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

[James Harper <james.harper@xxxxxxxxxxxxxxxx>]

Someone will growl at you if you top post.

> 
> I did ethtool -K br0 sg off
> 
> and still have lots of  (3 per seconds) "netfront: Too many frags" messages in
> the VM'slogs.
> 
> The problem occurs with the host connect at 1GB. If I connected to a 100Mb
> ports the VM's are ok.
> 

Check xenstore to see if sg is enabled in the device setup.

xenstore-ls /local/domain/<domid>/device/vif/0

or something like that. Also check the backend path (shown in the output of the 
above).

James

> 
> 
> 2013/4/8 James Harper <james.harper@xxxxxxxxxxxxxxxx>
> 
> 
>       > Hi,
>       > With a 3.7.10 kernel from openssue 12.3 my paravirtualized vm got
> really
>       > poor network performances.
>       > and I'have this messages every half of a second in the logs:
>       > kernel netfront: Too many frags
>       >
>       > Any idea about what could be the cause and what test I can do?
>       >
>       > I've read something about MAX_SKB_FAGS and offloading but it is
> not that
>       > clear for me.
>       >
> 
>       Does turning off scatter gather on the bridge help at all?
> 
> 

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