Re: [Xen-users] bad network perfornance too many frags messages

[Alexis Pellicier <alexis.pellicier@xxxxxxxxxx>]

I've just checked on other server running opensuse12.2 ( 3.4.33 kernel) both on the Dom0 and DomU.

sg-feature is on either on the backend and the frontend and transfer rate is ok on the DomU with no error in the logs.

I was wondering if it could be related to opensuse distro?

2013/4/8 Alexis Pellicier <alexis.pellicier@xxxxxxxxxx>

Ok thank for your help
Here my report on what I did:

-edit sg=0 in xenbus.c
-recompile xenbus_be.ko netbk.ko xennet.ko

-replace these 3 modules in my Dom0 reboot
-replace these 3 modules in my DomU reboot

-xenstore-ls gave feature-sg=0 for backend
-xenstore-ls gave feature-sg=1 for frontend. (I couldnât disable it)

My test still show me really bad transfer rate and those Too may frags kernel error in DomU logs.

Any further clue?

2013/4/8 Wei Liu <wei.liu2@xxxxxxxxxx>

On Mon, Apr 08, 2013 at 01:35:32PM +0100, Alexis Pellicier wrote:
> xenstore-ls /local/domain/14/device/vif/0
>
> show me
> backend = "/local/domain/0/backend/vif/14/0"
> feature-sg = "1"
>
>
> xenstore-ls /local/domain/0/backend/vif/14/0
> feature-sg = "1"
>
> So I guess it means sg is enable on both backend and frontend.
>

SG is always used whenever possible. This has nothing to do with the
bridge.

Unfortunately there is no option to disable it. If you fancy recompiling
backend driver, look at drivers/net/xen-netback/xenbus.c:netback_probe
and change 'sg = 1' to 'sg = 0'.


Wei.

>
> Sorry for the top post I was just "reply to all" in my mailer.
>

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