usage (%) / overhead | Throughput (Mbits/s) / changed |
 ----------- -----------------------------------------------------------
| on xeon   |      6.23 / +4 %         |        941.35  / 0 %           |
 -----------------------------------------------------------------------
| on athlon |     28.83 / +2.3 %       |        850.76 / +0.7 %         |
 -----------------------------------------------------------------------

 ----------- ---------------------------------
| Tbench    | Throughput (MBytes/s) / changed |
 ----------- ---------------------------------
| on xeon   |         67.00 / 0 %             |
 ---------------------------------------------
| on athlon |         65.45 / 0 %             |
 ---------------------------------------------

  Observation : no noticeable overhead


    2.2 - inside the container with veth and routes
    -----------------------------------------------

 ----------- -----------------------------------------------------------
| Netperf   | CPU usage (%) / overhead | Throughput (Mbits/s) / changed |
 ----------- -----------------------------------------------------------
| on xeon   |      17.14 / +186.1 %      |        941.34  / 0 %         |
 -----------------------------------------------------------------------
| on athlon |      49.99 / +77.45 %      |        838.85 / +0.7 %       |
 -----------------------------------------------------------------------

 ----------- ---------------------------------
| Tbench    | Throughput (MBytes/s) / changed |
 ----------- ---------------------------------
| on xeon   |         66.00 / -0.5 %          |
 ---------------------------------------------
| on athlon |         61.00 / -6.65 %         |
 ---------------------------------------------

  Observation : CPU overhead is very big, throughput is impacted on
  the less powerful machine


    2.3 - inside the container with veth and bridge
    -----------------------------------------------

 ----------- -----------------------------------------------------------
| Netperf   | CPU usage (%) / overhead | Throughput (Mbits/s) / changed |
 ----------- -----------------------------------------------------------
| on xeon   |      19.14 / +299 %      |        941.18  / 0 %           |
 -----------------------------------------------------------------------
| on athlon |      49.98 / +77.42 %    |        831.65 / -1.5 %         |
 -----------------------------------------------------------------------

 ----------- ---------------------------------
| Tbench    | Throughput (MBytes/s) / changed |
 ----------- ---------------------------------
| on xeon   |         64.00 / -3.5 %          |
 ---------------------------------------------
| on athlon |         60.07 / -8.3 %          |
 ---------------------------------------------

  Observation : CPU overhead is very big, throughput is impacted on
  the less powerful machine


# bench from Eric's patchset
============================


1 - with net_ns compiled out
----------------------------

 ----------- -----------------------------------------------------------
| Netperf   | CPU usage (%) / overhead | Throughput (Mbits/s) / changed |
 ----------- -----------------------------------------------------------
| on xeon   |      6.04 / +0.8 %       |        941.33  / 0 %           |
 -----------------------------------------------------------------------
| on athlon |      28.45 / +1 %        |        840.76 /  -0.5 %        |
 -----------------------------------------------------------------------

 ----------- ---------------------------------
| Tbench    | Throughput (MBytes/s) / changed |
 ----------- ---------------------------------
| on xeon   |         65.69 / -1 %            |
 ---------------------------------------------
| on athlon |         65.35 / -0.2 %          |
 ---------------------------------------------

  Observation : no noticeable overhead


2 - with net_ns compiled in
---------------------------


    2.1 - without container
    -----------------------

 ----------- -----------------------------------------------------------
| Netperf   | CPU usage (%) / overhead | Throughput (Mbits/s) / changed |
 ----------- -----------------------------------------------------------
| on xeon   |      6.02 / +0.5 %       |        941.34  / 0 %           |
 -----------------------------------------------------------------------
| on athlon |      27.93 / -0.8 %      |        833.53 /  -1.3 %        |
 -----------------------------------------------------------------------

 ----------- ---------------------------------
| Tbench    | Throughput (MBytes/s) / changed |
 ----------- ---------------------------------
| on xeon   |         66.00 / -0.5 %          |
 ---------------------------------------------
| on athlon |         64.94 / -0.9 %          |
 ---------------------------------------------

  Observation : no noticeable overhead


    2.2 - inside the container with real device
    -------------------------------------------

 ----------- -----------------------------------------------------------
| Netperf   | CPU usage (%) / overhead | Throughput (Mbits/s) / changed |
 ----------- -----------------------------------------------------------
| on xeon   |      5.60 / -6.5 %       |        941.42  / 0 %           |
 -----------------------------------------------------------------------
| on athlon |      27.73 / -1.5 %      |        835.11 /  +1.5 %        |
 -----------------------------------------------------------------------

 ----------- ---------------------------------
| Tbench    | Throughput (MBytes/s) / changed |
 ----------- ---------------------------------
| on xeon   |         74.36 / +12 %           |
 ---------------------------------------------
| on athlon |         70.87 / +8.2 %          |
 ---------------------------------------------

  Observation : no noticeable overhead. The network interface is only
  used by the container, so I guess it does not interact with another
  network traffic and that explains the performances are better.


    2.3 - inside the container with etun and routes
    ----