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

Adding back xen-users@

On Sat, Dec 28, 2013 at 07:34:55PM +0200, NiX wrote:
> I ran 'zmap -p 80 -B 10M -o results.txt --interface=eth0' and took a
> screenshot of top.

Is it not the '-B' option limits total bandwidth? In that case it is
normal to see it can only use up to 10Mb/s?

So the snapshot shows that CPU0 is runing at 78% serving software
interrupt while 10% idle. Looks like that backend spends too much
serving interrupt handler and not actually doing any work.

Could you try the following tree:
Which has the latest stable netback / netfront code.

In that tree:
1. netback NAPI to mitigate intrrupt (backend only)
2. a new feature call split event channel can be used to avoid some
   interrupt overhead. (you would need to use frontend / backend that
   support this feature)

P.S. don't use this tree in production. ;-)


> 0:05 0% (1d11h left); send: 74425 14.9 Kp/s (14.8 Kp/s avg); recv: 2196
> 492 p/s (436 p/s avg); drops: 0 p/s (0 p/s avg); hits: 2.95
> 10mbps ~ 15k packets/second
> The server is dual xeon X5450

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