Re: [Xen-users] XEN 4.3.1 network performance issue

[Wei Liu <wei.liu2@xxxxxxxxxx>]

On Tue, Dec 24, 2013 at 05:06:37PM +0200, NiX wrote:
> Hi. I am running a XEN VM in PV mode. This VM has four cores enabled. VM
> network config is as follows:
> 
> vif = ["ip=127.0.0.1,mac=XX:XX:XX:XX:XX:XX,bridge=br0,rate=100Mb/s"]
> 
> Dom0 is dual XEON X5450 with 16GB of RAM.
> 
> I can barely zmap at 10mbps ~ 12k packets/second on this VM
> 

My google-fu tells me that zmap sends out gigantic amount of TCP SYN
packets in its default configuration. It is possible the ring size
between frontend and backend is the bottleneck. Data copying from
frontend to backend might also be a problem.

You can probably patch your Dom0 and DomU kernel with multi-page ring
support to see if it makes it better.

Wei.

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