Re: [Xen-devel] arm: network throughput decreases 5Mbps (Arndale Exynos5250)

[Sengul Thomas <thomas.sengul@xxxxxxxxx>]

>> This typically happens when I generate traffic using iperf (100Mbps)
>> while installing some packages using apt-get in dom0.
>> Whenever this behavior happens, I can not see any distinguishable logs
>> from any places.
>
> How strange. Do you get any packet loss or just slow delivery of the
> packets which are flowing?

Just slowing down packet flows, no packet losses. (If network load is moderate)

>
> This is traffic from the dom0 to the outside world, rather than between
> virtual machines on the same host, right?

Yes indeed.
Actually, even this happens, network throughput between virtual
machines are very fast
(I vaguely remember it was larger than 1Gbps).

> So is the Arndale using a USB Ethernet device?
>

Right.


>
> It would also be useful to examine the physical interrupt to be sure it
> was arriving at the hypervisor. On x86 the 'i' key dumps information
> about the physical interrupts (see
> xen/arch/x86/irq.c:dump_irqs_keyhandler) but AFAIK there is no
> equivalent on ARM, apart from a little bit of hardware state printed by
> the 'q' key. If you wanted to code up a more comprehensive dump of the
> physical GIC state and wire it up to 'i; that would be very useful here
> as well as in the future I imagine.

OK, I also think it can help debug this strange network problem.
Let me try coding up.


Thanks,
Thomas

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