[lxc-devel] [PATCH 1/2] Add lxc.network.mtu configuration

[Ryousei Takano]

Hi Daniel,

On Mon, Mar 23, 2009 at 7:04 AM, Daniel Lezcano <dlezcano at fr.ibm.com> wrote:

[snip]

> I played a bit with the patch and noticed the mtu is only set for one side
> of the veth, the one attached to the bridge, so I wrote a patch on top of
> your patch to set both side and applied both patches in the git tree. Maybe,
> that will increase the throughput performances a little more.
>
Thanks for merging my patch.
I checked lxc-0.6.1 and your commit 75d09f83b82f35a610f4922e06ad897692062fab
(set mtu for netdev).

I found a problem of the MTU size of br0.  In the current code,
device_set_mtu() is
called after bridge_attach(), so the MTU size of br0 is set to the
default MTU size
of veth0 (i.e., 1500 bytes).
This causes performance degradation as I reported.

We need to modify to call device_set_mtu() before bridge_attach().

Best regards,
Ryousei Takano