Interrupts in L4Linux

[Norman Feske]

Hi Vasily,

thanks for this nuanced discussion. It helps me lot to understand your
situation. For example, I didn't have the binary-blob problem on my
radar at all.

> I agree that would be worth L4Linux seen only as a sandbox for Linux
> binaries execution. Again, ideologically correct exclude drivers from
> L4Linux. But there are some problems. In addition to the noticed above
> there is another one. Is is a performance. Now we make some
> experiments with L4linux as gateway with two dedicated NIC drivers and
> L4Linux. And we see that the performance degradation is around 85% in
> contrast with Linux. That is too much, and if it turns that the moving
> NIC driver back to L4Linux ( ie if we give acces L4Linux network
> driver to HW) can decrease performance degradation (security
> architecture allows to do it), we will use this approach.

I suspect that the poor networking performance stems from the dde_ipxe
networking driver, not L4Linux. I would definitely recommend to
benchmark the dde_ipxe networking driver individually without L4Linux.
E.g., by adding some code to the driver that transmits a predefined
network packet and measure the throughput achieved.

Another test would be to connect two L4Linux instances via nic_bridge
and perform the benchmark between both instances. If the communication
over the virtual network performs well, we can rule out L4Linux and the
'Nic_session' interface from being the problem.

> And oddly enough, the applications for the ARM easier develop from
> scratch and not use L4Linux for binaries execution. While software for
> network equipment, based on x86, increasingly require re-using.
> We have not looked NOVA and Vancouver yet. If we can not solve
> performance problems with L4Linux we will "taste" them.

Please let us know how you like the taste once you try it. ;-)

Norman

-- 
Dr.-Ing. Norman Feske
Genode Labs

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