Re: [Xen-devel] large packet support in netfront driver and guest network throughput

[Wei Liu <wei.liu2@xxxxxxxxxx>]

On Thu, Sep 19, 2013 at 04:59:49PM +0000, Anirban Chakraborty wrote:
[...]
> >> 
> >> I was able to see a bit of improvement (from 2.65 to 3.6 Gbps) with the 
> >> following patch (your patch plus the advertisement of NETIF_F_GRO) :
> > 
> > OK, thanks for reporting back.
> > 
> > I'm curious about the packet size after enabling GRO. I can get 5G/s
> > upstream with packet size ~24K on a 10G nic. It's not line rate yet,
> > certainly there is space for improvement.
> 
> I am seeing varying packet sizes with the GRO patch, from 2K to all the way 
> upto 64K.
> I do not think we can get line rate by enabling GRO only. The netback thread 
> that is handling the guest traffic is running on a different CPU (and 
> possibly different node) compared to the guest. If we can schedule netback 
> for a guest to run on the same node as the guest, we should be able to see 
> better numbers. 

You can use vcpu pin to pin Dom0's CPUs and Dom0's CPUs to the same NUMA
node. However domain's memory might still be striped across different
nodes.

> In any case, are you going to submit the patch upstream or should I do it? 

I will do that once net-next is open.

Wei.

> Thanks.
> 
> Anirban
> 
> 

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